Power Module

Abstract

The present disclosure describes a power module having a substrate, a first plurality of vertical power devices and a second plurality of vertical power devices, and a first terminal assembly and a second terminal assembly. The substrate has a top surface with a first trace and a second trace. The first plurality of vertical power devices are electrically coupled to the second plurality of vertical power devices to form a portion of a power circuit. The first plurality of vertical power devices are directly electrically and mechanically coupled between the first trace and the bottom of a first elongated rod of the first terminal assembly. The second plurality of vertical power devices are directly electrically and mechanically coupled between the second trace and the bottom of a second elongated rod of the second terminal assembly.

Description

Technical Field

[0001] The present disclosure relates to power modules for high power applications. Background Art

[0002] In high power applications, multiple components of all or part of a circuit are often packaged in an electronic module. These modules, generally referred to as power modules, are housed in a thermoplastic, epoxy, or similar molded housing that encloses the components and a circuit board or substrate on which the components are mounted. The input / output connections of the power module are provided by terminal assemblies that extend out of the housing to facilitate incorporation into and connection to other systems. Such systems may include electric vehicles, power conversion and control, etc. Summary of the invention

[0003] The present disclosure relates to a power module, which includes a substrate, a first plurality of vertical power devices and a second plurality of vertical power devices, and a first terminal assembly and a second terminal assembly. The substrate has a top surface with a first trace and a second trace. The first plurality of vertical power devices and the second plurality of vertical power devices are electrically coupled to form a part of a power circuit. The first terminal assembly has a first slender rod, at least two first terminal contacts, and at least two first terminal legs extending between different points of the first slender rod and the at least two first terminal contacts, respectively. The second terminal assembly has a first slender rod, at least two first terminal contacts, and at least two first terminal legs extending between different points of the first slender rod and the at least two first terminal contacts, respectively. The first plurality of vertical power devices are directly electrically coupled and mechanically coupled between the first trace and the bottom of the first slender rod of the first terminal assembly. The second plurality of vertical power devices are directly thermally coupled, electrically coupled, and mechanically coupled between the second trace and the bottom of the second slender rod of the second terminal assembly.

[0004] The power module may also have a third terminal assembly and a fourth terminal assembly. The third terminal assembly and the fourth terminal assembly may be thermally, electrically, and mechanically coupled to the first trace proximate the opposite side of the substrate.

[0005] In one embodiment, the substrate has four sides, the third terminal assembly is located on the first side, and the fourth terminal assembly is close to the second side opposite to the first side, the first terminal assembly is close to the third side located between the first side and the second side, and the second terminal assembly is close to the fourth side located between the first side and the second side and opposite to the third side.

[0006] In one embodiment, the housing encloses at least a portion of the first terminal assembly and the second terminal assembly. Each of the at least two first terminal legs can extend out of a side portion of the housing and fold so that the at least two first terminal contacts extend above and parallel to the top portion of the housing. Similarly, each of the at least two second terminal legs can extend out of a side portion of the housing and fold so that the at least two second terminal contacts extend above and parallel to the top portion of the housing.

[0007] In one embodiment, the third terminal assembly and the fourth terminal assembly are electrically and mechanically coupled to the first trace near opposite sides of the substrate, wherein the substrate has four sides, the third terminal assembly is located on the first side, and the fourth terminal assembly is near a second side opposite to the first side, the first terminal assembly is near a third side located between the first side and the second side, and the second terminal assembly is near a fourth side located between the first side and the second side and opposite to the third side.

[0008] The third terminal assembly may have a third terminal leg extending out of the side portion of the housing and a third terminal contact extending above and parallel to the top portion of the housing. The fourth terminal assembly may have a fourth terminal leg extending out of the side portion of the housing and a fourth terminal contact extending above and parallel to the top portion of the housing.

[0009] The top and bottom surfaces of the housing may have a plurality of grooves that function as creepage extenders to effectively extend the surface distance between certain conductive elements of the power module.

[0010] In one embodiment, the first bar and the at least two first terminal legs of the first terminal assembly form a U-shape, and the second bar and the at least two second terminal legs of the second terminal assembly form a U-shape.

[0011] In one embodiment, the power module further has a first pin assembly having a first pin bar and at least one first pin leg extending from the first pin bar. The first pin bar can be located near the first bar and between at least two first terminal legs. The second pin assembly can have a second pin bar and at least one second pin leg extending from the second pin bar. The second pin bar can be located near the second bar and between at least two second terminal legs.

[0012] At least one first pin leg may have two first pin legs, and at least one second pin leg may have two second pin legs. In such an embodiment, the power module may also have a third pin assembly and a fourth pin assembly. The third pin assembly may have a third pin bar and at least one third pin leg extending from the third pin bar, wherein the third pin bar is located near the first pin bar and between the two first pin legs. The fourth pin assembly may have a fourth pin bar and at least one fourth pin leg extending from the fourth pin bar, wherein the fourth pin bar is located near the second pin bar and between the two second pin legs.

[0013] In one embodiment, the at least one third pin leg may have two third pin legs, and the at least one fourth pin leg may have two fourth pin legs.

[0014] In one embodiment, the first pin assembly can be electrically connected to a first contact of a first plurality of vertical power devices via a first bonding wire. The second pin assembly can be electrically connected to a second contact of a second plurality of vertical power devices via a second bonding wire. The third pin assembly can be electrically connected to a third contact of the first plurality of vertical power devices via a third bonding wire. The fourth pin assembly can be electrically connected to a fourth contact of the second plurality of vertical power devices via a second bonding wire.

[0015] In one embodiment, the power module has a housing that encloses at least a portion of a first terminal assembly, a second terminal assembly, a first pin assembly, and a second pin assembly. At least one first pin leg and at least one second pin leg extend out of a corresponding side portion of the housing and then flip upward toward the top of the housing at an angle between 75 degrees and 105 degrees. Other embodiments may include angles between 70 degrees and 110 degrees, between 80 degrees and 100 degrees, between 85 degrees and 95 degrees, and between 87 degrees and 93 degrees.

[0016] In one embodiment, the first plurality of vertical power devices and the second plurality of vertical power devices are field effect transistors. In addition, the first pin assembly is electrically coupled to one of the gate contacts or source contacts of the first plurality of vertical power devices; and the second pin assembly is electrically coupled to one of the gate contacts or source contacts of the second plurality of vertical power devices.

[0017] In one embodiment, a third pin assembly is electrically coupled to another of the gate contacts or source contacts of the first plurality of vertical power devices. A fourth pin assembly is electrically coupled to another of the gate contacts or source contacts of the second plurality of vertical power devices. In one embodiment, the first plurality of vertical power devices have at least three first vertical transistors electrically coupled in parallel to each other, and the second plurality of vertical power devices have at least three second vertical transistors electrically coupled in parallel to each other. In this embodiment, the at least three first vertical transistors and the at least three second vertical transistors may be silicon carbide transistors, and the substrate may be silicon carbide. For applications requiring less power handling capability than in a fully populated embodiment, certain power device locations may be reduced.

[0018] In one embodiment, the first plurality of vertical power devices and the second plurality of vertical power devices include power field effect transistors, and the power circuit is a half H-bridge circuit.

[0019] In one embodiment, the first terminal assembly has a plurality of jumpers extending from the first elongated rod to the second trace such that the plurality of jumpers are electrically and mechanically connected to the second trace.

[0020] In one embodiment, the first terminal assembly and the second terminal assembly are components of a common lead frame.

[0021] In one embodiment, the power circuit has a power loop and at least one signal loop. The power loop passes through the first plurality of vertical power devices and the second plurality of vertical power devices. The power loop is independent of the at least one signal loop. The at least one signal loop can provide at least one control signal for the first plurality of vertical power devices or the second plurality of vertical power devices. In one configuration, the power loop does not pass through any bonding wires of the power module.

[0022] In one embodiment, both the first terminal assembly and the second terminal assembly are symmetrical along at least one axis.

[0023] Based on the above, the present disclosure relates to a compact, high voltage, high current, low inductance half-bridge power module designed for next generation silicon carbide (SiC) and other material system power devices and power electronics applications. It utilizes a novel layout that combines a size and cost optimized power substrate with a multifunctional copper layer that interconnects the top pads of the device while also serving as an external terminal.

[0024] In another embodiment, the power module includes a substrate, a first plurality of vertical power devices, a second plurality of vertical power devices, a housing, and various terminal assemblies. The substrate has a top surface with a first trace and a second trace. The first plurality of vertical power devices are electrically coupled to the second plurality of vertical power devices to form a portion of a power circuit. The first terminal assembly includes a first elongated rod, at least two first terminal contacts, and at least two first terminal legs extending between different points of the first elongated rod and the at least two first terminal contacts, respectively. The second terminal assembly includes a second elongated rod, at least two second terminal contacts, and at least two second terminal legs extending between different points of the second elongated rod and the at least two second terminal contacts, respectively.

[0025] The housing includes four sides between the top surface and the bottom surface, wherein the housing encloses at least a portion of the first terminal assembly and the second terminal assembly. The first of the at least two first terminal legs extends out of the first side of the housing and is folded so that the at least two first terminal contacts extend above the bottom surface of the housing and parallel to the bottom surface. Each of the at least two second terminal legs extends out of the third side of the housing and flips downward, wherein the at least two second terminal contacts form an angle between 75 degrees and 105 degrees with the bottom surface of the housing, wherein the third side is located between the first side and the second side of the housing. Other embodiments may include an angle between 70 degrees and 110 degrees, between 80 degrees and 100 degrees, between 85 degrees and 95 degrees, and between 87 degrees and 93 degrees.

[0026] The power module can be configured so that the first plurality of vertical power devices are directly electrically and mechanically coupled between the first trace and the bottom of the first elongated rod of the first terminal assembly. The second plurality of vertical power devices can also be directly electrically and mechanically coupled between the second trace and the bottom of the second elongated rod of the second terminal assembly.

[0027] In one embodiment, a plurality of first protrusions are disposed in the first elongated rod and are biased toward the substrate, and a plurality of second protrusions are disposed in the second elongated rod and are biased toward the substrate. Each of the first plurality of vertical power devices is directly electrically and mechanically coupled between the first trace and the bottom of one of the first plurality of protrusions in the first elongated rod of the first terminal assembly. Each of the second plurality of vertical power devices is directly electrically and mechanically coupled between the second trace and the bottom of one of the second plurality of protrusions in the second elongated rod of the second terminal assembly.

[0028] The power module may also include a third terminal assembly and a fourth terminal assembly that are electrically and mechanically coupled to the second trace near the opposite side of the substrate. The third terminal assembly may include a third terminal leg extending out of the first side portion of the housing and a third terminal contact extending above and parallel to the bottom surface of the housing. The fourth terminal assembly includes a fourth terminal leg extending out of the second side of the housing and a fourth terminal contact extending above and parallel to the bottom surface of the housing.

[0029] The power module may also include a first pin assembly including a first pin bar and at least one first pin leg extending from the first pin bar and extending out of a fourth side of the housing and then flipping downward at an angle between 75 and 105 degrees from the bottom surface of the housing, wherein the fourth side is opposite to the third side of the housing. A second pin assembly includes a second pin bar and at least one second pin leg extending from the second pin bar and extending out of a fourth side of the housing and then flipping downward at an angle between 75 and 105 degrees from the bottom surface of the housing. Other embodiments may include angles between 70 and 110 degrees, between 80 and 100 degrees, between 85 and 95 degrees, and between 87 and 93 degrees.

[0030] The power module may also include a third pin assembly and a fourth pin assembly. The third pin assembly may include a third pin rod and at least one third pin leg, the third pin leg extending from the third pin rod and extending out of the third side of the housing, and then turning downward at an angle between 75 degrees and 105 degrees with the bottom surface of the housing. The fourth pin assembly may include a fourth pin rod and at least one fourth pin leg, the fourth pin leg extending from the fourth pin rod and extending out of the third side of the housing, and then turning downward at an angle between 75 degrees and 105 degrees with the bottom surface of the housing, wherein at least one third pin leg and at least one fourth pin leg are located between at least two second terminal contacts. Other embodiments may include angles between 70 degrees and 110 degrees, between 80 degrees and 100 degrees, between 85 degrees and 95 degrees, and between 87 degrees and 93 degrees.

[0031] In some embodiments, the first terminal assembly may include a fifth pin leg that extends out of the fourth side of the housing and then flips downward at an angle between 75 and 110 degrees to the bottom surface of the housing. Similarly, the second terminal assembly may include a sixth pin leg that extends out of the third side of the housing and then flips downward at an angle between 75 and 110 degrees to the bottom surface of the housing. Other embodiments may include angles between 70 and 110 degrees, between 80 and 100 degrees, between 85 and 95 degrees, and between 87 and 93 degrees.

[0032] The power circuit may include a power loop and at least one signal loop, wherein the power loop passes through the first plurality of vertical power devices and the second plurality of vertical power devices. The power loop may be independent of the at least one signal loop. In addition, the at least one signal loop may provide at least one control signal for the first plurality of vertical power devices or the second plurality of vertical power devices. In some embodiments, the power loop does not pass through any bonding wires of the power module.

[0033] The first plurality of vertical power devices and the second plurality of vertical power devices may include power field effect transistors, wherein the power circuit is a half H-bridge circuit.

[0034] The second terminal assembly may include a plurality of jumpers extending from the first elongated rod to the first trace such that the plurality of jumpers are electrically and mechanically connected to the first trace.

[0035] In another embodiment, the power module is configured as follows. The substrate has a top surface with a first trace and a second trace. The first plurality of vertical power devices and the second plurality of vertical power devices are electrically coupled to form a portion of a power circuit. The first terminal assembly has a first elongated rod, at least two first terminal contacts, and at least two first terminal legs extending between different points of the first elongated rod and the at least two first terminal contacts, respectively, wherein a plurality of first protrusions are disposed in the first elongated rod and are biased toward the substrate. The second terminal assembly has a second elongated rod, at least two second terminal contacts, and at least two second terminal legs extending between different points of the second elongated rod and the at least two second terminal contacts, respectively, wherein a plurality of second protrusions are disposed in the second elongated rod and are biased toward the substrate.

[0036] Each of the first plurality of vertical power devices can be directly electrically and mechanically coupled between the first trace and the bottom of one of the first plurality of protrusions in the first elongated rod of the first terminal assembly. Each of the second plurality of vertical power devices can be directly electrically and mechanically coupled between the second trace and the bottom of one of the second plurality of protrusions in the second elongated rod of the second terminal assembly.

[0037] The hallmarks of these designs are scalability and modularity. The layout can be widened and lengthened to (1) accommodate larger devices or (2) place more devices in parallel. Essentially, the package concept can be scaled up or down to meet power handling requirements without losing any of the performance benefits the package provides. It is also simple to arrange these packages in parallel, increasing the current of the converter and / or forming topologies such as full-bridge (commonly used in DC-DC power conversion) and three-phase (used in motor drives and inverters).

[0038] Scalability and modularity are aspects of the product design so that a wide range of offerings and configuration combinations can be supported by the platform. As described below, the present disclosure can be scaled up or down to best meet the needs of a specific application.

[0039] Those skilled in the art will understand the scope of the present disclosure and realize additional aspects thereof after reading the following detailed description in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several aspects of the disclosure and, together with the description, serve to explain the principles of the disclosure.

[0041] Figure 1A and Figure 1B A schematic diagram of a typical half H-bridge circuit is shown.

[0042] Figure 2 Shows Figure 1A The actual implementation of the half H-bridge circuit in .

[0043] Figure 3 is an isometric view of an external structure of a power module according to a first embodiment of the present disclosure.

[0044] Figure 4 is an isometric view of the internal structure of the first embodiment of the present disclosure.

[0045] Figure 5 It is a top view of the internal structure of the first embodiment of the present disclosure.

[0046] Figure 6 is an exploded view of the first embodiment of the present disclosure.

[0047] Figure 7 is a top view of the internal structure of an alternative embodiment of the present disclosure.

[0048] Figure 8 An exemplary power loop of the first embodiment of the present disclosure is shown.

[0049] Fig. 9A A first embodiment of a terminal connection to a lower layer of a low inductance busbar according to the present disclosure is shown.

[0050] Fig. 9B A first embodiment of a terminal connection to an upper layer of a low inductance busbar according to the present disclosure is shown.

[0051] Fig. 9C A second embodiment of a terminal connection to an upper layer of a low inductance busbar according to the present disclosure is shown.

[0052] Fig. 10AA second embodiment of a terminal connection to a lower layer of a low inductance busbar according to the present disclosure is shown.

[0053] Fig. 10B A third embodiment of a terminal connection to an upper layer of a low inductance busbar according to the present disclosure is shown.

[0054] Fig.11 An exemplary signal loop according to a first embodiment of the present disclosure is shown.

[0055] Fig.12 Direct bonding to a power substrate is shown according to one embodiment of the present disclosure.

[0056] Fig.13 The balanced current paths between devices due to transconductance mismatch are shown.

[0057] Fig.14A and Fig. 14B are front and rear isometric views of an outer housing of a power module according to one embodiment of the present disclosure.

[0058] Fig. 14C and Fig.14D yes Fig.14A and Fig. 14B Top view and cross-sectional view of the outer housing of the power module.

[0059] Fig.15 An outline of a power module housing according to one embodiment of the present disclosure is shown.

[0060] Fig.16A , Fig. 16B , Fig. 16C and Fig.16D Various examples of signal pin assemblies according to the present disclosure are shown.

[0061] Fig.17A and Fig. 17B An example of signal pin trimming according to the present disclosure is shown.

[0062] Fig.18 Lead frame features according to one embodiment of the present disclosure are shown.

[0063] Fig.19A and Fig.19B are isometric and plan views of a lead frame portion according to the present disclosure.

[0064] Fig. 20 One embodiment of a lead frame array according to the present disclosure is shown.

[0065] Fig.21 A major variation of a power module according to the present disclosure is shown.

[0066] Fig.22A and Fig. 22B A fully populated power module and a partially populated power module according to the present disclosure are shown.

[0067] Fig.23 An example of paralleling power modules with stacked busses to form a higher power half-bridge is shown according to one embodiment of the present disclosure.

[0068] Fig.24 A power module arranged in a full-bridge topology is shown according to one embodiment of the present disclosure.

[0069] Fig.25 A power module arranged in a three-phase topology is shown according to one embodiment of the present disclosure.

[0070] Fig.26 The power modules are shown arranged in a three-phase topology with two parallel power modules per leg according to one embodiment of the present disclosure.

[0071] Fig. 27 is a first isometric view of an external structure of a power module according to another embodiment of the present disclosure.

[0072] Fig.28 According to the present disclosure Fig. 27 A second isometric view of the external structure of a power module of an embodiment.

[0073] Fig.29 According to the present disclosure Fig. 27 An isometric view of the internal structure of a power module of an embodiment.

[0074] Fig.30 According to the present disclosure Fig. 27 A plan view of the internal structure of a power module of an embodiment.

[0075] Fig.31 According to the present disclosure Fig. 27 An exploded view of a power module of an embodiment of the present invention.

[0076] Fig.32 According to the present disclosure Fig. 27 A third isometric view of the external structure of a power module of an embodiment of the invention, wherein the housing is removed.

[0077] Fig.33A and Fig.33B are isometric and plan views of a lead frame portion according to the present disclosure.

[0078] Fig.34 One embodiment of a lead frame array according to the present disclosure is shown.

[0079] Fig.35 and Fig.36 are first and second isometric views illustrating a wider variation of a power module according to the present disclosure, wherein the wider implementation supports additional power devices for a power module having higher power handling capabilities.

[0080] Fig.37 and Fig.38 are first and second isometric views illustrating narrower variations of power modules according to the present disclosure, wherein the narrower implementation supports fewer or smaller power devices for power modules having lower power handling capabilities. DETAILED DESCRIPTION

[0081] The embodiments set forth below represent the necessary information to enable those skilled in the art to practice the embodiments, and illustrate the best mode for practicing these embodiments. After reading the following description with reference to the accompanying drawings, those skilled in the art will understand the concepts of the present disclosure, and will recognize the applications of these concepts not specifically mentioned herein. It should be understood that these concepts and applications fall within the scope of the present disclosure and the appended claims.

[0082] It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element without departing from the scope of this disclosure. As used herein, the term "and / or" includes any and all combinations of one or more associated listed items.

[0083] It will be understood that when an element such as a layer, region, or substrate is referred to as being "on" or extending "on" another element, it may be directly on or directly extending to another element, or there may also be an intervening element. In contrast, when an element is referred to as "directly on" another element or extending "directly" to another element, there are no intervening elements. Similarly, it will be understood that when an element such as a layer, region, or substrate is referred to as being "on" another element or extending "on" another element, it may be directly on or directly extending to another element, or there may also be an intervening element. In contrast, when an element is referred to as extending "directly on" another element or "directly on" another element, there are no intervening elements. It will also be understood that when an element is referred to as being "connected" or "coupled" to another element, it may be directly connected or coupled to another element, or there may be an intervening element. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements.

[0084] Relative terms such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical" may be used herein to describe the relationship of one element, layer or region to another element, layer or region as illustrated in the figures. It will be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.

[0085] The terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. As used herein, the singular forms "a", "an" and "the" are also intended to include the plural forms unless the context clearly indicates otherwise. It will also be understood that when used herein, the terms "comprises", "comprising", "includes", and / or "including" specify the presence of stated features, wholes, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, parts and / or groups thereof.

[0086] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those commonly understood by those of ordinary skill in the art to which the present disclosure belongs. It will also be understood that the terms used herein should be interpreted as having a meaning consistent with their meaning in the context of this specification and the relevant field, and will not be interpreted as an idealized or overly formal meaning unless explicitly defined as such herein.

[0087] The present disclosure relates to power modules for use in high power applications. A power module may include one or more power semiconductor devices, such as metal oxide semiconductor field effect transistors (MOSFETs), insulated gate bipolar transistors (IGBTs), diodes, etc., arranged in various circuit topologies. Typical circuit topologies include, but are not limited to, a single switch, a half H-bridge circuit, a full H-bridge circuit, and a three-phase switching circuit, which is often referred to as a six-pack.

[0088] For the following discussion, a half-bridge circuit is used to facilitate understanding of the packaging concepts disclosed herein. The basic half-H-bridge circuit is a common power circuit used to switch different voltages to a load such as a Figure 1A and Figure 1BThe motor shown in ). The key components of the half H-bridge circuit are the high-side transistor Q1 and the low-side transistor Q2 coupled in series between the V+ terminal and the V- terminal. For this example, it is assumed that transistors Q1 and Q2 are power MOSFETs with drain (D), gate (G1, G2), source (S), and source Kelvin (K1, K2) connections. The drain (D) of transistor Q1 is coupled to the V+ terminal, and the source (S) of transistor Q2 is coupled to the V- terminal. The source of transistor Q1 and the drain of transistor Q2 are coupled together and represent the MID terminal, which is basically the output node connected to the load (not shown).

[0089] To increase power handling, multiple power devices may be coupled in parallel with each other. Figure 2 As depicted in , transistor Q1 is represented by three transistors Q1', Q1"' and Q1"' coupled in parallel to each other, and transistor Q2 is represented by three transistors Q2', Q2" and Q2"' coupled in parallel to each other. For the sake of brevity and readability, the parallel transistors Q1', Q1" and Q1"' may be collectively referred to as transistor Q1, and transistors Q2', Q2" and Q2"' may be collectively referred to as transistor Q2. In this example, transistors Q1 and Q2 are vertical N-channel MOSFETs with the drain contact at the bottom of the device and the source, gate and source Kelvin contacts at the top of the device. Figure 2 The half H-bridge circuit in is implemented in the power module implementation described below, but is just one of many types of circuits that would benefit from the concepts provided herein.

[0090] According to a first embodiment, the exemplary power module 10 is Figure 3 , Figure 4 , Figure 5 and Figure 6 Shown in. Figure 3 is an isometric view of a power module 10 having a housing 12 that may be molded. Figure 4 and Figure 5 are isometric and plan views of the power module 10 without the encapsulating molded case 12 . Figure 6 is an exploded view of the power module 10. The following description refers to Figure 3 , Figure 4 , Figure 5 and Figure 6 Each one of them.

[0091] At the core of the power module 10 is a substrate 14 to which power devices 16 are mounted on the top surface. In this embodiment, the power devices 16 are transistors Q1 (i.e., Q1', Q1", Q1"') and Q2 (i.e., Q2', Q2", Q2"'). A first terminal assembly, referred to as a V-terminal assembly 18, is mounted above transistor Q2 (16) located near the A side of the power module 10. The V-terminal assembly 18 is conductive and is directly attached to the source contact located on the top side of transistor Q2 to form a Figure 2 The V-node in .

[0092] Two opposing terminals (referred to as V+ terminal components 22) are mounted near the C side and the D side to a first trace / pad 34 ( Figure 6 ). Transistor Q1 is mounted on substrate 14 so that the drain of transistor Q1 is directly attached to first trace / pad 34. Thus, the drain of transistor Q1 and V+ terminal assembly 22 form Figure 2 The V+ node in .

[0093] Another terminal assembly, referred to as MID terminal assembly 20, is mounted above transistor Q1 (16) located near the B side of power module 10. MID terminal assembly 20 is conductive and is directly attached to the source contact located on the top side of transistor Q1. MID terminal assembly 20 includes an integral jumper 20J that extends to and is directly attached to a second trace / pad 34 to which the drain contact of transistor Q2 is directly attached. Thus, the drain contact of transistor Q2, the source contact of transistor Q1, and MID terminal assembly 20 form a Figure 2 The MID node in .

[0094] The gate contact and source Kelvin contact (G1, K1) of transistor Q1 are electrically coupled to pin assemblies 24, 26 using bonding wires 32, respectively. Similarly, the gate contact and source Kelvin contact (G2, K2) of transistor Q2 are electrically coupled to pin assemblies 28, 30 using bonding wires 32, respectively. Pin assemblies 24, 26, 28, 30 are directly mounted to the top surface of substrate 14 so that they are electrically isolated from each other and from high power V-node, V+ node and MID node. Details related to the design and shape of pin assemblies 24, 26, 28, 30, V-terminal assembly 18, relative MID terminal assembly 20 and V+ terminal assembly 22 are further provided below. It is worth noting that such a design may include additional pins or pin assemblies that provide input nodes or output nodes for the electronic devices provided by the power module 10. These additional pins and pin assemblies can be used for current sensing, temperature sensing, biasing, etc.

[0095] Reference now Figure 61 is an exploded view of the power module 10 in FIG. Starting from the bottom of the figure, the power device 16 including transistors Q1, Q2 is attached to the first trace 34 and the second trace 36 at the mounting location 38 using a device attach material 40. The device attach material 40 can be a solder, adhesive, sintered metal, etc. that provides mechanical structure, high current interconnection and high thermal conductivity.

[0096] The pin assembly 24, 26, 28, 30, the V-terminal assembly 18, the MID terminal assembly 20 and the V+ terminal assembly 22 are formed by a single lead frame 44. The top of the power device 16 and the portion of the substrate 14 are connected to the corresponding bottom portions of the V-terminal assembly 18, the MID terminal assembly 20 and the V+ terminal assembly 22 using the lead frame attachment material 42. The lead frame attachment material can be a solder, adhesive, sintered metal, laser welding, ultrasonic welding, etc. that provides mechanical structure, high current interconnection and high thermal conductivity. The lead frame 44 is usually a metal contact strip for high current external connection and internal interconnection. Any contacts are combined together on a single sheet, usually with multiple products on each sheet, and are processed into arrays before forming and segmenting.

[0097] Bond wires 32 are typically used to connect the control contacts of the power device 16 to the various pin assemblies 24, 26, 28, 30. The bond wires 32 may be large diameter wires capable of supporting ultrasonic or thermosonic bonding of relatively high current electrical interconnects. Alternatively, the pin assemblies 24, 26, 28, 30 may be bonded directly to the power device 16, traces located on the substrate 18, or the like.

[0098] The housing 12 may be formed using a transfer or injection molding process to provide mechanical structure, high voltage isolation. The housing 12 encloses the internal parts of the power module 10. The molding compound used for the housing 12 may be a transfer or compression molded epoxy resin molding compound (EMC) that can provide mechanical structure, high voltage isolation, coefficient of thermal expansion (CTE) matching, and low moisture absorption.

[0099] The V-terminal assembly 18 includes an elongated first rod 18B located between two terminal legs 18L. In the illustrated embodiment, the elongated first rod 18B and the two terminal legs 18L together form a U-shape. Other shapes, such as T-shape, V-shape and C-shape are envisioned. Each of the terminal legs 18L is shaped so that it extends outward from the first rod 18B toward the A side of the power module 10, passes through the side of the housing 12, turns upward toward the top of the housing 12, and then turns inward over a portion of the top of the housing 12 to provide a V-terminal contact 18C. Therefore, the distal portion of each of the terminal legs 18L is bent backward over its middle portion. As described above, the bottom portion of the first rod 18B of the V-terminal assembly 18 is directly attached to the source contact of the transistor Q2 (power device 16). As described in the embodiment further described below, a protrusion E (not shown) may be provided. The V-terminal contact 18C located at the exposed distal end of the terminal leg 18L provides a terminal contact for the first terminal assembly 18.

[0100] Similarly, the MID terminal assembly 20 includes an elongated second rod 20B, which is located between two terminal legs 20L. In the illustrated embodiment, the second rod 20B and the two terminal legs 20L form a U-shape together. Other shapes, such as T-shaped, V-shaped and C-shaped, are envisioned. Each of the terminal legs 20L is shaped so that it extends outward from the end of the second rod 20B toward the B side of the power module, passes through the side of the housing 12, turns upward toward the top of the housing 12, and then turns inward over a portion of the top of the housing 12 to provide a MID terminal contact 20C. Therefore, the distal portion of each of the terminal legs 20L is bent backward over its middle portion. The bottom portion of the second rod 20B of the MID terminal assembly 20 is directly attached to the source contact of the transistor Q1 (power device 16). As described in the embodiment further described below, a projection E (not shown) can be provided. The exposed distal end of the second terminal leg 30 provides a terminal contact for the second terminal assembly 20.

[0101] The MID terminal assembly 20 in this embodiment also includes a plurality of (3) integrally formed jumpers 20J extending from the second rod 20B toward the first rod 18B of the first terminal assembly 18. As described above, the distal end of the jumper 20J is directly attached to the first trace 34 located on the top surface of the substrate 14. The jumper 20J can be replaced with a single rod. In addition, the number of jumpers 20J can vary from one embodiment to another. In some embodiments, each power device 16 will have a jumper 20J that is coupled to the MID terminal assembly 20.

[0102] The two opposite V+ terminal assemblies 22 are shaped similarly to the terminal legs 18L, 20L of the first terminal assembly 18 and the second terminal assembly 20. Other shapes are envisioned. One end of each opposite terminal 22 is directly attached to the second trace 36 located on the top of the substrate 14. Each opposite terminal 22 extends outward from the substrate 14 toward the C side and the D side of the power module 10, passes through the corresponding side of the housing 12, turns upward toward the top of the housing 12, and then turns inward over a portion of the top of the housing 12. Therefore, the distal portion of each of the V+ terminal assemblies 22 is bent back over its middle portion. The exposed distal end of the opposite terminal 22 provides the terminal contact 22C for the V+ terminal assembly 22. As shown, the V-terminal assembly 18 and the MID terminal assembly 20 are located on the opposite sides A and B of the power module 10. The two opposite V+ terminal assemblies 22 are located on the remaining opposite sides C and D of the power module 10. It is worth noting that, depending on the application, the V-terminal contact 18C, the V+ terminal contact 22C, and the MID terminal contact 20C can be coplanar or non-planar. The V-terminal contact 18C, the V+ terminal contact 22C, and the MID terminal contact 20C can also be formed in different configurations, some of which have two bends to form a C-shape, while some may have only one bend to form an L-shape, etc. Non-planar configurations that place contacts on two, three, or more different planes can provide additional options for connecting these contacts to external busbars.

[0103] The nested signal pin assembly 24, 26 and 28, 30 group is arranged between the terminal leg 18L of the V-terminal assembly 18 and the terminal leg 20L of the MID terminal assembly 20. The pin assembly 24, 26, 28, 30 in the illustrated embodiment is U-shaped and includes a pin bar 24B, 26B, 28B, 30B and a pair of pin legs 24L, 26L, 28L, 30L extending from each pin bar 24B, 26B, 28B, 30B. Other embodiments may use L-shape and T-shape for the signal pin bar 24B, 26B, 28B, 30B. The pin legs 24L, 26L, 28L, 30L extend outward through the corresponding sides of the housing 12 and turn vertically upward. The bonding wire 32 electrically connects the power device 16 to the pin bars 24B, 26B, 28B, 30B of the pin assembly 24, 26, 28, 30.

[0104] Generally, there are two types of electrical circuits in a power module: a power circuit and a signal circuit. The power circuit is a high voltage, high current path through transistors Q1 and Q2, which is used to deliver power to a load via the drain (or collector) and source (or emitter) of transistors Q1 and Q2, wherein the load is typically connected to the MID terminal assembly 20. The signal circuit is a low voltage, low current path through the gate G1, G2 (or base) and source S (or emitter) of transistors Q1 and Q2. The gate-source (or base-emitter) signal path actuates transistors Q1 and Q2 to effectively turn on or off transistors Q1 and Q2. As described in detail below, the signal circuit may also require Kelvin connections K1 and K2 to the sources of transistors Q1 and Q2.

[0105] The power loop effectively extends between the V+ terminal assembly 22 and the V- terminal assembly 18. The V+ terminal assembly 22 and the V- terminal assembly 18 are typically connected across a DC power source, such as a battery in parallel with a large capacitor. An exemplary power loop of the power module 10 is shown as Figure 8 shown.

[0106] The opposing V+ terminal assemblies 22 are directly attached to the opposing ends of the second trace 36 located on the substrate 14. Power flows into the power module 10 through the contacts 22C and the legs 22C of the two V+ terminal assemblies 22. Therefore, power flows to the opposing ends of the second trace 36 located on the substrate 14 via the terminal assemblies 22 and flows to the drain contact of the transistor Q1. The drain contact of the transistor Q1 is located on the bottom of the transistor Q1 and is also directly attached to the second trace 36. The transistor Q1 is attached to the second trace 36 between the point where the two V+ terminal assemblies 22 are attached to the second trace 36 and the transistors Q1 are equally spaced from each other and the attachment point of the two V+ terminal assemblies 22.

[0107] Then, power flows upward from the drain of transistor Q1 to the source of transistor Q1 through transistor Q1. The source of transistor Q1 is attached to the bottom side of the second rod 20B of the MID terminal assembly 20. The MID terminal jumper 20J of the MID terminal assembly 20 connects the second rod 20B of the MID terminal assembly 20 to the first trace 34 located on the substrate 14. The drain of transistor Q2 is directly attached to the first trace 34 and is equally spaced from each other. Power flows upward from the drain of transistor Q2 through transistor Q2 to the source of transistor Q2. The source of transistor Q2 is directly connected to the bottom side of the first rod 18B of the V-terminal assembly 18. Therefore, power flows along the first rod 18B via the opposite leg 18L to the contact 18C of the V-terminal assembly 18.

[0108] By using a symmetrical V+ terminal assembly 22 and a symmetrical V-terminal assembly 18, current sharing between devices is balanced, smaller external contacts can be used, which facilitates lead frame panelization and greatly reduces inductance by shortening the total current path of the power loop. As further described below, the contacts 18C, 20C, and 22C of the V-terminal assembly 18, the MID terminal assembly 20, and the V+ terminal assembly 22 can be electrically connected to external interconnections using laser welding, solder, ultrasonic welding, mechanical bonding (clamps, springs, etc.), conductive adhesives, or any other conductive bonding.

[0109] Current must flow through a closed circuit. Therefore, the stray inductance of the package itself is not the only contributor to the full loop inductance. The inductance of the full loop should be considered, including any capacitance of the power supply and capacitors provided across the power supply, external buses and wiring, and the power module 10 itself. Therefore, not only should the internal layout of the power module 10 be low inductance, but the location of the V- terminal assembly 18, MID terminal assembly 20, and V+ terminal assembly 22 should also allow for a low inductance stacked bus or similar interconnect method to connect the power module 10 to the DC power supply.

[0110] There are many effective ways to connect terminals to a high-performance bus. Fig. 9A and Fig. 9B A method of using stacked busbars is depicted: V- busbar 48, MID busbar 50 and V+ busbar 52 to connect to V- terminal assembly 18, MID terminal assembly 20 and V+ terminal assembly 22 respectively. Therefore, the metal plane for the bus extends over the top of the power module 10. For clarity, only the metal components of V- busbar 48, MID busbar 50 and V+ busbar 52 are shown, and the stacked film itself is not shown. The configuration shown provides a high density and low inductance solution, in which adjacent power modules 10 can be closely positioned near each other, such as for paralleling or forming a multi-module topology.

[0111] Specific reference Fig. 9A , V-busbar 48 has a body 48B from which two contacts 48C extend. Contacts 48C are physically and electrically connected to contacts 18C of V-terminal assembly 18. Similarly, MID busbar 50 has a body 50B from which two contacts 50C extend. Contacts 50C are physically and electrically connected to contacts 20C of MID terminal assembly 20. Go to Fig. 9B , V+ busbar 52 has a body 52B from which a single wide contact 52C extends. Contact 52C is physically and electrically connected to contact 22C of the opposing V+ terminal assembly 22. An opening in V+ busbar 52 provides access to contact 48C of V- busbar 48, as well as obtaining a gate G2 signal and a source Kelvin K2 signal through pin assemblies 28, 30. Fig. 9B A bend in the V+ busbar 48 is shown, which may be avoided in some cases by lifting the V+ terminal assembly 22 upward so that it is not coplanar with the V- terminal assembly 18 .

[0112] Fig. 9C An alternative configuration of the V+ busbar 52 is provided. The V+ busbar 52 has an extension 52E extending from a body 52B. The body has two opposing legs 52F that pull down from the extension 52E to the contact 22 of the V+ terminal assembly 22. Fig. 9C The configuration in will sacrifice slightly more inductance (i.e., increased inductance due to the smaller stack-up area) in exchange for a relatively Fig. 9B More strain relief and less stiffness in the configuration.

[0113] Another bus method is Fig. 10A and Fig. 10B Here, the bus extends more along the side of the power module 10 or around the perimeter of the power module. This may be useful in situations where more access to the contact area or power module 10 in general is needed. For example, if a soldering or welding tool needs to directly contact the metal surfaces of the various contacts.

[0114] Specific reference Fig. 10A , the V-busbar 48' has a body 48B' from which two contacts 48C' extend. The V-busbar 48' is offset outside the perimeter of the power module 10, wherein the two contacts 48C' are wrapped around opposite sides of the power module 10 before extending inwardly and downwardly to contact the contacts 18C of the V-terminal assembly 18. Similarly, the MID busbar 50' has a body 50B' from which two contacts 50C' extend. The MID busbar 50' is offset outside the perimeter of the power module 10, wherein the two contacts 50C' are wrapped around opposite sides of the power module 10 before extending inwardly and downwardly to contact the contacts 20C of the MID terminal assembly 20.

[0115] Go to Fig. 10B , the V+ busbar 52' ​​is offset outside the perimeter of the power module 10 and is located above the V- busbar 48'. The V+ busbar 52' ​​has two contacts 52C' that wrap around opposite sides of the power module 10 before extending inwardly and downwardly to contact corresponding contacts 22C of the V+ terminal assembly 22. More busing methods and module variations are envisioned, depending on the specific system configuration. Ultimately, the ultimate goal is to provide a universal and efficient terminal arrangement to allow for a variety of end-user solutions.

[0116] The signal return paths or gate and source connections for each transistor (Q1, Q2) location also benefit from low impedance to minimize the voltage stress on the gates of transistors Q1, Q2 during switching. While gate stress can be buffered or reduced by adding resistors, this is usually at the expense of higher packaging complexity, higher cost, and slower switching speeds. Most importantly, for optimal switching performance, the power return paths and signal return paths should be completely independent of each other to enable lower switching losses through faster, well-controlled dynamics.

[0117] The drain-source (or collector-emitter) and gate-source (or gate-emitter) loops share the same connection at the source (or emitter) of the device. If the power path is coupled into the signal path, additional dynamics are introduced through positive or negative feedback. Typically, negative feedback introduces additional losses when the power path coupling opposes the control signal (i.e., when the control signal tries to turn the device on, the power path coupling tries to turn the device off). Positive feedback often leads to instability because the power path coupling amplifies the control signal until the device is destroyed. Ultimately, the coupling of the power path and the signal path leads to reduced switching quality, slower switching speeds, increased losses, and possible destruction.

[0118] Thus, the independent loops improve the switching quality. In the embodiment shown, the power connection has a separate path from the signal source (called source Kelvin) so that they do not overlap or interfere with each other. The closer the individual connections of the transistors are, the better the switching performance.

[0119] Fig.11 The internal signal loop of the illustrated embodiment is shown. The signal loop of transistor Q1 flows onto and through the G1 pin assembly 24, and then through the bonding wire 32 to the gate contact of transistor Q1, where the signal is provided to transistor Q1. The signal loop flows from transistor Q1 via the source contact of transistor Q1. From the source contact, the signal loop flows directly to and through the K1 pin assembly 26 through another bonding wire 32.

[0120] Similarly, the signal loop of transistor Q2 flows to the G2 pin assembly 28 and passes through the G2 pin assembly, and then passes through the bonding wire 32 to the gate contact of transistor Q2, where the signal is provided to transistor Q2. The signal loop flows from transistor Q2 via the source contact of transistor Q2. The signal loop flows directly from the source contact to and through the K2 pin assembly 30 through another bonding wire 32. As shown in the figure, this is a true source Kelvin implementation, in which the power loop and the signal loop are completely independent.

[0121] Fig.11 The signal loop in is only one implementation method. Fig.12As shown, other embodiments may include additional signal traces 54 located on top of the substrate 14. In such an embodiment, a set of bonding wires 32 first connects the gate and source contacts of the transistor to the additional signal traces 54, and a second set of bonding wires 32 connects these additional signal traces 54 to the appropriate pin components 24-30 (G1, G2, K1, K2). While the latter configuration does allow for a simpler signal pin implementation, it requires significantly larger substrate area, which may result in increased cost. Ultimately, the layout is flexible to be compatible with both, and each embodiment can be enhanced or optimized for different applications or specifications.

[0122] Another problem arises in the transconductance mismatch between paralleled devices. Transconductance is effectively the current gain of the device and corresponds to the relationship between the output current to the input voltage. During switching, the input voltage rises and causes an associated rise in the output current. If there are transconductance differences between paralleled devices (which is common in SiC power devices), the devices will each have slightly different turn-on characteristics. With different currents flowing through the devices, each device is supplied with slightly different voltages. These voltage mismatches will result in a 'balancing current' that flows between the devices during switching.

[0123] This balancing current will prefer the path of least impedance, which may be through the signal loop rather than the power loop. As with interference issues with coupled power and signal loops, this balancing current may affect switching quality. Introducing such high, uncontrolled currents through the signal loop may also bring reliability issues, as the signal loop is not designed to carry high currents.

[0124] In one embodiment, significantly lower inductance is found by extending a metal tab across the source pad located on the top side of the device. These paths are depicted in Fig.13 In contrast, the effective path length and cross section of the source junction path has a relatively high impedance. In practice, the balancing current will flow through the power contacts and not interfere with the signal.

[0125] Now go to FIG. 14A to FIG. 14D The package is enclosed by a protective plastic or epoxy housing 12 by transfer molding, compression molding, injection molding or similar processes. Several notable features of the housing 12 are FIG. 14A to FIG. 14D are highlighted in the table and discussed below. Fig. 14B As shown, the backside metal of the power substrate 14 is exposed on the underside of the power module 10 to provide a thermal pad 56. The thermal pad 56 serves as a thermal contact surface to remove heat from the power module 10. The thermal pad 56 can be sintered, soldered, epoxied, or similarly attached to a heat sink or cold plate (not shown) to further help remove waste heat from the power module 10.

[0126] Features in the housing may vary based on the manufacturing method. FIG. 14A to FIG. 14D embodied embodiment represents the structural features of transfer molding. Four hold down pin traces 57 are shown, but there may be more or fewer hold down pin traces depending on the overall size of the power module 10. During the transfer molding process, hold down pins (not shown) press directly down on the power substrate to limit the amount of plastic seepage or grazing on the exposed portion of the thermal pad 56. This ensures that the thermal surface is free of debris and can be used to effectively remove heat. There are also ejection marks 58 around the periphery of the housing 12. The ejection marks 58 are small recesses formed by ejection pins (not shown) that are used to remove the power module from the mold (not shown) while the power module 10 is still hot. The specific location and associated geometry of these features will vary depending on the specific product size and implementation.

[0127] Clearance and creepage can be important aspects of high voltage products. Between conductors at different voltage potentials, clearance is the shortest direct path through the air between the conductors. Creepage is the shortest direct path along a surface between conductors. Meeting safety standards is a challenge and is often inconsistent with manufacturing methods (tooling, epoxy flow, etc.) and product size (footprint and power density). For small transfer molded packages, especially low profile and high voltage SiC-based products, it is difficult to achieve the right balance.

[0128] In some embodiments, the clearance distance is sufficient and within the standard. In order to increase the creepage distance, and accordingly increase the maximum allowable voltage, a creepage extender 60 is used. A creepage extender 60 is a groove, corrugation or other surface enhancement that extends the surface distance between conductors at different potentials. As shown, the creepage extender 60 is included as part of the plastic or epoxy housing 14, providing additional functionality without increasing cost. Fig. 14C and Fig.14D One implementation of these features is shown on the housing 12 of the power module 10. Other patterns on the top and back sides are possible, depending on the specific design implementation.

[0129] To minimize the length of the power loop, some or all edge power contacts (such as edge power contacts of V-terminal assembly 18 and MID terminal assembly 20) may be inserted from the edge of housing 12 compared to signal contacts (such as pin assemblies 24, 26, 28, 30). Fig.15 The signal contacts provided by the pin assemblies 24, 26, 28, 30 require more space to better accommodate the bonding wires 32 from the device; therefore, their housing portions extend from the edge of the overall housing 12. This contour feature allows for inductance optimization of each of the independent power and signal loops.

[0130] Pin assemblies 24, 26, 28, 30 extend along horizontal strips to accommodate parallel devices. Externally, there are a variety of ways to form pins for contacts that will attach to printed circuit board gate drivers, wires, or the like. Some variations are depicted in FIG. 16A to FIG. 16D For the sake of brevity and clarity, only pin assemblies 28, 30 will be discussed, but the same concepts will apply to pin assemblies 24, 26.

[0131] Fig.16A A first method is shown in Figure 1, wherein the pin assemblies 28, 30 are U-shaped and concentric, as described above. In these embodiments, the legs of the pins extend out of the respective side portions of the housing and then flip upward toward the top of the housing at an angle between 75 and 105 degrees. Other embodiments may include angles between 70 and 110 degrees, between 80 and 100 degrees, between 85 and 95 degrees, and between 87 and 93 degrees.

[0132] The first approach takes advantage of product symmetry. Depending on the position of the pin assemblies 28, 30 away from the housing 12, the holes 30H in the pin stems 30B of the outer pin assembly 30 provide strain relief. Fig. 16B The second method provided in does not include a hole for strain relief. Instead, strain relief is inherent in the pin stem 30B by being U-shaped and allowing a portion of the housing 12 to reside in the U-shaped bend of the pin assembly 28, 30. In other methods, three pins may be used, such as Fig. 16C and Fig.16D In these methods, the outer pin assembly 28 maintains a U-shape with two legs 28L. However, the inner pin assembly 30 located in the center has only a single leg 30L. The rod 30B of the pin assembly 30 can take virtually any shape, such as Fig. 16C Angle or triangle or Fig.16D The T shape in the middle.

[0133] Depending on the specific needs of the end system and the format of its gate driver, further pinout variations may be considered. The illustrated implementation was developed with modularity and flexibility in mind, enabling many potential product variations.

[0134] Other pin modifications include trimming some of the legs from the pin components 24, 26, 28, 30, such as Fig.17A and Fig. 17B For example, removing one leg from the pin assembly 24, 26, 28, 30 allows the gate and / or source Kelvin drivers located on the PCB to use only two of the contacts (as opposed to four in the previous embodiment). An asymmetric approach may be advantageous in maximizing the amount of metal area used by the external bus. Fig.17A In FIG. 1 , the inner pin components 26 and 30 have two legs 26L and 30L, respectively. One leg of the outer pin components 24 and 28 is trimmed so that each of the pin components 24 and 28 has only one leg 24L and 28L. Fig. 17B In the embodiment, the inner pin components 26, 30 and one leg of the outer pin components 24, 28 are trimmed so that only one leg 24L, 26L, 28L, 30L remains for each of the pin components 24, 26, 28, 30.

[0135] As described above, the terminal and pin assemblies 18-30 are formed from the lead frame 44 and combine functions to provide high current internal interconnects, bonding wire locations, and external terminal contact surfaces. Portions or parts of the lead frame 44 are attached to the top side source pads of the transistors Q1, Q2 and to the substrate 14. The lead frame 44 can be attached to various components in a number of ways, including welding, sintering, conductive epoxy, laser welding, ultrasonic welding, etc. Surface enhancement features (such as holes, slits, chamfered edges, etc.) are called 'solder or epoxy snaps' and can be used to enhance the strength of the joint, such as Fig.18 shown.

[0136] The strip on the lead frame 44 that is directly attached to the top side source pad can have some distinguishing features. It may have a variety of solder snap implementations depending on the specific layout of the device being packaged. It may also include corrugations (not shown) between devices for thermal expansion stress relief and enhanced mold flow. Various bends in the lead frame 44 can be used as other means of stress relief.

[0137] On the outside of the power module 10, the terminal and pin assemblies 18-30 will be attached to busbars, wires, printed circuit boards, etc. Vibrations in the system may pull on the terminal and pin assemblies 18-30. It is desirable not to have these external forces push or pull on the power devices or bond wires. To this end, holes and / or other retention features are placed in the lead frame 44, where necessary, so that when the lead frame is pulled, the mold compound filling these holes bears the strain, rather than the sensitive internal components.

[0138] The holes 62 and / or other retention features in the lead frame 44 are placed to match the locations of the hold-down pins used in the transfer molding process. Ideally, these pins press directly on the substrate. The holes 62 provide clearance so that the pins can achieve this. After the assembly is molded, it also acts as a strain relief.

[0139] The lead frame 44 may be made from a metal sheet in an etching or stamping process. Fig.19A and Fig.19BAn example of this is provided in . The contacts and internal features are bonded to the outer frame by narrow tabs. To simplify handling in a panel or magazine, most of the metal sheet starts out flat. Only the internal bends are formed. Since the assembly requires multiple heating processes during manufacturing production, thermal expansion slots are added to break up large copper areas. These limit expansion and warping of the assembly.

[0140] After the lead frame 44 has been attached to the power device and substrate, wire bonded and then molded, it is trimmed off the outer frame at the location of the bond tabs. The bends of the outer contacts are typically folded and formed by process steps and selective trimming.

[0141] For automated batch production, these lead frames 44 are usually patterned into arrays. These arrays are processed in multiple machines, usually loaded from a housing box or rack. The holes on the top and bottom edges are used for fixing, positioning, keying and handling. Fig. 20 An exemplary lead frame array 64 having four lead frames 44 is shown in FIG. The specific features of the lead frames 44 and lead frame array 64 will vary depending on product configuration, product size variations, and manufacturing equipment type.

[0142] A potential benefit of the illustrated embodiment is the ability to scale the primary layout up or down to best meet the power handling and budget requirements of a wide range of systems and applications. The power module 10 can accommodate different combinations of device width and length by parametrically stretching it in different counts in the relevant dimensions. Notably, scaling the power module 10 in this manner will not reduce or limit the core benefits of the basic packaging approach. Figure 5 and Fig.21 An example of scalability is provided in , where Figure 5 A power module 10 having three transistors Q1 (16) and three transistors Q2 (16) is shown, and Fig.21 A laterally stretched power module 10 is shown having six transistors Q1 ( 16 ) and six transistors Q2 ( 16 ).

[0143] In certain embodiments, a shared set of materials is desired to minimize the number of unique production tools required to manufacture the components. Therefore, an alternative form of scalability would be to maintain the same substrate and lead frame layout and adjust the number or size of devices in a given footprint. For example, devices may be wider in some cases (higher current) and narrower in other cases (lower cost). Positions may also be reduced to reduce the maximum power handling relative to a fully populated power module 10. Fig.22A and Fig. 22B An example is provided in . Fig.22A and Fig. 22B The power module 10 in both cases is relatively Figure 5 The power module provided in is stretched laterally to have five positions for transistor Q1 (16) and five positions for transistor Q2 (16). Fig.22A The power module 10 in FIG. 1 is fully populated with five transistors Q1 ( 16 ) and five transistors Q2 ( 16 ). Fig. 22B The power module 10 in is populated with three transistors Q1 (16) and three transistors Q2 (16). Therefore, Fig. 22B The two positions in (unfilled position 70) are intentionally left unfilled, and assuming that the same type of component is used in both cases, then Fig.22A This may correspond to a 40% reduction in power handling compared to the power handling in . In some embodiments, only one transistor Q1 (16) and one transistor Q2 (16) are employed.

[0144] The scalability feature allows for in-package optimization. It is also helpful to provide a design that can also be enhanced or optimized externally. The half-bridge legs of the power module 10 can be arranged to form many topological variations. In most cases, each of the corresponding V- terminal assembly 18 and V+ terminal assembly 20 will be connected to the same low inductance bus. The MID terminal assembly 22 or AC output will (1) be connected to a parallel package for higher currents, (2) remain separate for individual bridge legs, or (3) have some combination of the two.

[0145] Fig.23 An example of a parallel configuration with a stacked bus is shown, wherein the V-terminal assembly, V+ terminal assembly, and MID terminal assembly of three power modules 10A, 10B, and 10C are connected in parallel to an elongated V- bus (not shown), an elongated V+ bus 72, and an elongated MID bus 74, respectively. The number of parallel power modules 10X can be increased or decreased to appropriately or optimally match the power requirements of the system. This feature allows the same core product to be used in many systems at all power levels in a cost-effective manner.

[0146] Fig.24 An example of connecting two half H-bridge power modules 10A and 10B using an appropriate bus to form a single full H-bridge circuit is shown. As shown, the V-terminal assembly (not shown) and the V+ terminal assembly 22 of the two power modules 10A and 10B are connected in parallel to an elongated V- busbar (not shown) and an elongated V+ busbar 72, respectively. A first MID busbar 74A is provided for the MID terminal assembly 20 of the power module 10A, and a second MID busbar 74B is provided for the MID terminal assembly 20 of the power module 10B.

[0147] Fig.25A three-phase topology is shown, which has three bridge legs and uses a stacked bus. Three power modules 10A, 10B and 10C are provided. The V-terminal assembly (not shown) and the V+ terminal assembly 22 of the power modules 10A, 10B and 10C are connected in parallel to an elongated V-bus (not shown) and an elongated V+ bus 72, respectively. A first MID bus 74A is provided for the MID terminal assembly 20 of the power module 10A, a second MID bus 74B is provided for the MID terminal assembly 20 of the power module 10B, and a third MID bus 74C is provided for the MID terminal assembly 20 of the power module 10C.

[0148] Can be combined Fig.23 and Fig.24 The concepts provided in. Fig.26 An arrangement is shown that employs stacked busses to provide three bridge legs, each with two parallel-connected power modules 10. Specifically, using three MID bus bars 74A, 74B, and 74C, for the first leg, power modules 10A and 10B are connected in parallel, for the second leg, power modules 10C and 10D are connected in parallel, and for the third leg, power modules 10E and 10F are connected in parallel.

[0149] Figures 27 to 32 Another exemplary power module 100 is shown in FIG. 1 , which incorporates some of the above-described concepts. Fig. 27 is an isometric view of the top of the power module 100 with the housing 112 . Fig.28 is an isometric view of the bottom of the power module 100 . Fig.29 and Fig.30 are isometric and plan views of the bottom of the power module 100 without the molded case 112 . Fig.31 1 is an exploded view of the power module 100. The following descriptions collectively refer to Figures 27 to 31 Each one of them.

[0150] At the heart of the power module 100 is a substrate 114 with power devices 116 mounted to the top surface of the substrate. In this embodiment, the power devices 116 are transistors Q1 (i.e., Q1', Q1", Q1"') and Q2 (i.e., Q2', Q2", Q2"'). The V-terminal assembly 118 in this embodiment is still mounted above the transistor Q2 (116) located near the A side of the power module 100. The V-terminal assembly 118 is conductive and is directly attached to the source contact located on the top side of the transistor Q2 to form a Figure 2 In this embodiment, four Q1 transistors and four Q2 transistors are shown; however, those skilled in the art will recognize that the number, size, and capabilities of transistors Q1 and Q2 will and can vary from application to application based on the performance and power requirements of power module 100.

[0151] Two opposing V+ terminal assemblies 122 are mounted to first traces / pads 134 ( Fig.31 ). Transistor Q1 is mounted on substrate 114 such that the drain of transistor Q1 is directly attached to first trace / pad 134. Thus, the drain of transistor Q1 and V+ terminal assembly 122 form Figure 2 The V+ node in .

[0152] The MID terminal assembly 120 is mounted above the transistor Q1 (116) located near the B side of the power module 100. The MID terminal assembly 120 is conductive and is directly attached to the source contact located on the top side of the transistor Q1. The MID terminal assembly 120 includes an integral jumper 120J that extends to and is directly attached to the second trace / pad 136 to which the drain contact of the transistor Q2 is directly attached. Thus, the drain contact of the transistor Q2, the source contact of the transistor Q1, and the MID terminal assembly 20 form a Figure 2 The MID node in .

[0153] The gate contact and source Kelvin contact (G1, K1) of transistor Q1 are electrically coupled to pin assemblies 124, 126, respectively, using bonding wires 132. Similarly, the gate contact and source Kelvin contact (G2, K2) of transistor Q2 are electrically coupled to pin assemblies 128, 130, respectively, using bonding wires 132. Pin assemblies 124, 126, 128, 130 are mounted directly to the top surface of substrate 114 so that they are electrically isolated from each other and from the high power V-node, V+ node and MID node. Details related to the design and shape of pin assemblies 124, 126, 128, 130, V-terminal assembly 118, relative MID terminal assembly 120 and V+ terminal assembly 122 are further provided below. Notably, such a design may include additional pins or pin assemblies that provide input nodes or output nodes for the electronic devices provided by power module 100. These additional pins and pin components can be used for current sensing, temperature sensing, biasing, etc.

[0154] Reference now Fig.31 1 is an exploded view of the power module 100 in FIG. Starting from the bottom of the figure, the power device 116 including transistors Q1, Q2 is attached to the first trace 134 and the second trace 136 at the mounting location 138 using a device attach material 140. The device attach material 140 can be a solder, adhesive, sintered metal, etc. that provides mechanical structure, high current interconnection and high thermal conductivity.

[0155] The pin assemblies 118', 120', 124, 126, 128, 130, the V-terminal assembly 118, the MID terminal assembly 120, and the V+ terminal assembly 122 are formed from a single lead frame 144. In this embodiment, the pin assembly 118' is an extension of the V-terminal assembly 118, and the pin assembly 120' is an extension of the MID terminal assembly 120. More details regarding the shape and use of the pin assemblies 118', 120', 124, 126, 128, and 130 will be further provided below.

[0156] The top of the power device 116 and the portion of the substrate 114 connected to the corresponding bottom portion of the V-terminal assembly 118, the MID terminal assembly 120 and the V+ terminal assembly 122 are connected using a lead frame attachment material 142. As described above, the lead frame attachment material 142 can be a solder, adhesive, sintered metal, laser welding, ultrasonic welding, etc. that provides mechanical structure, high current interconnection and high thermal conductivity. The lead frame 144 is usually a metal contact strip for high current external connection and internal interconnection. Any contacts are combined together on a single sheet, usually with multiple products on each sheet, and are processed into arrays before forming and segmenting.

[0157] Bonding wires 132 are typically used to connect the control contacts of the power device 116 to the various pin assemblies 124, 126, 128, 130. The bonding wires 132 can be large diameter wires that can support ultrasonic or thermosonic bonding of relatively high current electrical interconnects. Alternatively, the pin assemblies 124, 126, 128, 130 can be directly bonded to the power device 116, bonded to traces located on the substrate 118, etc. Since the pin assemblies 118' and 120' are integral with and substantially an extension of the corresponding V-terminal assembly 118 and MID terminal assembly 120, these connections do not require bonding wires.

[0158] The housing 112 may be formed using a transfer or injection molding process to provide mechanical structure and high voltage isolation. The housing 112 encloses the internal parts of the power module 100. The molding compound used for the housing 112 may be a transfer or compression molded epoxy molding compound (EMC) that can provide mechanical structure, high voltage isolation, coefficient of thermal expansion (CTE) matching, and low moisture absorption.

[0159] Now go to Figures 27 to 32 (in general), and in particular Fig.29 and Fig.30, the V-terminal assembly 118 includes an elongated first rod 118B located between two terminal legs 118L. A significant difference between the above-mentioned power module 10 and the power module 100 is that the V-terminal assembly 118 is reconfigured so that the V-terminal contact 118C is located on the same side as the V+ terminal contact 122C of the V+ terminal assembly 122. This configuration can provide a slightly more optimized busbar (busbar 118B) that has more overlap with the power device 116 (Q2) and has a smaller in-circuit inductance compared to the above-mentioned power module 10. In the power module 10, the V-terminal contacts 18C are all located on the side opposite to the side of the MID terminal contact 20C of the MID terminal assembly 20.

[0160] Specifically, the corresponding terminal legs 118L are shaped so that they extend outward from the first rod 118B toward the opposite sides C and D of the power module 100, pass through one side of the housing 112, turn upward toward the top of the housing 112, and then turn inward over a portion of the top of the housing 112 to provide corresponding and opposite V-terminal contacts 118C. The distal portion of each of the terminal legs 118L is bent back over its middle portion. The bottom portion of the first rod 118B of the V-terminal assembly 118 is directly attached to the source contact of the transistor Q2 (power device 116). The V-terminal contact 118C located at the exposed distal end of the terminal leg 118L provides a terminal contact for the V-terminal assembly 118.

[0161] The MID terminal assembly 120 includes an elongated second rod 120B, which is located between two terminal legs 120L. In the illustrated embodiment, the second rod 120B and the two terminal legs 120L form a U-shape together. Other shapes, such as T-shaped, V-shaped and C-shaped, are contemplated. Each of the terminal legs 120L is shaped so that it extends outwardly from the end of the second rod 120B toward the B side of the power module, passes through the side of the housing 112, and turns upward toward the top of the housing 112 at an angle between 75 degrees and 105 degrees. Other embodiments can include an angle between 70 degrees and 110 degrees, between 80 degrees and 100 degrees, between 85 degrees and 95 degrees, and between 87 degrees and 93 degrees. The exposed far end of the terminal leg 120L provides the MID terminal assembly 120 with a MID terminal contact 120C.

[0162] A second significant difference between the power module 10 and the power module 100 described above is that the MID terminal contacts 120C do not have the same MID terminals as on the power module 10 (e.g., Figure 3) is folded back over the bottom surface of the housing 112. Like the pin assemblies 120', 124, 126, the MID terminal contact 120C is substantially vertical relative to the plane in which the housing 112 is located. The terminal leg 120L effectively forms an L-shape, wherein the vertical portion of the terminal leg 120L forms the MID terminal contact 120C. The terminal leg 120L extends from the second rod 120B. The bottom portion of the second rod 120B of the MID terminal assembly 120 is directly attached to the source contact of the transistor Q1 (power device 116).

[0163] The MID terminal assembly 120 in this embodiment also includes a plurality of (2) integrally formed jumpers 120J extending from the second rod 120B toward the first rod 118B of the V-terminal assembly 118. As described above, the distal end of the jumper 20J is directly attached to the second trace 136 located on the top surface of the substrate 114. The jumper 120J can be replaced with a single rod. In addition, the number of jumpers 120J can vary from one embodiment to another. For example, three jumpers 120J are provided in the above-mentioned power module 10. In some embodiments, each power device 116 will have a jumper 120J, which is coupled to the MID terminal assembly 120.

[0164] In this embodiment, the terminal legs and contacts 120L, 120C of the MID terminal assembly 120 allow for welding to thicker external busbars using conventional and more readily available side welding operations. Since the MID terminal assembly 120 carries the AC output of the power module 100, thicker busbars may be preferred or required for higher current applications.

[0165] For each of the opposing V+ terminal assemblies 122, one end is directly attached to the first trace 134 located on the top of the substrate 114. Each opposing terminal 122 extends outward from the substrate 114 toward the C side and the D side of the power module 100, passes through the corresponding side of the housing 112, turns upward toward the top of the housing 112, and then turns inward over a portion of the top of the housing 112. Therefore, the distal portion of each of the V+ terminal assemblies 122 is bent back over its middle portion. The exposed distal ends of the opposing terminals 122 provide terminal contacts 122C for the V+ terminal assemblies 122.

[0166] Specific reference Fig.29 and Fig.30, nested groups of signal pin assemblies 118', 120', 124, 126 and 128, 130 are provided on opposite sides of the housing 112. The pin assemblies 126 and 130 are T-shaped and each include a pin stem 126B, 130B and a pin leg 126L, 130L extending from a central portion of the respective pin stem 126, 130. The pin legs 126L, 130L extend laterally outward from the respective pin stem 130B before being turned approximately 90 degrees toward the bottom side of the power module 100.

[0167] The pin assemblies 124 and 128 are generally L-shaped and each include a pin stem 124B, 128B and a pin leg 124L, 128L extending from a distal portion of the respective pin stem 126, 130. The pin legs 126L, 130L extend laterally outward from the respective pin stem 126B, 130B, flip toward the pin legs 126L, 130L of the pin assemblies 126, 130, flip outward approximately 90 degrees, and then flip toward the bottom side of the power module 100 approximately 90 degrees. Other embodiments may include angles between 75 and 105 degrees, between 70 and 110 degrees, between 80 and 100 degrees, between 85 and 95 degrees, and between 87 and 93 degrees.

[0168] The pin assemblies 118' and 120', which are essentially additional pin legs, are integral extensions of the terminal legs 118L and 120L of the respective V-terminal assemblies 118 and MID terminal assemblies 120. The pin assembly 118' extends laterally from the bus bar 118B and / or the terminal leg 118L before turning about 90 degrees toward the bottom side of the power module 100 and finally extending side by side with the pin leg 130L of the pin assembly 130. The pin assembly 120' extends laterally from the bus bar 120B and / or the terminal leg 120L before turning between 75 degrees and 105 degrees toward the bottom side of the power module 100 and finally extending side by side with the pin leg 126L of the pin assembly 126. The end portion of the pin leg 130L of the pin assembly 130 is located between the end portion of the pin assembly 118' and the pin leg 128L of the pin assembly 128. Other embodiments may include angles between 70 and 110 degrees, between 80 and 100 degrees, between 85 and 95 degrees, and between 87 and 93 degrees.

[0169] By extending pin assembly 118' directly from V-terminal assembly 118, pin assembly 118' can be used to sense current and overcurrent events by analyzing the voltage difference between pin assembly 118' and pin assembly 130L, which corresponds to V- and the low-side source Kelvin signal voltage (K2). Similarly, by extending pin assembly 120' directly from MID terminal assembly 120, pin assembly 120' can be used to sense current and overcurrent events by analyzing the voltage difference between pin assembly 120' and pin assembly 126, which corresponds to V- and the high-side source Kelvin signal voltage (K1). Schematically, pin assembly 118' and pin assembly 120' correspond to Figure 1B The S2 signal and S1 signal in. Figure 1A and Figure 1B The S1 and S2 terminals correspond to the pin assemblies 120 ′ and 118 ′ of the current embodiment. Bonding wires 132 electrically connect the power device 116 to the pin bars 124B, 126B, 128B, 130B of the pin assemblies 124 , 126 , 128 , 130 .

[0170] Specific reference Fig. 27 , Fig.28 and Fig.32 The inner workings of the power module 100 are enclosed by a protective plastic or epoxy housing 112 by transfer molding, compression molding, injection molding, or similar processes. Several notable features of the housing 112 are highlighted and discussed below. Fig.28 and Fig.32 As shown, the backside metal of the power substrate 114 is exposed on the underside of the power module 100 to provide a thermal pad 156. The thermal pad 156 serves as a thermal contact surface to remove heat from the power module 100. The thermal pad 156 can be sintered, soldered, epoxied, or similarly attached to a heat sink or cold plate (not shown) to further help remove waste heat from the power module 100.

[0171] The features in the housing 112 may vary based on the manufacturing method. The illustrated embodiment represents the structural characteristics of transfer molding. Fig. 27As shown, there are four hold down pin traces 157, but there may be more or fewer hold down pin traces depending on the overall size of the power module 100. During the transfer molding process, hold down pins (not shown) press directly down on the power substrate to limit the amount of plastic seepage or grazing on the exposed portion of the thermal pad 156. This ensures that the thermal surface is free of debris and can be used to effectively remove heat. There are also ejector marks 158 around the periphery of the housing 112. The ejector marks 158 are small recesses formed by ejector pins (not shown) that are used to remove the power module from the mold (not shown) while the power module 100 is still hot. The specific location and associated geometry of these features will vary depending on the specific product size and implementation.

[0172] Clearance and creepage can be important aspects of high voltage products. Between conductors at different voltage potentials, clearance is the shortest direct path through the air between the conductors. Creepage is the shortest direct path along a surface between conductors. Meeting safety standards is a challenge and is often inconsistent with manufacturing methods (tooling, epoxy flow, etc.) and product size (footprint and power density). For small transfer molded packages, especially low profile and high voltage SiC-based products, it is difficult to achieve the right balance.

[0173] In some embodiments, the clearance distance is sufficient and within the standard. To increase the creepage distance, and accordingly increase the maximum allowable voltage, a creepage extender 60, such as Fig.14A and Fig. 14B A creepage extender for the previously described power module 10 is shown in FIG. A creepage extender 60 is a groove, corrugation, or other surface enhancement that extends the surface distance between conductors at different electrical potentials.

[0174] As described above, there are two types of electrical circuits in the power module: power circuits and signal circuits. The power circuit is a high voltage, high current path through transistors Q1 and Q2, which is used to deliver power to the load via the drain (or collector) and source (or emitter) of transistors Q1 and Q2, where the load is usually connected to the MID terminal assembly 120. The signal circuit is a low voltage, low current path through the gate G1, G2 (or base) and source S (or emitter) of transistors Q1 and Q2. The gate-source (or base-emitter) signal path actuates transistors Q1 and Q2 to effectively turn on or off transistors Q1 and Q2. As described in detail below, the signal circuit may also require the source Kelvin connections K1 and K2 of transistors Q1 and Q2.

[0175] The power loop effectively extends between the V+ terminal assembly 122 and the V- terminal assembly 118. The V+ terminal assembly 122 and the V- terminal assembly 118 are typically connected across a DC power source, such as a battery in parallel with a large capacitor.

[0176] The opposing V+ terminal assemblies 122 are directly attached to the opposing ends of the first trace 134 located on the substrate 114. Power flows into the power module 100 through the contacts 122C and the legs 122C of the two V+ terminal assemblies 122. Thus, power flows to the opposing ends of the first trace 134 located on the substrate 114 via the terminal assemblies 122 and to the drain contact of the transistor Q1. The drain contact of the transistor Q1 is located on the bottom of the transistor Q1 and is also directly attached to the second trace 136. The transistor Q1 is attached to the first trace 134 between the points where the two V+ terminal assemblies 22 are attached to the first trace 134 and the transistors Q1 are equally spaced from each other and the attachment points of the two V+ terminal assemblies 122.

[0177] Then, power flows upward from the drain of transistor Q1 to the source of transistor Q1 through transistor Q1. The source of transistor Q1 is attached to the bottom side of the second rod 120B of the MID terminal assembly 120 at the protrusion E. The MID terminal jumper 120J of the MID terminal assembly 120 connects the second rod 120B of the MID terminal assembly 120 to the second trace 136 located on the substrate 114. The drain of transistor Q2 is directly attached to the second trace 136 and is equally spaced from each other. Power flows upward from the drain of transistor Q2 through transistor Q2 to the source of transistor Q2. The source of transistor Q2 is directly connected to the bottom side of the first rod 118B of the V-terminal assembly 118 at the protrusion E. Therefore, power flows along the first rod 118B to the contact 118C of the V-terminal assembly 118 via the opposite leg 118L.

[0178] Specific reference Fig.29 and Fig.30 , a plurality of protrusions E may be provided in each of the first rod 118B of the V-terminal assembly and the second rod 120B of the MID terminal assembly. The protrusions E are provided above each of the power devices 116 and are used to extend portions of the first rod 118B and the second rod 120B downward toward the top of the power device. Therefore, the remaining unprotruded portions of the first rod 118B and the second rod 120B allow more space between the top of the substrate 114 and the bottom of the first rod 118B and the second rod 120B. The additional space helps manufacture the housing 112 by reducing the amount of pressure required to flow into and fill the area for the molding compound used to form the housing 112.

[0179] The first and second rods 118B and 120B also have recessed areas corresponding to the compression locations on the substrate 114. As described in the previous embodiments, compression pins (not shown) are used in the transfer molding process, wherein the compression pins are generally pressed directly on the substrate 114 to hold some or all components of the power module 100 in place while the housing 112 is formed.

[0180] By using a symmetrical V+ terminal assembly 122 and a symmetrical V-terminal assembly 118, current sharing between devices is balanced and smaller external contacts can be used, which facilitates lead frame panelization and significantly reduces inductance by shortening the total current path of the power loop. As further described below, contacts 118C, 120C, and 122C of the V-terminal assembly 118, the MID terminal assembly 120, and the V+ terminal assembly 122 can be electrically connected to external interconnections using laser welding, solder, ultrasonic welding, mechanical bonding (clamps, springs, etc.), conductive adhesives, or any other conductive bonding.

[0181] Current must flow through a closed circuit. Therefore, the stray inductance of the package itself is not the only contributor to the full loop inductance. The inductance of the full loop should be considered, including any capacitance of the power supply and capacitors provided across the power supply, external buses and wiring, and the power module 100 itself. Therefore, not only should the internal layout of the power module 100 be low inductance, but the location of the V- terminal assembly 118, MID terminal assembly 120, and V+ terminal assembly 122 should also allow for a low inductance stacked bus or similar interconnect method to connect the power module 100 to a DC power source.

[0182] In this embodiment, the signal loop or gate and source connections at each transistor (Q1, Q2) location also benefit from low impedance to minimize the voltage stress on the gates of transistors Q1, Q2 during switching. In addition, the power loop and signal loop are independent of each other to enable lower switching losses through faster, well-controlled dynamics.

[0183] The internal signal loop of this embodiment is similar to Fig.11 . The signal loop of transistor Q1 flows to and through the G1 pin assembly 124, and then through the bonding wire 132 to the gate contact of transistor Q1, where the signal is provided to transistor Q1. The signal loop flows from transistor Q1 via the source contact of transistor Q1. From the source contact, the signal loop flows directly to and through the K1 pin assembly 126 through another bonding wire 132.

[0184] Similarly, the signal loop of transistor Q2 flows to and through the G2 pin assembly 128, and then through the bonding wire 132 to the gate contact of transistor Q2, where the signal is provided to transistor Q2. The signal loop flows from transistor Q2 via the source contact of transistor Q2. The signal loop flows directly from the source contact to and through the K2 pin assembly 130 through another bonding wire 132. As shown in the figure, this is a true source Kelvin implementation, in which the power loop and the signal loop are completely independent.

[0185] To minimize the length of the power loop, some or all edge power contacts (such as the edge power contacts of the V-terminal assembly 118 and the MID terminal assembly 120) may be inserted from the edge of the housing 112 compared to signal contacts (such as the pin assemblies 124, 126, 128, 130). The signal contacts provided by the pin assemblies 124, 126, 128, 130 require more space to better accommodate the bonding wires 132 from the device; therefore, their housing portions extend from the edge of the entire housing 112. This contour feature allows inductance optimization for each of the independent power and signal loops.

[0186] As described above, the terminal and pin assemblies 118-130 are formed from the lead frame 144 and combine functions to provide high current internal interconnects, bonding wire locations, and external terminal contact surfaces. Portions or parts of the lead frame 144 are attached to the top side source pads of the transistors Q1, Q2 and to the substrate 114. The lead frame 144 can be attached to various components in a number of ways, including welding, sintering, conductive epoxy, laser welding, ultrasonic welding, etc. Surface enhancement features (such as holes, slits, chamfered edges, etc.) are called 'solder or epoxy snaps' and can be used to enhance the strength of the joint, such as Fig.18 shown.

[0187] The strip on the lead frame 144 that is directly attached to the top side source pad can have some distinguishing features. It may have a variety of solder snap implementations depending on the specific layout of the device being packaged. It may also include corrugations (not shown) between devices for thermal expansion stress relief and enhanced mold flow. Various bends in the lead frame 144 can be used as other means of stress relief.

[0188] The lead frame 144 may be made from a metal sheet in an etching or stamping process. Fig.33A and Fig.33B An example of this is provided in . The contacts and internal features are bonded to the outer frame by narrow tabs. To simplify handling in a panel or magazine, most of the metal sheet starts out flat. Only the internal bends are formed. Since the assembly requires multiple heating processes during manufacturing production, thermal expansion slots are added to break up large copper areas. These limit expansion and warping of the assembly.

[0189] After the lead frame 144 has been attached to the power device 116 and substrate 114, wire bonded and then molded, it is trimmed off the outer frame at the location of the bond tabs. The bends of the outer contacts are typically folded and formed by a procedural step and selective trimming.

[0190] For automated batch production, these lead frames 144 are typically patterned into arrays. These arrays are processed in multiple machines, typically loaded from a housing box or rack. Holes on the top and bottom edges are used for fixing, positioning, keying, and handling. Fig.34 An exemplary lead frame array 164 having four lead frames 144 is shown in FIG. The specific features of the lead frames 144 and lead frame array 164 will vary depending on product configuration, product size variations, and manufacturing equipment type.

[0191] Fig.35 and Fig.36 are bottom and top isometric views of a wider variation of the power module 100. As described above, the wider variation supports including more power devices 116 for both low-side and high-side transistors, which generally corresponds to a higher power handling capability of the power module 100.

[0192] The power module 10 and the power module 100 described above have many common elements and several unique elements. Each of these elements can be combined in any combination. For example, the protrusion E and the unique pin components 118 ′, 120 ′, 124, 126, 128, 130 can be incorporated into the power module 10.

[0193] Silicon carbide (SiC) power devices offer a high level of performance benefits, including high voltage blocking, low on-resistance, high current, fast switching, low switching losses, high junction temperature, and high thermal conductivity. Ultimately, these characteristics lead to a significant increase in potential power density, that is, the power handled per area or volume.

[0194] However, realizing this potential requires addressing significant challenges at the packaging and system levels. Higher voltages, currents, and switching speeds manifest as significantly higher physical stresses imposed on smaller and more constrained areas. To fully exploit the advantages offered by SiC technology, one or more of the following challenges must be addressed:

[0195] Provide common circuit topology inside the package (internal layout) and outside the package (interconnection);

[0196] Remove waste heat from conduction and switching losses in devices;

[0197] Provide effective electrical isolation between high voltage potentials;

[0198] Provides low power loop inductance for minimal high voltage overshoot during high-speed switching;

[0199] Achieve low signal loop inductance for minimal gate voltage overshoot and ringing;

[0200] Optimize the internal layout for parallel power devices to achieve dynamic and steady-state current sharing;

[0201] Provides low power loop resistance for high current carrying without overheating;

[0202] Provides an external terminal arrangement that is well suited for paralleling modules and features direct placement into circuit topologies; and

[0203] Provide a balanced arrangement of power devices.

[0204] The internal layout or physical arrangement of the package components has a significant impact on each of these factors. As the number of devices inside the package increases, achieving an optimal layout becomes increasingly difficult. Parallelization is a common technique for SiC devices to increase the current capability of the package. As more devices are connected in parallel, the trade-offs between heat spreading, power loop inductance, signal loop inductance, and package size become increasingly difficult to balance. Forming a half-bridge topology brings additional layout challenges as important parameters such as power loop inductance and equal heat transfer between switch locations become more challenging to design.

[0205] In addition to performance, costs should be kept low in order to appeal to a wide range of markets and applications. Some technologies that help reduce costs include:

[0206] Limit the use of a single component by serving multiple functions of the same component;

[0207] Optimize the function and performance of each component through design;

[0208] Limiting the requirement for secondary or finishing operations;

[0209] Use traditional or established manufacturing methods known for high yields;

[0210] Use batch or continuous processing when possible, using panels, strips, arrays, boxes, etc.; and

[0211] Subassembly-based manufacturing approaches to optimize package size and form, such as sizing parts to be manufactured in strips or panels to maximize raw material utilization.

[0212] Ultimately, the combination of internal scalability and external modularity produces a highly adaptable core layout that can be applied to a wide range of system requirements.

[0213] This disclosure involves but is not limited to the following:

[0214] Highly optimized half-bridge package design for next-generation SiC products;

[0215] Scalable layouts, where products can be made by lengthening or widening the package to allow for more SiC area (either through larger devices or more devices in parallel);

[0216] A modular approach to external terminal locations to facilitate paralleling of multiple packages or arranging them in a common circuit topology;

[0217] Ultra-low inductance, balanced power circuit layout;

[0218] Low inductance, balanced signal loop layout;

[0219] True Kelvin implementation for signal loops;

[0220] Left-hand or right-hand signal pin compatibility;

[0221] Low cost by minimizing the number of unique parts used;

[0222] Low cost by minimizing the area of ​​the power substrate;

[0223] Low cost through lead frame array processing;

[0224] High manufacturability using widely adopted lead frame array processing and transfer molding;

[0225] Internally molded voltage creepage extenders on the top and bottom sides of the package; and

[0226] • Direct power attachment of device top side to lead frame.

[0227] The concepts provided above address one, some or all of the above to provide a unique and novel power module 10, 100. Those skilled in the art will recognize improvements and modifications to the present disclosure. All such improvements and modifications are considered to be within the scope of the concepts disclosed herein.

Claims

1. A power module, comprising: a substrate having a top surface with first traces and second traces; a first plurality of vertical power devices and a second plurality of vertical power devices electrically coupled to form a portion of a power circuit; a first terminal assembly comprising a first elongated rod, at least two first terminal contacts, and at least two first terminal legs, the at least two first terminal legs extending between different points of the first elongated rod and the at least two first terminal contacts; a second terminal assembly comprising a second elongated rod, at least two second terminal contacts, and at least two second terminal legs, the at least two second terminal legs extending between different points of the second elongated rod and the at least two second terminal contacts; as well as A housing including four sides between the top surface and the bottom surface, wherein the housing encloses at least a portion of the first terminal assembly and the second terminal assembly such that: A first terminal leg and a second terminal leg of the at least two first terminal legs extend out of a first side and a second side of the housing and are folded so that the at least two first terminal contacts extend above and parallel to the bottom surface of the housing; and Each of the at least two second terminal legs extends out of a third side of the housing and is flipped, wherein the at least two second terminal contacts form an angle between 75 degrees and 105 degrees with the bottom surface of the housing, wherein the third side is located between the first side and the second side of the housing.

2. The power module according to claim 1, wherein: The first plurality of vertical power devices are electrically and mechanically coupled directly between the first trace and a base of the first elongated rod of the first terminal assembly; and The second plurality of vertical power devices are electrically and mechanically coupled directly between the second trace and a base of the second elongated rod of the second terminal assembly.

3. The power module according to claim 2, wherein: a plurality of first protrusions disposed in the first elongated rod and biased toward the base plate; a plurality of second protrusions disposed in the second elongated rod and biased toward the base plate; each of the first plurality of vertical power devices is electrically and mechanically coupled directly between the first trace and a bottom of one of the plurality of first protrusions located in the first elongated rod of the first terminal assembly; and Each of the second plurality of vertical power devices is electrically and mechanically coupled directly between the second trace and a bottom of one of the plurality of second protrusions located in the second elongated rod of the second terminal assembly.

4. The power module according to claim 3, further comprising: a third terminal assembly and a fourth terminal assembly electrically and mechanically coupled to the second trace proximate an opposite side of the substrate, wherein: The third terminal assembly includes a third terminal leg extending out of the first side of the housing and a third terminal contact extending above and parallel to the bottom surface of the housing; and The fourth terminal assembly includes a fourth terminal leg extending out of the second side of the housing and a fourth terminal contact extending above and parallel to the bottom surface of the housing.

5. The power module according to claim 1, further comprising: a third terminal assembly and a fourth terminal assembly electrically and mechanically coupled to the second trace proximate an opposite side of the substrate, wherein: The third terminal assembly includes a third terminal leg extending out of the first side of the housing and a third terminal contact extending above and parallel to the bottom surface of the housing; and The fourth terminal assembly includes a fourth terminal leg extending out of the second side of the housing and a fourth terminal contact extending above and parallel to the bottom surface of the housing.

6. The power module according to claim 1, further comprising: a first pin assembly including a first pin lever and at least one first pin leg, the first pin leg extending from the first pin lever and extending out of a fourth side of the housing and then flipped at an angle between 75 and 105 degrees to the bottom surface of the housing, the fourth side being opposite to the third side of the housing; as well as A second pin assembly includes a second pin rod and at least one second pin leg, wherein the at least one second pin leg extends from the second pin rod and extends out of the fourth side of the shell and then flipped at an angle between 75 degrees and 105 degrees with the bottom surface of the shell.

7. The power module according to claim 6, wherein: The first terminal assembly also includes a third pin leg that extends out of the fourth side of the housing and then flips over at an angle between 75 and 105 degrees to the bottom surface of the housing.

8. The power module according to claim 7, wherein: The first lead bar is located between the second lead bar and the first elongated bar of the first terminal assembly; and The at least one second pin leg is located between the at least one first pin leg and the third pin leg.

9. The power module according to claim 1, further comprising: a first pin assembly including a first pin lever and at least one first pin leg, the first pin leg extending from the first pin lever and out of the third side of the housing and then flipped at an angle between 75 and 105 degrees to the bottom surface of the housing; as well as A second pin assembly includes a second pin rod and at least one second pin leg, wherein the at least one second pin leg extends from the second pin rod and extends out of the third side of the shell and then flipped at an angle between 75 degrees and 105 degrees to the bottom surface of the shell, wherein the at least one first pin leg and the at least one second pin leg are located between the at least two second terminal contacts.

10. The power module according to claim 9, wherein: The second terminal assembly also includes a third pin leg that extends out of the third side of the housing and then flips over at an angle between 75 and 105 degrees to the bottom surface of the housing.

11. The power module according to claim 10, wherein: The first lead bar is located between the second lead bar and the second elongated bar of the second terminal assembly; and The at least one second pin leg is located between the at least one first pin leg and the third pin leg.

12. The power module according to claim 1, further comprising: a first pin assembly including a first pin lever and at least one first pin leg, the at least one first pin leg extending from the first pin lever and extending out of a fourth side of the housing and then flipped at an angle between 75 and 105 degrees to the bottom surface of the housing, the fourth side being opposite to the third side of the housing; a second pin assembly including a second pin lever and at least one second pin leg, the at least one second pin leg extending from the second pin lever and out of the fourth side of the housing and then flipped at an angle between 75 and 105 degrees to the bottom surface of the housing; a third pin assembly including a third pin lever and at least one third pin leg, the at least one third pin leg extending from the third pin lever and out of the third side of the housing and then flipped at an angle between 75 and 105 degrees to the bottom surface of the housing; as well as A fourth pin assembly comprises a fourth pin rod and at least one fourth pin leg, wherein the at least one fourth pin leg extends from the fourth pin rod and extends out of the third side of the shell and then flipped at an angle between 75 degrees and 105 degrees to the bottom surface of the shell, wherein the at least one third pin leg and the at least one fourth pin leg are located between the at least two second terminal contacts.

13. The power module according to claim 12, wherein: The first terminal assembly also includes a fifth pin leg that extends out of the fourth side of the housing and then flips at an angle between 75 degrees and 105 degrees to the bottom surface of the housing; and The second terminal assembly also includes a sixth pin leg that extends out of the third side of the housing and then flips over at an angle between 75 and 105 degrees to the bottom surface of the housing.

14. The power module according to claim 1, wherein: The power circuit includes a power loop and at least one signal loop; and The power loop passes through the first plurality of vertical power devices and the second plurality of vertical power devices.

15. The power module according to claim 14, wherein: The power loop is independent of the at least one signal loop.

16. The power module according to claim 15, wherein: The at least one signal loop provides at least one control signal to the first plurality of vertical power devices or the second plurality of vertical power devices.

17. The power module according to claim 14, wherein: The power loop does not pass through any bonding wires of the power module.

18. The power module according to claim 1, wherein: The first plurality of vertical power devices and the second plurality of vertical power devices include power field effect transistors, and the power circuit is a half H-bridge circuit.

19. The power module according to claim 1, wherein: The second terminal assembly also includes a plurality of jumpers extending from the first elongated rod to the first trace such that the plurality of jumpers are electrically and mechanically connected to the first trace.

20. A power module, comprising: a substrate having a top surface with first traces and second traces; a first plurality of vertical power devices and a second plurality of vertical power devices electrically coupled to form a portion of a power circuit; a first terminal assembly comprising a first elongated rod, at least two first terminal contacts, and at least two first terminal legs, the at least two first terminal legs extending between different points of the first elongated rod and the at least two first terminal contacts, respectively, wherein a plurality of first protrusions are disposed in the first elongated rod and biased toward the substrate; and a second terminal assembly comprising a second elongated rod, at least two second terminal contacts, and at least two second terminal legs, the at least two second terminal legs extending between different points of the second elongated rod and the at least two second terminal contacts, respectively, wherein a plurality of second protrusions are disposed in the second elongated rod and biased toward the substrate; wherein each of the first plurality of vertical power devices is electrically and mechanically coupled directly between the first trace and a bottom of one of the plurality of first protrusions located in the first elongated rod of the first terminal assembly; and Wherein each of the second plurality of vertical power devices is directly electrically and mechanically coupled between the second trace and a bottom of one of the plurality of second protrusions located in the second elongated rod of the second terminal assembly.

21. The power module according to claim 20, wherein: The first plurality of vertical power devices are electrically and mechanically coupled directly between the first trace and a base of the first elongated rod of the first terminal assembly; and The second plurality of vertical power devices are electrically and mechanically coupled directly between the second trace and a base of the second elongated rod of the second terminal assembly.

22. The power module according to claim 21, further comprising: a third terminal assembly and a fourth terminal assembly electrically and mechanically coupled to the second trace proximate an opposite side of the substrate, wherein: The third terminal assembly includes a third terminal leg extending out of a first side of a housing of the power module and a third terminal contact extending above and parallel to a bottom surface of the housing; and The fourth terminal assembly includes a fourth terminal leg extending out of the second side of the housing and a fourth terminal contact extending above and parallel to a top surface of the housing.

23. The power module according to claim 20, further comprising: a first pin assembly including a first pin bar and at least one first pin leg, the at least one first pin leg extending from the first pin bar and extending out of a fourth side of a housing of the power module and then flipped at an angle between 75 and 105 degrees to a bottom surface of the housing, the fourth side being opposite to the third side of the housing; as well as A second pin assembly includes a second pin rod and at least one second pin leg, wherein the at least one second pin leg extends from the second pin rod and extends out of the fourth side of the shell and then flipped at an angle between 75 degrees and 105 degrees with the bottom surface of the shell.

24. The power module according to claim 23, wherein: The first terminal assembly also includes a third pin leg that extends out of the fourth side of the housing and then flips over at an angle between 75 and 105 degrees to the bottom surface of the housing.

25. The power module according to claim 24, wherein: The first lead bar is located between the second lead bar and the first elongated bar of the first terminal assembly; and The at least one second pin leg is located between the at least one first pin leg and the third pin leg.

26. The power module according to claim 20, wherein: The power circuit includes a power loop and at least one signal loop; The power loop passes through the first plurality of vertical power devices and the second plurality of vertical power devices; The power circuit is independent of the at least one signal circuit; and The at least one signal loop provides at least one control signal to the first plurality of vertical power devices or the second plurality of vertical power devices.

27. The power module according to claim 26, wherein: The power loop does not pass through any bonding wires of the power module.

28. The power module according to claim 20, wherein: The substrate, the first plurality of vertical power devices, and the second plurality of vertical power devices include silicon carbide.

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