KR20230079238A - power module - Google Patents

Abstract

The present disclosure describes a power module having a substrate, first and second pluralities of vertical power devices, and first and second terminal assemblies. 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 connected to form part of a power circuit. A first plurality of vertical power devices are electrically and mechanically directly connected between the first trace and the lower end of the first elongated rod of the first terminal assembly. A second plurality of vertical power devices are electrically and mechanically directly connected between the second trace and the lower end of the second elongated rod of the second terminal assembly.

Description

power module

The present disclosure relates to power modules for high power applications.

In high power applications, multiple components for all or part of a circuit are often packaged in electronic modules. Such modules are commonly referred to as power modules housed in a molded housing of thermoplastic, epoxy, or the like that encapsulates the components and the circuit board or substrate on which the components are mounted. Input/output connections to the power module are provided by terminal assemblies that extend out of the housing to facilitate integration and connection to other systems. These systems may include electric vehicles, power conversion and control, and the like.

The present disclosure relates to a power module including a substrate, first and second pluralities of vertical power devices, and first and second terminal assemblies. 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 connected to form part 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 contacts each extending between different points of the first elongated rod and the at least two first terminal contacts. It has terminal legs. The second terminal assembly includes a first elongated rod, at least two first terminal contacts, and at least two first terminal contacts each extending between different points of the first elongated rod and the at least two first terminal contacts. It has terminal legs. A first plurality of vertical power devices are electrically and mechanically directly connected between the first trace and the lower end of the first elongated rod of the first terminal assembly. A second plurality of vertical power devices are thermally, electrically, and mechanically directly connected between the second trace and the lower end of the second elongated rod of the second terminal assembly.

The power module may also have a third terminal assembly and a fourth terminal assembly. Third and fourth terminal assemblies may be thermally, electrically, and mechanically coupled to the first trace proximate opposite sides of the substrate.

In one embodiment, the board has four sides, the third terminal assembly is on the first side, the fourth terminal assembly is proximate to the second side opposite the first side, and the first terminal assembly is on the first side. proximate a third side between the side and the second side, and the second terminal assembly proximate a fourth side opposite the third side and between the first side and the second side.

In one embodiment, the housing encapsulates 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 the side portion of the housing and can be folded so that the at least two first terminal contacts extend over and parallel to the top portion of the housing. Similarly, each of the at least two second terminal legs can extend out of the side portion of the housing and can be folded so that the at least two second terminal contacts extend over and parallel to the top portion of the housing.

In one embodiment, the third terminal assembly and the fourth terminal assembly are electrically and mechanically connected to the first trace proximate to opposite sides of the board, the board having four sides, the third terminal assembly comprising the first trace. side, a fourth terminal assembly proximate a second side opposite the first side, the first terminal assembly proximate a third side between the first and second sides, the second terminal assembly proximate a third side; Between the first side and the second side and proximal to the fourth side opposite the third side.

The third terminal assembly can have a third terminal leg extending out of the side portion of the housing and a third terminal contact extending over and parallel to the top portion of the housing. The fourth terminal assembly can have a fourth terminal leg extending out of the side portion of the housing and a fourth terminal contact extending over and parallel to the top portion of the housing.

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

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

In one embodiment, the power module also has a first pin assembly having a first pin rod and at least one first pin leg extending from the first pin rod. A first pin rod may be positioned adjacent to the first rod and between the at least two first terminal legs. The second pin assembly may have a second pin rod and at least one second pin leg extending from the second pin rod. A second pin bar may be positioned adjacent to the second bar and between the at least two second terminal legs.

The at least one first pin leg may have two first pin legs, and the at least one second pin bridge may have two second pin legs. In this embodiment, the power module may also have third and fourth pin assemblies. The third pin assembly may have a third pin rod and at least one third pin leg extending from the third pin rod, the third pin rod adjacent to the first pin rod and between the two first pin legs. is located in The fourth pin assembly may have a fourth pin rod and at least one fourth pin leg extending from the fourth pin rod, the fourth pin rod adjacent to the second pin rod and between the two second pin legs. is located

In one embodiment, the at least one third pin leg can have two third pin legs and the at least one fourth pin bridge can have two fourth pin legs.

In one embodiment, the first pin assembly may be electrically connected to first contacts of the first plurality of vertical power devices via first bond wires. The second pin assembly can be electrically connected to second contacts of the second plurality of vertical power devices via second bond wires. The third pin assembly may be electrically connected to third contacts of the first plurality of vertical power devices via third bond wires. The fourth pin assembly is electrically connected to the fourth contacts of the second plurality of vertical power devices via second bond wires.

In one embodiment, a power module has a housing encapsulating at least a portion of a first terminal assembly, a second terminal assembly, a first pin assembly, and a second pin assembly. The at least one first pin leg and the at least one second pin leg extend out of respective side portions of the housing and then rotate upward towards 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.

In one embodiment, the first plurality of vertical power devices and the second plurality of vertical power devices are field effect transistors. Additionally, the first pin assembly is electrically connected to one of the gate contacts or source contacts of the first plurality of vertical power devices; The second pin assembly is electrically connected to one of the gate contacts or source contacts of the second plurality of vertical power devices.

In one embodiment, the third pin assembly is electrically connected to another one of the gate contacts or source contacts of the first plurality of vertical power devices. The fourth pin assembly is electrically connected to another one 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 connected in parallel with each other, and the second plurality of vertical power devices have at least three first vertical transistors electrically connected in parallel with each other. It has 2 vertical transistors. 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. Certain power device locations may be less dense for applications that require less power handling capabilities than in fully dense embodiments.

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.

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.

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

In one embodiment, the power circuit has a power loop and at least one signal loop. The power loop continues through the first plurality of vertical power devices and the second plurality of vertical power devices. The power loop is independent of 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 continue through the power module and any bond wires.

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

Based on the foregoing, 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 uses a new layout that incorporates a size and cost optimized power substrate with a multifunctional copper layer interconnecting the top pads of the devices while also serving as external terminals.

In another embodiment, a 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 and the second plurality of vertical power devices are electrically connected to form part of a power circuit. The first terminal assembly includes a first elongate rod, at least two first terminal contacts, and at least two first terminals each extending between different points of the first elongate rod and the at least two first terminal contacts. include the legs The second terminal assembly includes a second elongate rod, at least two second terminal contacts, and at least two second terminals each extending between different points of the second elongate rod and the at least two second terminal contacts. include the legs

The housing includes four sides between the top surface and the bottom surface, and the housing encapsulates at least a portion of the first terminal assembly and the second terminal assembly. A first terminal leg of the at least two first terminal legs extends out of the first side surface of the housing, and the at least two first terminal contacts extend over and are folded parallel to the bottom surface of the housing. Each of the at least two second terminal legs extends out of the third side of the housing and rotates downward, the at least two second terminal contacts form an angle between 75 and 105 degrees with the bottom surface of the housing, and The side is between the first side and the second side 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.

The power module may be configured such that the first plurality of vertical power devices are electrically and mechanically directly connected between the first trace and the lower end of the first elongated rod of the first terminal assembly. The second plurality of vertical power devices are also electrically and mechanically directly connected between the second trace and the lower end of the second elongated rod of the second terminal assembly.

In one embodiment, a plurality of first embossings are provided in a first elongated rod and biased towards the substrate, and a plurality of second embossings are provided in a second elongated rod and biased towards the substrate. Each of the first plurality of vertical power devices is electrically and mechanically connected directly between the first trace and a lower end of one of the first plurality of embossings in the first elongate rod of the first terminal assembly. Each of the second plurality of vertical power devices is electrically and mechanically connected directly between the second trace and a lower end of one of the second plurality of embossings in the second elongate rod of the second terminal assembly.

The power module may further include a third terminal assembly and a fourth terminal assembly electrically and mechanically coupled to the second trace proximate opposite sides of the substrate. The third terminal assembly can include a third terminal leg extending out of the first side portion of the housing and a third terminal contact extending over and parallel to a 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 over and parallel to the bottom surface of the housing.

The power module comprises a first pin assembly comprising a first pin rod and at least one first pin leg, the at least one first pin leg extending from the first pin rod and out of the fourth side of the housing and then extending from the housing. rotated downward at an angle between 75 and 105 degrees with the bottom surface; and the fourth side is opposite the third side of the housing. a second pin assembly comprising a second pin rod and at least one second pin leg, the at least one second pin leg extending from the second pin rod and out of the fourth side of the housing; rotated downward at an angle between 75 and 105 degrees with 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.

The power module may also include third and fourth pin assemblies. The third pin assembly comprises a third pin rod and at least one third pin leg, the at least one third pin leg extending from the third pin rod and out of the third side of the housing and then at 75 degrees with the bottom surface of the housing. rotated downward by an angle between 105 degrees. The fourth pin assembly comprises a fourth pin rod and at least one fourth pin leg, the at least one fourth pin leg extending from the fourth pin rod and out of the third side of the housing and then at 75 degrees with the bottom surface of the housing. and rotated downward at an angle of between 105 degrees, wherein at least a third first pin leg and at least one fourth pin leg are between the at least two second terminal contacts. 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.

In certain embodiments, the first terminal assembly may include a fifth pin leg extending out of the fourth side of the housing and then rotating downward at an angle of between 75 and 110 degrees with the bottom surface of the housing. Similarly, the second terminal assembly may include a sixth pin leg extending out of the third side of the housing and then rotating downward at an angle between 75 and 110 degrees with 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.

The power circuit can include a power loop and at least one signal loop, the power loop continuing through a first plurality of vertical power devices and a second plurality of vertical power devices. The power loop may be independent of at least one signal loop. Additionally, 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 certain embodiments, the power loop does not continue through any of the bond wires of the power module.

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

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.

In another embodiment, a 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 connected to form part 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 contacts each extending between different points of the first elongated rod and the at least two first terminal contacts. With terminal legs, a plurality of first embossments are provided in the first elongate rod and biased toward the substrate. The second terminal assembly includes a second elongate rod, at least two second terminal contacts, and at least two second terminals each extending between different points of the second elongate rod and the at least two second terminal contacts. With legs, a plurality of second embossments are provided in the second elongate bar and biased towards the substrate.

Each of the first plurality of vertical power devices may be electrically and mechanically directly connected between the first trace and a bottom of one of the first plurality of embossings in the first elongate rod of the first terminal assembly. Each of the second plurality of vertical power devices is electrically and mechanically connected directly between the second trace and a lower end of one of the second plurality of embossings in the second elongate rod of the second terminal assembly.

A hallmark of these designs is 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 needs without losing any of the performance benefits the package provides. Arrange these packages in parallel to increase the current of the converter and/or form topologies such as full-bridges (often used in DC-DC power conversion) and three-phase (used in motor drives and inverters). It is also easy to do.

As scalability and modularity are aspects of this product design, a broad portfolio of proposals and configurations can be supported by this platform. As described below, the present disclosure may be expanded or narrowed to best meet the needs of a particular application.

Those skilled in the art will appreciate the scope of this disclosure and will realize its additional aspects after reading the following detailed description in conjunction with the accompanying drawings.

The accompanying drawings, incorporated in and forming a part of this specification, illustrate several aspects of the disclosure and, together with the description, serve to explain the principles of the disclosure.
1A and 1B illustrate schematic diagrams of a conventional half (H)-bridge circuit.
FIG. 2 illustrates a practical implementation of the H(half)-bridge circuit of FIG. 1A.
3 is an isometric view of an external structure of a power module according to a first embodiment of the present disclosure.
4 is an isometric view of the internal structure of the first embodiment of the present disclosure.
5 is a plan view of the internal structure of the first embodiment of the present disclosure.
6 is an exploded view of a first embodiment of the present disclosure.
7 is a plan view of the internal structure of an alternative embodiment of the present disclosure.
8 illustrates an exemplary power loop for the first embodiment of the present disclosure.
9A illustrates a first embodiment of a terminal connection to a low inductance bus bar bottom layer according to the present disclosure.
9B illustrates a first embodiment of a terminal connection to a low inductance bus bar top layer according to the present disclosure.
9C illustrates a second embodiment of a terminal connection to a low inductance bus bar top layer according to the present disclosure.
10A illustrates a second embodiment of a terminal connection to a low inductance bus bar bottom layer according to the present disclosure.
10B illustrates a third embodiment of a terminal connection to a low inductance bus bar top layer according to the present disclosure.
11 illustrates an exemplary signal loop according to the first embodiment of the present disclosure.
12 illustrates direct bonding to a power substrate according to one embodiment of the present disclosure.
13 illustrates balancing current paths between devices due to transconductance mismatches.
14A and 14B are front and rear isometric views of an outer housing of a power module according to one embodiment of the present disclosure.
14c and 14d are top and cross-sectional views of the outer housing of the power module of FIGS. 14a and 14b.
15 illustrates the outline of a power module housing according to one embodiment of the present disclosure.
16A, 16B, 16C, and 16D illustrate various examples of signal pin assemblies according to the present disclosure.
17A and 17B illustrate examples of signal pin trimming according to the present disclosure.
18 illustrates lead frame features according to one embodiment of the present disclosure.
19A and 19B are isometric and top views of a lead frame section according to the present disclosure.
20 illustrates one embodiment of a lead frame array according to the present disclosure.
21 illustrates a larger variant for a power module according to the present disclosure.
22A and 22B illustrate fully dense power modules and partially dense power modules according to the present disclosure.
23 illustrates an example of parallelized power modules with laminated bussing to form a higher power half-bridge according to one embodiment of the present disclosure.
24 illustrates power modules arranged as a full-bridge topology according to one embodiment of the present disclosure.
25 illustrates power modules arranged as a three-phase topology according to one embodiment of the present disclosure.
26 illustrates power modules arranged as a three-phase topology with two power modules in parallel per leg, according to one embodiment of the present disclosure.
27 is a first isometric view of an external structure of a power module according to another embodiment of the present disclosure.
28 is a second isometric view of an external structure of a power module according to the embodiment of FIG. 27 of the present disclosure;
29 is an isometric view of an internal structure of a power module according to the embodiment of FIG. 27 of the present disclosure;
30 is a plan view of an internal structure of a power module according to the embodiment of FIG. 27 of the present disclosure.
31 is an exploded view of a power module according to the embodiment of FIG. 27 of the present disclosure.
32 is a third isometric view of the external structure of a power module according to the embodiment of FIG. 27 of the present disclosure, with the housing removed.
33A and 33B are isometric and top views of a lead frame section according to the present disclosure.
34 illustrates one embodiment of a lead frame array according to the present disclosure.
35 and 36 are first and second conformal diagrams illustrating a broader variant to a power module in accordance with the present disclosure, wherein a wider implementation supports additional power devices to the power module with higher power handling capabilities. help
37 and 38 are first and second illustrative narrower variations on a power module according to the present disclosure, where the narrower implementation supports fewer or smaller power devices for a power module with lower power handling capabilities. These are the second isometric views.

The embodiments presented below represent the information necessary to enable those skilled in the art to practice the embodiments, and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawings, those skilled in the art will understand the concepts of this disclosure and will recognize applications of these concepts not specifically addressed herein. It should be understood that these concepts and applications fall within the scope of this disclosure and appended claims.

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

When an element such as a layer, region, or substrate is referred to as being “on” or extending “onto” another element, it is directly on or on the other element. It will be appreciated that it may extend directly onto or intermediate elements may also be present. In contrast, when an element is referred to as being “directly on” another element or as extending “directly onto” another element, there are no intermediate elements present. Similarly, when an element such as a layer, region, or substrate is referred to as being “over” another element or extending “over” another element, it is directly on or over the other element. It will be appreciated that it may extend directly above or intermediate elements may also be present. In contrast, when an element is referred to as being “directly over” another element or as extending “directly over” another element, there are no intermediate elements present. It will also be understood that when an element is referred to as being “connected” or “coupled” to another element, it is directly connected or may be coupled to that other element or intervening elements may be present. . In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intermediate elements present.

“Below” or “above” or “upper” to describe the relationship of one element, layer, or region to another element, layer, or region as illustrated in the drawings. Or relative terms such as "lower" or "horizontal" or "vertical" may be used herein. It will be appreciated 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.

The terms used herein are for the purpose of describing specific embodiments only, and are not intended to limit the present disclosure. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly dictates otherwise. The terms “comprises,” “comprising,” “includes,” and/or “including”, when used herein, refer to stated features, integers, steps, operations, elements, and/or It will be further understood that specifying the presence of components does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Unless defined otherwise, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terms used in this specification are to be construed to have a meaning consistent with their meaning in the context of this specification and related art, and are to be interpreted in an idealized or overly formal sense, unless expressly so defined herein. It will be further understood that it will not be.

The present disclosure relates to power modules used in high power applications. Power modules 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 into various circuit topologies. Common circuit topologies include, but are not limited to, a single switch, a half (H)-bridge circuit, a full H-bridge circuit, and a 3-phase switching circuit, often referred to as a 6-pack.

For the following discussion, a half-bridge circuit is used to facilitate understanding of the packaging concepts disclosed herein. A basic half (H)-bridge circuit is a common power circuit used to switch different voltages to a load, such as a motor as illustrated in FIGS. 1A and 1B. The main components of the H(half)-bridge circuit are the high-side transistor Q1 and the low-side transistor Q2, connected in series between the V+ terminal and the V- terminal. Assume for this example 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 connected to the V+ terminal and the source (S) of transistor Q2 is connected to the V- terminal. The source of transistor Q1 and the drain of transistor Q2 are connected together and represent the MID terminal, which is essentially an output node connected to a load (not shown).

To increase power handling, multiple power devices can be connected in parallel with each other. In the illustrated embodiments and as depicted in Figure 2, transistor Q1 is represented by three transistors Q1', Q1'', and Q1''' connected in parallel with each other, and transistor Q2 in parallel with each other. It is represented by the connected three transistors Q2', Q2'' and Q2'''. For 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 It may be referred to as transistor Q2. In this example, transistors Q1 and Q2 are vertical, N-channel MOSFETs, the drain contact is on the bottom of the device, and the source, gate, and source-Kelvin contacts are on the top of the device. The half (H)-bridge circuit of FIG. 2 is implemented in power module embodiments described below, but is only one of many types of circuits that will benefit from the concepts presented herein.

An exemplary power module 10 is illustrated in FIGS. 3, 4, 5, and 6 according to a first embodiment. 3 is an isometric view of the power module 10 with the housing 12, which may be molded. 4 and 5 are isometric and plan views of the power module 10 without the encapsulated molded housing 12 . 6 is an exploded view of power module 10 . The following description refers collectively to each of FIGS. 3 , 4 , 5 , and 6 .

At the core of the power module 10 is a substrate 14 with power devices 16 mounted on its top surface. In this embodiment, power devices 16 are transistors Q1 (ie, Q1', Q1", Q1"') and Q2 (ie, Q2', Q2", Q2'''). A first terminal assembly, referred to as V-terminal assembly 18, is mounted over transistor Q2 (16) proximate side A of power module 10. The V-terminal 18 assembly is conductive and attached directly to the source contacts on the top side of transistors Q2 to form the V-node of FIG. 2 .

The two opposite terminals, referred to as V+ terminal assemblies 22, are mounted to a first trace/pad 34 (FIG. 6) on the top surface of the board 14 proximate sides C and D. Transistors Q1 are mounted on substrate 14 such that the drains of transistors Q1 are directly attached to first trace/pad 34 . As such, the drains of transistors Q1 and the V+ terminal assemblies 22 form the V+ node of FIG. 2 .

Another terminal assembly, referred to as MID-terminal assembly 20, is mounted over transistor Q1 (16) proximate side B of power module 10. The MID-terminal assembly 20 is conductive and attaches directly to the source contacts on the top side of the transistors Q1. MID-terminal assembly 20 includes integral jumpers 20J extending to and attached directly to second trace/pad 34, to which drain contacts of transistors Q2 are directly attached. As such, the drain contacts of transistors Q2, source contacts of transistors Q1, and MID-terminal assembly 20 form the MID node of FIG.

Gate and source-Kelvin contacts G1 and K1 for transistors Q1 are electrically connected to pin assemblies 24 and 26 using bond wires 32, respectively. Similarly, gate and source-Kelvin contacts G2 and K2 for transistors Q2 are electrically connected to pin assemblies 28 and 30 using bond wires 32, respectively. The pin assemblies 24, 26, 28 and 30 are mounted directly to the top surface of the substrate 14 such that they are electrically isolated from each other and from the high power V-, V+, MID-nodes. Details regarding the design and shape of pin assemblies 24, 26, 28, 30, V- terminal assembly 18, inverse MID-terminal assembly 20, and V+ terminal assemblies 22 are provided below. additionally provided. In particular, these designs may include additional pins or pin assemblies that provide input or output nodes for the electronics provided by power module 10 . These additional pins and pin assemblies may be used for current sensing, temperature sensing, biasing, and the like.

Reference is now made to an exploded view of power module 10 in FIG. 6 . Starting at the bottom of the figure, power devices 16, including transistors Q1 and Q2, are attached to first and second traces 34, at mounting locations 38 using device attachment material 40. 36) is attached. The device attachment material 40 may be a solder, adhesive, sintered metal, or the like that provides mechanical structures, high current interconnects, and high thermal conductivity.

Pin assemblies 24, 26, 28, 30, V- terminal assembly 18, MID-terminal assembly 20, and V+ terminal assembly 22 are formed from a single lead frame 44. The top portions of power devices 16 and substrate 14 are connected to V- terminal assembly 18, MID-terminal assembly 20, and V+ terminal assemblies 22 using lead frame attachment material 42. It is connected to the corresponding lower portions of. The lead frame attachment material may be solder, adhesive, sintered metal, laser welding, ultrasonic welding, etc., which provides mechanical structure, high current interconnection, and high thermal conductivity. Lead frame 44 is typically a metal contact strip for high current external connections and internal interconnections. Random contacts are joined together on a single sheet, often with multiple products per sheet, and processed as an array before being formed and singulated.

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

Housing 12 may be formed using a transfer or injection molding process to provide mechanical structure, high voltage isolation. Housing 12 encapsulates the internal components of power module 10 . The molding compound used for housing 12 can 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.

The V-terminal assembly 18 includes an elongated first rod 18B present between the two terminal legs 18L. Together, the elongated first rod 18B and the two terminal legs 18L form a U-shape in the illustrated embodiment. Other shapes are envisioned, such as T, V and C-shapes. Each of the terminal legs 18L extends outward from the first rod 18B toward the side A of the power module 10, passes through the side surface of the housing 12, and upwards toward the top of the housing 12. It is shaped to rotate and then rotate inwardly over a portion of the top of housing 12 to provide a V-terminal contact 18C. In this way, the distal portion of each of the terminal legs 18L is bent backward over its middle portion. As noted above, the bottom portions of the first bar 18B of the V-terminal assembly 18 are directly attached to the source contacts of the transistors Q2 (power devices 16). Embossings E (not shown) may be provided as described in embodiments described further below. V-terminal contacts 18C at exposed distal ends of terminal legs 18L provide terminal contacts for first terminal assembly 18 .

Similarly, the MID-terminal assembly 20 includes an elongated second bar 20B present between the two terminal legs 20L. Together, the second rod 20B and the two terminal legs 20L form a U-shape in the illustrated embodiment. Other shapes are envisioned, such as T, V and C-shapes. Each of the terminal legs 20L extends outward from the end of the second rod 20B toward the side B of the power module, passes through the side surface of the housing 12, and rotates upward toward the top of the housing 12. and then rotated inwardly over a portion of the top of the housing 12 to provide a MID-terminal contact 20C. In this way, the distal portion of each of the terminal legs 20L is bent backward over its middle portion. The lower portions of the second bar 20B of the MID-terminal assembly 20 are directly attached to the source contacts of the transistors Q1 (power devices 16). Embossings E (not shown) may be provided as described in embodiments described further below. The exposed distal ends of the second terminal legs 30 provide terminal contacts for the second terminal assembly 20 .

The MID-terminal assembly 20 in this embodiment includes a plurality of (three) integrally formed jumpers extending from the second bar 20B toward the first bar 18B of the first terminal assembly 18. s 20J are also included. The distal ends of jumpers 20J are attached directly to first trace 34 on the top surface of substrate 14, as described above. Jumper 20J may be replaced with a single bar. Additionally, the number of jumpers 20J may vary from embodiment to embodiment. In certain embodiments, there will be one jumper 20J per power device 16 connected to MID-terminal assembly 20 .

The two opposite V+ terminal assemblies 22 are shaped similarly to the terminal legs 18L and 20L of the first and second terminal assemblies 18 and 20, respectively. Other shapes are envisioned. One end of each opposite terminal 22 is attached directly to the second trace 36 on top of the substrate 14 . From the board 14, each opposite terminal 22 extends outward toward sides C and D of the power module 10, passes through each side of the housing 12, and the top of the housing 12. and then rotated inward over a portion of the top of the housing 12 . As such, the distal portion of each of the V+ terminal assemblies 22 is bent back over its middle portion. The exposed terminal ends of opposite terminals 22 provide terminal contacts 22C for V+ terminal assemblies 22 . As illustrated, V- and MID- terminal assemblies 18 and 20 are located on opposite sides A and B of power module 10 . Two opposite V+ terminal assemblies 22 are located on the remaining opposite sides C and D of power module 10 . In particular, the V-, V+ and MID terminal contacts 18C, 22C, 20C may be coplanar or non-planar depending on the application. V-, V+, and MID terminal contacts 18C, 22C, 20C can also be formed in different configurations, some with two bends to form a C shape while some with one forming an L, etc. can only have curvatures of Non-planar configurations that place contacts on two, three or more different planes may provide additional options for connecting these contacts to external bus rods.

Groups of nested signal pin assemblies 24, 26 and 28, 30 are formed between the terminal legs 18L of the V-terminal assembly 18 and the terminal legs 20L of the MID-terminal assembly 20. is provided on Pin assemblies 24, 26, 28, 30 in the illustrated embodiment are U-shaped and from pin rods 24B, 26B, 28B, 30B and respective pin rods 24B, 26B, 28B, 30B. It includes a pair of extending pin legs 24L, 26L, 28L, 30L. Other embodiments may use L and T shapes for the signal pin rods 24B, 26B, 28B, 30B. Pin legs 24L, 26L, 28L, 30L extend outward through each side of housing 12 and rotate vertically upward. Bond wires 32 electrically connect power devices 16 to pin rods 24B, 26B, 28B, 30B of pin assemblies 24, 26, 28, 30.

Generally, there are two categories of electrical loops in a power module: power loops and signal loops. The power loop is a high voltage, high current path through the transistors Q1, Q2 to deliver power to the load through the drain (or collector) and source (or emitter) of the transistors Q1, Q2, and the load is connected to the MID-terminal assembly ( 20) is normally connected. The signal loop is a low voltage, low current path through gates G1, G2 (or bases) and sources S (or emitters) of transistors Q1, Q2. The gate-source (or base-emitter) signal path activates the transistors Q1 and Q2 to actually turn them on or off. As described in detail below, the signal loop may also involve the source-Kelvin connections K1, K2 of transistors Q1, Q2.

The power loop continues substantially between the V+ terminal assembly 22 and the V- terminal assembly 18 . V+ terminal assembly 22 and V- terminal assembly 18 are typically connected across a DC power source, such as a battery, in parallel with a large capacitance. An exemplary power loop for the illustrated power module 10 is shown in FIG. 8 .

Opposite V+ terminal assemblies 22 are attached directly to opposite ends of second trace 36 on board 14 . Power flows into power module 10 through legs 22C and contacts 22C of two V+ terminal assemblies 22 . As such, power flows through the terminal assemblies 22 onto the opposite ends of the second trace 36 on the substrate 14 and over the drain contacts of the transistors Q1. The drain contacts of transistors Q1 are at the bottoms of transistors Q1 and are also directly attached to the second trace 36 . Transistors Q1 are attached to the second trace 36 between the points at which the two V+ terminal assemblies 22 are attached to the second trace 36, the transistors Q1 being away from each other and the two V+ terminal assemblies Equally spaced from the attachment points to (22).

Power then flows through transistors Q1 from the drains of transistors Q1 to the sources of transistors Q1. The sources of the transistors Q1 are attached to the lower side of the second rod 20B of the mid terminal assembly 20. The mid-terminal jumpers 20J of the mid-terminal assembly 20 connect the second rod 20B of the mid-terminal assembly 20 to the first trace 34 on the substrate 14 . The drains of transistors Q2 are directly attached to first trace 34 and equally spaced from each other. From the drains of transistors Q2, power flows through transistors Q2 to the sources of transistors Q2. The sources of transistors Q2 are directly connected to the bottom side of first rod 18B of V-terminal assembly 18 . As such, power flows along first rod 18B and through opposing legs 18L to contacts 18C of V-terminal assembly 18 .

Using symmetrical V+ terminal assemblies 22 and symmetrical V- terminal assembly 18, current sharing between devices is balanced and smaller external contacts can be used, which helps with lead frame panelization, and power By shortening the entire current path in the loop, the inductance is greatly reduced. As described further below, contacts 18C, 20C, 22C of V- terminal assembly 18, MID-terminal assembly 20, and V+ terminal assemblies 22 may be laser welded, solder , ultrasonic welds, mechanical bonds (clamps, springs, etc.), conductive adhesives, or any other conductive bond.

Current must flow through a closed circuit. Thus, the stray inductance of the package itself is not the only factor contributing to the overall loop inductance. Any capacitance of the power supply and inductance of the entire loop, including capacitors provided across the power supply, external busings and wiring, and the power module 10 itself, must be considered. In this way, not only must the internal layout of the power module 10 be low-inductance, but also the positions of the V- terminal assembly 18, the MID-terminal assembly 20, and the V+ terminal assemblies 22 are low-inductance laminated. A busing or similar interconnection method of connecting power module 10 to a DC power source should also be allowed.

There are many effective approaches to connecting terminals to high performance bussing. 9A and 9B depict an approach using laminated bus bars: V- bus bar 48, MID bus bar 50, and V+ bus bar 52, respectively, V- terminal assembly 18 ), MID-terminal assembly 20, and V+ terminal assemblies 22. As such, the metal planes for busing continue over the top of the power module 10 . For clarity, only the metal components of V- bus rod 48, MID bus rod 50, and V+ bus rod 52 are shown, and the lamination film itself is not shown. The illustrated configuration provides a high density and low inductance solution in which neighboring power modules 10 can be placed in close proximity to each other, such as to parallelize or form a multi-module topology.

Referring specifically to FIG. 9A , the V-bus bar 48 has a body 48B from which two contacts 48C extend. Contact 48C is physically and electrically connected to contacts 18C of V-terminal assembly 18 . Similarly, the MID bus bar 50 has a body 50B from which two contacts 50C extend. The contacts 50C are physically and electrically connected to the contacts 20C of the MID terminal assembly 20 . Referring to Fig. 9B, the V+ bus rod 52 has a body 52B from which a single wide contact 52C extends. Contact 52C is physically and electrically connected to contacts 22C of opposing V+ terminal assemblies 22 . An opening in V+ bus bar 52 provides access to contacts 48C of V- bus bar 48 as well as passage to pin assemblies 28, 30 for gate G2 and source-Kelvin K2 signals. . FIG. 9B shows bending of the V+ bus rod 48, which can be avoided in some circumstances by lifting the V+ terminal assemblies 22 up so that they are not co-planar with the V- terminal assemblies 18. show

9C provides an alternative configuration for the V+ bus bar 52.

V+ bus bar 52 has an extension 52E extending from body 52B. The body has two opposing pits 52F descending from extension 52E to contacts 22 of V+ terminal assemblies 22 . The configuration of FIG. 9C sacrifices some inductance (i.e. increased inductance due to less lamination area) slightly in exchange for more strain relief and less stiffness relative to the configuration of FIG. 9B.

Another busing approach is illustrated in FIGS. 10A and 10B. Here, bussing continues more along the sides of the power modules 10 or around their perimeter. This may be useful in situations where more access to contact areas or power module 10 is needed in general. For example, this is the case where a soldering or welding tool needs to directly touch the metal surfaces of the various contacts.

Referring specifically to FIG. 10A, the V-bus rod 48' has a body 48B' from which two contacts 48C' extend. V-bus rod 48' is biased out of the perimeter of power module 10, and two contacts 48C' are inward and out to make contact with contacts 18C of V-terminal assembly 18. It wraps around opposite sides of the power module 10 before extending downward. Similarly, the MID bus rod 50' has a body 50B' from which two contacts 50C' extend.

The MID bus bar 50' is biased outside the perimeter of the power module 10 where the two contacts 50C' are inward and out to make contact with the contacts 20C of the MID-terminal assembly 20. It wraps around opposite sides of the power module 10 before extending downward.

Referring to FIG. 10B, V+ bus bar 52' is biased outside the perimeter of power module 10 and resides above V- bus bar 48'. A V+ bus bar 52' wraps around opposite sides of the power module 10 before extending inward and downward to make contact with contacts 22C of each of the V+ terminal assemblies 22. It has contacts 52C'. More busing approaches and module variations can be envisioned depending on the specific system configurations. Ultimately, the end goal is to provide a versatile and effective terminal arrangement that allows for a variety of end user solutions.

The signal loops or gate and sources connections, for each transistor Q1, Q2 location, also benefit from low impedance which minimizes the voltage stress on the gates of transistors Q1, Q2 during switching. Gate stresses can be buffered or reduced by adding resistors, but this often comes at the cost of higher package complexity, higher cost, and slower switching speeds. Most importantly, for optimal switching performance, the power loops and signal loops are completely independent of each other, enabling low switching losses with high speed and well-controlled dynamics.

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. When the power path is connected to the signal paths, additional dynamics are introduced through positive or negative feedback. Typically, negative feedback introduces additional losses as the power path connection fights the control signal (ie, when the control signal tries to turn the device on and the power path connection tries to turn the device off). Positive feedback usually causes instability, as the power path connection amplifies the control signal until the device is destroyed. Ultimately, the coupling of the power and signal paths results in a reduction in switching quality, slower switching speeds, increased losses, and possible destruction.

Thus, independent loops improve switching quality. In the illustrated embodiments, the power connections have separate paths from the signal sources (referred to as source-Kelvin) so that one does not overlap or interfere with the other. The closer the discrete connections to the transistors, the better the switching performance.

11 illustrates inner signal loops for the illustrated embodiment. The signal loop for transistor Q1 flows onto and through G1 pin assembly 24 and then through bond wire 32 to the gate contact of transistor Q1, where the signal is presented to transistor Q1. A signal loop flows from transistor Q1 through the source contact of transistor Q1. From the source contact, the signal loop flows through another bond wire 32 directly to and through the K1 pin assembly 26 .

Similarly, the signal loop for transistors Q2 flows onto and through G2 pin assembly 28 and then through bond wire 32 to the gate contact of transistors Q2, and the signal is presented to transistors Q2. A signal loop flows from transistor Q2 through the source contact of transistor Q2. From the source contact, the signal loop flows through another bond wire 32 directly to and through the K2 pin assembly 30 . As shown, this is a true source-Kelvin implementation in which the power and signal loops are completely independent.

The signal loops in FIG. 11 are just one example. As shown in FIG. 12 , other embodiments may include additional signal traces 54 on top of the substrate 14 . In these embodiments, one set of bond wires 32 first connects the transistor's gate and source contacts to additional signal traces 54, and a second set of bond wires 32 connects these additional signal traces. Connect traces 54 to appropriate pin assemblies 24-30 (G1, G2, K1, K2). The latter configuration allows for a simpler signal pin implementation, but requires significantly more board area, which can 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.

A further issue arises from transconductance mismatch between parallelized devices. Transconductance is effectively the current gain of the device and corresponds to the relationship between the output current and the input voltage. During switching, the input voltage rises, resulting in an associated rise in output current. When there is a difference in transconductance between paralleled devices, which is common in silicon carbide power devices, the devices each have slightly different turn-on characteristics. Due to the different currents going through the devices, slightly different voltages are presented to each device. These voltage mismatches will result in 'balancing current' flowing between the devices during switching.

This balancing current will favor the path of least impedance, which can be through the signal loop instead of the power loop. Like interference issues with connected power and signal loops, this balancing current can affect switching quality. Introducing such high uncontrolled current through the signal loop may also introduce reliability concerns since the signal loops are not intended to carry high current.

In one embodiment, a significantly lower inductance is found through a metal sheet that continues across the source pads on the top side of the devices. These pathways are depicted in FIG. 13 . In comparison, the effective path length and cross section of the source bond path have a relatively higher impedance. In practice, the balancing current flows through the power contacts and does not interfere with the signals.

Referring now to FIGS. 14A-14D , the package is encapsulated by a protective plastic or epoxy housing 12 via transfer molding, compression molding, injection molding, or a similar process. Some notable features of housing 12 are highlighted in FIGS. 14A-14D and discussed below. As shown in FIG. 14B , the backside metal of the power substrate 14 is exposed on the underside of the power module 10 to provide a thermal pad 56 . Thermal pad 56 is used as a thermal contact surface to remove heat from power module 10 . Thermal pad 56 may be sintered, soldered, epoxidized, or similarly attached to a heat sink or cooling plate (not shown) to further aid in the removal of waste heat from power module 10 .

Features in the housing may vary based on manufacturing method. The embodiments of FIGS. 14A-14D represent structural characteristics of transfer molding. Four retaining pin marks 57 are shown, but may be more or fewer depending on the overall size of the power module 10 . Securing pins (not shown) press directly against the power substrate during the transfer molding process to limit the amount of plastic bleed or flash on the exposed portion of the thermal pad 56 . This ensures that the thermal surface is free of debris and that the thermal surface can serve to efficiently remove heat. There are also ejector marks 58 around the perimeter of the housing 12 . Ejector marks 58 are small recesses created by ejector pins (not shown) used to remove power module 10 from mold (not shown) while still hot. The specific locations of these features and associated geometries will vary depending on the specific product size and implementation.

Clearance and creepage can be important aspects for high voltage products. Between conductors of different voltage potentials, clearance is the shortest direct path in air between the conductors. Creepage is the shortest direct path along a surface between conductors. Meeting safety standards is a challenge, often at odds with manufacturing methods (pores, 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 reach the right balance.

In certain embodiments, clearance distances are sufficient and within standards. To increase the creepage distance and correspondingly increase the maximum allowed voltage, creepage extenders 60 are used. Creepage extenders 60 are grooves, ripples, or other surface enhancements that extend the surface distance between conductors of different voltage potentials. As illustrated, creepage extenders 60 are included as part of the plastic or epoxy housing 14 to provide additional functionality without adding cost. 14C and 14D show one implementation of these features on housing 12 of power module 10 . Other patterns are possible on the top and back faces depending on the particular design implementation.

In order to minimize the length of the power loop, some or all of the edge power contacts, such as those for the V- and MID-terminal assemblies 18, 20, as shown in FIG. 24, 26, 28, 30), compared to the signal contacts, can be inserted from the edge of the housing 12. The signal contacts provided by the pin assemblies 24, 26, 28, 30 require more space to better accommodate the bond wires 32 from the devices; Thus, their housing sections extend outwardly from the edge of the entire housing 12 . This contour feature allows inductance optimization for each of the independent power and signal loops.

Pin assemblies 24, 26, 28 and 30 continue along the horizontal strip to accommodate devices in parallel. Externally, there are many ways to form the pins of the contacts, to which printed circuit board gate drivers, wires, or the like will be attached. Some variations are depicted in FIGS. 16A-16D. For brevity and clarity, only pin assemblies 28 and 30 are discussed, but the same concepts apply to pin assemblies 24 and 26 as well.

A first approach is shown in FIG. 16A , where the pin assemblies 28 and 30 are U-shaped and concentric as described above. In these embodiments, the legs of the pins go out of the respective side portions of the housing and then rotate 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.

The first approach exploits product symmetry. Depending on where pin assemblies 28 and 30 exit housing 12, holes 30H in pin rod 30B of outer pin assembly 30 provide strain relief. The second approach presented in FIG. 16B does not include holes for strain relief. Instead, strain relief is inherent in the pin rod 30B because it is U-shaped and allows some portion of the housing 12 to be present in the U-shaped bend of the pin assemblies 28, 30. In other approaches, three pins may be used as shown in FIGS. 16C and 16D. In these approaches, the outer pin assembly 28 maintains a U-shape with two legs 28L. However, the centrally located inner pin assembly 30 only has a single leg 30L. Rods 30B for pin assembly 30 can take almost any shape, such as a prismatic or triangular shape in FIG. 16C or a T-shape in FIG. 16D.

Depending on the specific needs of the final system and the format of its gate driver, there are many more pin assembly variations that can be considered. The illustrated embodiments were developed with modularity and flexibility in mind, enabling numerous potential product variations.

Other pin modifications include trimming some of the legs from pin assemblies 24, 26, 28, 30, as illustrated in FIGS. 17A and 17B. For example, by removing one leg from pin assemblies 24, 26, 28, 30 so that the gate and/or source-Kelvin driver on the PCB is connected to two of the contacts (as opposed to four in the previous embodiment). Only dogs are allowed to be used. Asymmetric approaches can be useful in maximizing the amount of metal area used by external bussing. In FIG. 17A , inner pin assemblies 26 and 30 have both legs 26L and 30L, respectively. The outer pin assemblies 24, 28 have one leg trimmed to retain only one leg 24L, 28L for each of the pin assemblies 24, 28. 17B, both inner pin assemblies 26, 30 and outer pin assemblies 24, 28 have only one leg 24L, 26L, for pin assemblies 24, 26, 28, 30, respectively. 28L, 30L) and has one leg that is trimmed to retain only.

As noted above, terminal and pin assemblies 18-30 are formed from lead frame 44 and combine the functionality of providing high current internal interconnections, bond wire locations, and external terminal contact surfaces. Parts or parts of lead frame 44 are attached to both substrate 14 as well as top source pads of transistors Q1 and Q2. Lead frame 44 may be attached to various components in several ways, including soldering, sintering, conductive epoxy, laser welding, ultrasonic welding, and the like. Surface enhancement features, such as holes, slots, feathered edges, '? Also referred to as 'solder or epoxy catches', as shown in FIG. 18, it can be used to reinforce the strength of a bond.

A strip on the lead frame 44 that is directly attached to the top surface source pads may have several distinguishing features. Depending on the specific layout of the device being packaged, there may be a variety of solder catch implementations. Additionally, ripples (not shown) between devices for thermal expansion stress relief and enhanced molding flow may be included. Various bends of the lead frame 44 may be used as an additional means of stress relief.

Outside the power module 10, the terminal and pin assemblies 18-30 are attached to bus rods, wires, printed circuit boards, and the like. Vibration in the system can pull the terminal and pin assemblies 18-30. It is desirable to ensure that these external forces do not push or pull the power devices or bond wires. To this end, if necessary, holes and/or other retaining features are placed in the lead frame 44 so that when pulled, the molding compound filling these holes, rather than the sensitive internal components, undergoes deformation.

The holes 62 and/or other retaining features of the lead frame 44 are positioned to mate with the position of the securing pins used in the transfer molding process. Ideally, these pins press directly into the substrate. These holes 62 provide clearance for the pin to accomplish this. They also serve as strain relief after the assembly is molded.

Lead frame 44 may be made of sheet metal in an etching or stamping process. One example of this is presented in FIGS. 19A and 19B . The contacts and inner features are joined to the outer frame by narrow tabs. To streamline processing in panels or magazines, much of the sheet metal starts out flat. Only internal bends are formed. Due to the multiple heating processes required by the assembly during manufacturing production, thermal expansion slots are added to break large copper areas. These limit expansion and warping of the assembly.

A lead frame 44 is attached to the power devices and the substrate, wire bonded, then shaped and then trimmed away from the outer frame at the locations of the joining tabs. The folds of the outer contacts are formed by folding, often with procedural steps and optional trimming.

For automated mass production, these lead frames 44 are often patterned into an array. These arrays are handled on multiple machines, often loaded from magazines or racks. Holes on the top and bottom edges are used for fixturing, positioning, keying, and handling. An exemplary lead frame array 64 with four lead frames 44 is shown in FIG. 20 . The specific features of lead frames 44 and lead frame array 64 will vary depending on product configuration, product size variations, and types of manufacturing equipment.

A potential benefit of the illustrated embodiments is the ability to expand or contract the main layout 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 widths and lengths at various counts by parametrically increasing in the relevant dimensions. In particular, scaling the power module 10 in this way will not reduce or limit the key benefits of the basic packaging approach. Examples of scalability are presented in FIGS. 5 and 21 , FIG. 5 illustrates a power module 10 having three transistors Q1 (16) and three transistors Q2 (16), and FIG. 21 is six transistors. Illustrates a laterally elongated power module 10 having Q1(16) and six transistors Q2(16).

In certain embodiments, a shared set of materials is desired to minimize the number of unique production tools required to manufacture a component. As such, an alternative form of scalability is to maintain the same substrate and lead frame layout and adjust the number or scale of devices in a set footprint. For example, devices can be wider (higher current) in some cases and narrower (lower cost) in other cases. The locations may also be non-dense to reduce peak power handling compared to fully dense power modules 10 . An example is provided in FIGS. 22A and 22B. The power modules 10 of both FIGS. 22A and 22B are laterally stretched relative to that provided in FIG. 5 to have five locations for transistor Q1 (16) and five locations for transistor Q2 (16). lose The power module 10 of FIG. 22A is fully populated with five transistors Q1 (16) and five transistors Q2 (16). The power module 10 of FIG. 22B is packed with three transistors Q1 (16) and three transistors Q2 (16). Thus, assuming that two of the locations of FIG. 22B (non-dense locations 70) are intentionally left non-dense, and that the same type of components are used in both scenarios, Compared to this, it can correspond to a 40% reduction in power handling. In certain embodiments, only one transistor (Q1(16)) and one transistor (Q2(16)) are used.

Extensibility features allow within-package optimization. Likewise, providing a design that can be externally hardened or optimized is also helpful. The half-bridge legs of power module 10 can be arranged to form many topological variations. In most cases each of the respective V- and V+ terminal assemblies 18, 20 will be connected to the same low inductance bus rods. Mid-terminal assemblies 22 or AC output can be (1) connected to parallel packages for higher currents, (2) kept separate for individual bridge legs, or (3) both You can have some combination.

23 shows the V-, V+, and MID-terminal assemblies of the three power modules 10A, 10B, and 10C, respectively, with an elongated V- bus bar (not shown), an elongated V+ bus bar 72, and an elongated V+ bus bar 72. An example of a parallelized configuration is illustrated with laminated busings connected in parallel to long MID bus rods 74. The number of power modules 10X in parallel may be increased or decreased to suitably or best match the power requirements of the system. This feature allows the same core product to be used in a cost-effective manner in many systems of all power levels.

24 illustrates an example of two half-H bridge power modules 10A and 10B connected to form a single full H-bridge circuit using suitable busing. As illustrated, the V- terminal assembly (not shown) and the V+ terminal assembly 22 of the two power modules 10A and 10B include an elongated V- bus bar (not shown) and an elongated V+ bus bar (not shown). 72) are connected in parallel to each other. A first MID-bus bar 74A is provided for the MID-terminal assembly 20 of the power module 10A, and a second MID-bus bar 74B is provided for the MID-terminal assembly 20 of the power module 10B. ) is provided for.

25 illustrates a three-phase topology with three bridge legs and using laminated busings. Three power modules 10A, 10B and 10C are provided. The V- terminal assembly (not shown) and V+ terminal assembly 22 of power modules 10A, 10B, and 10C are connected to an elongated V- bus bar (not shown) and an elongated V+ bus bar 72. connected in parallel to each other. A first MID-bus bar 74A is provided for the MID-terminal assembly 20 of the power module 10A, and a second MID-bus bar 74B is provided for the MID-terminal assembly 20 of the power module 10B. ), and a third MID-bus bar 74C is provided for the MID-terminal assembly 20 of the power module 10C.

The concepts presented in FIGS. 23 and 24 can be combined. 26 shows an arrangement using laminated busing to provide three bridge legs with two power modules 10 in parallel per bridge leg. Specifically, power modules 10A and 10B are connected in parallel for a first leg, power modules 10C and 10D are connected in parallel for a second leg, and power modules 10E and 10F are 3 connected in parallel to the third leg using two MID-bus rods 74A, 74B, and 74C.

Another exemplary power module 100 incorporating certain of the concepts described above is illustrated in FIGS. 27-32 . 27 is an isometric view of the top of power module 100 with housing 112. 28 is an isometric view of the bottom of the power module 100 . 29 and 30 are isometric and top views of the bottom of the power module 100 without molded housing 112 . 31 is an exploded view of power module 100 . The following description collectively refers to each of FIGS. 27-31 .

At the core of power module 100 is a substrate 114 to which power devices 116 are mounted to its top surface. In this embodiment, the power devices 116 are transistors Q1 (ie, Q1', Q1", Q1"') and Q2 (ie, Q2', Q2", Q2'''). V-terminal assembly 118 in this embodiment is still mounted over transistors Q2 116 proximate side A of power module 100. V-terminal assembly 118 is conductive and is directly attached to the source contacts on the top side of transistors Q2 to form the V-node of FIG. 2 . In this embodiment, four Q1 transistors and four Q2 transistors are illustrated; 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 .

Two opposite V+ terminal assemblies 122 are mounted to a first trace/pad 134 (FIG. 31) on the top surface of the substrate 114 proximate sides C and D. Transistors Q1 are mounted on substrate 114 such that the drains of transistors Q1 are directly attached to first trace/pad 134 . As such, the drains of transistors Q1 and the V+ terminal assemblies 122 form the V+ node of FIG. 2 .

MID-terminal assembly 120 is mounted over transistors Q1 116 proximate side B of power module 100 . MID-terminal assembly 120 is conductive and attaches directly to the source contacts on the top side of transistors Q1. MID-terminal assembly 120 includes integral jumpers 120J extending to and attached directly to second trace/pad 136, to which drain contacts of transistors Q2 are directly attached. As such, the drain contacts of transistors Q2, source contacts of transistors Q1, and MID-terminal assembly 20 form the MID node of FIG.

Gate and source-Kelvin contacts G1 and K1 for transistors Q1 are electrically connected to pin assemblies 124 and 126 using bond wires 132 , respectively. Similarly, gate and source-Kelvin contacts G2 and K2 for transistors Q2 are electrically connected to pin assemblies 128 and 130 using bond wires 132, respectively. The pin assemblies 124, 126, 128 and 130 are mounted directly to the top surface of the substrate 114 such that they are electrically isolated from each other as well as from the high power V-, V+, MID-nodes. Details regarding the design and configuration of pin assemblies 124, 126, 128, 130, V- terminal assembly 118, inverse MID-terminal assembly 120, and V+ terminal assemblies 122 are provided below. additionally provided. In particular, these designs may include additional pins or pin assemblies that provide input or output nodes for the electronics provided by power module 100 . These additional pins and pin assemblies may be used for current sensing, temperature sensing, biasing, and the like.

Reference is now made to an exploded view of power module 100 in FIG. 31 . Starting at the bottom of the figure, power devices 116, including transistors Q1 and Q2, are attached to first and second traces 134, at mounting locations 138 using device attachment material 140. 136) is attached. The device attachment material 140 may be a solder, adhesive, sintered metal, or the like that provides mechanical structures, high current interconnects, and high thermal conductivity.

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

The top portions of power devices 116 and substrate 114 are connected to V- terminal assembly 118, MID-terminal assembly 120, and V+ terminal assemblies 122 using lead frame attachment material 142. It is connected to the corresponding lower portions of. As noted above, the lead frame attachment material 142 may be solder, adhesive, sintered metal, laser welded, ultrasonic welded, or the like, which provides a mechanical structure, high current interconnection, and high thermal conductivity. Lead frame 144 is typically a metal contact strip for high current external connections and internal interconnections. Random contacts are joined together on a single sheet, often with multiple products per sheet, and processed as an array before being formed and singulated.

Bond wires 132 are typically used to connect control contacts of power devices 116 to various pin assemblies 124 , 126 , 128 , 130 . The bond wires 132 may be ultrasonic or thermosonic bonded large diameter wires capable of supporting relatively high current electrical interconnections. Alternatively, pin assemblies 126 , 126 , 128 , 130 may be directly bonded to power devices 116 , traces on substrate 118 , and the like. Since the pin assemblies 118' and 120' are integral with and are essential extensions of the respective V-terminal assembly 118 and MID-terminal assembly 120, no bond wires are needed for these connections.

Housing 112 may be formed using a transfer or injection molding process to provide mechanical structure and high voltage isolation. Housing 112 encapsulates the internal components of power module 100 . The molding compound used for housing 112 can 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.

Referring now generally to FIGS. 27-32 and to FIGS. 29 and 30 in particular, the V-terminal assembly 118 includes an elongated first rod 118B residing between two terminal legs 118L. . A notable difference between power module 10 and power module 100 described above is that V- terminal assembly 118 has V- terminal contacts 118C that are V+ terminal contacts of V+ terminal assemblies 122. that it is reconstructed to be positioned on the same sides as (122C). This configuration is slightly more optimized bus bar (bus bar 118B) with more overlap with power devices 116 (Q2) and less in-circuit inductance than using power module 10 described above. )) can be provided. In the power module 10, the V-terminal contacts 18C were both positioned on one side opposite to that of the MID-terminal contacts 20C of the MID terminal assembly 20.

In particular, each of the terminal legs 118L passes through one side of the housing 112 as they extend outward from the first bar 118B toward opposite sides C and D of the power module 100. , rotates upward toward the top of housing 112, and then rotates inward over a portion of the top of housing 112 to provide respective and opposite V-terminal contacts 118C. As such, the distal portion of each of the terminal legs 118L is bent back over its middle portion. The bottom portions of first rod 118B of V-terminal assembly 118 are directly attached to the source contacts of transistors Q2 (power devices 116). V-terminal contacts 118C at exposed distal ends of terminal legs 118L provide terminal contacts for V-terminal assembly 118 .

The MID-terminal assembly 120 includes a second rod 120B, which is long and thin, existing between the two terminal legs 120L. Together, the second bar 120B and the two terminal legs 120L form a U-shape in the illustrated embodiment. Other shapes are envisioned, such as T, V and C-shapes. Each of the terminal legs 120L extends outward from the end of the second rod 120B toward the side B of the power module, passes through the side surface of the housing 112 at an angle between 75 degrees and 105 degrees, and ) is shaped to rotate upward toward the top of the 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. The exposed distal ends of terminal legs 120L provide MID-terminal contacts 120C to MID-terminal assembly 120 .

A second notable difference between power module 10 and power module 100 described above is that MID-terminal contacts 120C are placed on the housing (as done on power module 10 (eg, FIG. 3 )). 112) does not fold back over the bottom surface. Like pin assemblies 120', 124, 126, MID-terminal contacts 120C are substantially perpendicular to the plane in which housing 112 resides. The terminal leg 120L substantially forms an L-shape, and the vertical portion of the terminal leg 120L forms the MID-terminal contact 120C. Terminal legs 120L extend from the second bar 120B. The lower portions of the second bar 120B of the MID-terminal assembly 120 are directly attached to the source contacts of the transistors Q1 (power devices 116).

The MID-terminal assembly 120 in this embodiment includes a plurality of (two) integrally formed jumpers extending from the second bar 120B toward the first bar 118B of the V-terminal assembly 118. s 120J are also included. The distal ends of jumpers 20J are attached directly to second trace 136 on the top surface of substrate 114, as described above. Jumper 120J may be replaced with a single bar. Additionally, the number of jumpers 120J may vary from embodiment to embodiment. For example, three jumpers 120J have been provided on the power module 10 as described above. In certain embodiments, there will be one jumper 120J per power device 116 connected to MID-terminal assembly 120 .

In this embodiment, terminal legs and contacts 120L, 120C of MID-terminal assembly 120 allow welding to a thicker outer bus bar using conventional and more readily available side welding operations. Since MID-terminal assembly 120 carries the AC output of power module 100, thicker bus bars may be preferred or required for higher current applications.

For each of the opposite V+ terminal assemblies 122 , one end is attached directly to the first trace 134 on top of the substrate 114 . From the substrate 114, each opposite terminal 122 extends outward toward sides C and D of the power module 100, passes through each side of the housing 112, and the top of the housing 112. and then rotated inward over a portion of the top of the housing 112 . As such, the distal portion of each of the V+ terminal assemblies 122 is bent back over its middle portion. The exposed distal ends of opposite terminals 122 provide terminal contacts 122C for V+ terminal assemblies 122 .

Referring specifically to FIGS. 29 and 30 , groups of nested signal pin assemblies 118', 120', 124, 126 and 128, 130 are provided on opposite sides of the housing 112. Pin assemblies 126 and 130 are T-shaped and include pin legs 126L and 130L extending from central portions of respective pin rods 126B and 130B and respective pin rods 126 and 130, respectively. each includes Pin legs 126L and 130L extend laterally outward from their respective pin bars 130B before rotating approximately 90 degrees toward the bottom side of power module 100 .

Pin assemblies 124 and 128 are generally L-shaped and include pin legs 124L, 128L extending from the distal portions of each pin rod 124B, 128B and each pin rod 126, 130. ), respectively. pin legs 126L, 130L extend laterally outward from respective pin rods 126B, 130B and rotate toward pin legs 126L, 130L of pin assemblies 126, 130; Rotate approximately 90 degrees outward and then rotate approximately 90 degrees towards the bottom side of the power module 100 . 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.

Pin assemblies 118' and 120', which are essentially additional pin legs, are integral extensions of terminal legs 118L and 120L of V-terminal assembly 118 and MID-terminal assembly 120, respectively. Pin assembly 118' extends laterally from bus bar 118B and/or terminal leg 118L prior to approximately 90 degree rotation toward the bottom side of power module 100, and ultimately pin assembly 130. ) continues next to the pin leg 130L. The pin assembly 120' rotates between 75 and 105 degrees towards the bottom side of the power module 100 and ultimately extends next to the pin leg 126L of the pin assembly 126 before it is connected to the bus bar 120B and /or continues laterally from the terminal leg 120L. An end portion of pin leg 130L of pin assembly 130 is between the end portions of pin assembly 118' and pin leg 128L of 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.

By having the pin assembly 118' extend directly from the V- terminal assembly 118, the pin assembly 118' is connected to the pin assembly 118, corresponding to the V- and low side source Kelvin signal voltages K2. ') and the pin assembly 130L can be used to sense currents and overcurrent events. Similarly, by having the pin assembly 120' extend directly from the MID-terminal assembly 120, the pin assembly 120' corresponds to the V- and high side source Kelvin signal voltages K1. Analyzing the voltage difference between 120' and pin assembly 126 can be used to sense current and overcurrent events. Schematically, pin assembly 118' and pin assembly 120' correspond to signals S2 and S1 respectively in FIG. 1B. 1A and 1B are essentially the same, where the S1 and S2 terminals correspond to the pin assemblies 120' and 118' for the present embodiment. Bond wires 132 electrically connect power devices 116 to pin rods 124B, 126B, 128B, 130B of pin assemblies 124, 126, 128, 130.

Referring specifically to FIGS. 27, 28, and 32 , the internal workings of the power module 100 are encapsulated by a protective plastic or epoxy housing 112 via transfer molding, compression molding, injection molding, or a similar process. Several notable features of housing 112 are highlighted and discussed below. As shown in FIGS. 28 and 32 , the backside metal of the power substrate 114 is exposed on the underside of the power module 100 to provide a thermal pad 156 . Thermal pad 156 is used as a thermal contact surface to remove heat from power module 100 . Thermal pad 156 may be sintered, soldered, epoxidized, or similarly attached to a heat sink or cooling plate (not shown) to further aid in the removal of waste heat from power module 100 .

Features in housing 112 may vary based on manufacturing method. The illustrated embodiment is representative of the structural properties of transfer molding. As illustrated in FIG. 27 , four retaining pin marks 157 are shown, but may be more or fewer depending on the overall size of the power module 100 . Securing pins (not shown) press directly against the power substrate during the transfer molding process to limit the amount of plastic bleed or flash on the exposed portion of the thermal pad 156 . This ensures that the thermal surface is free of debris and that the thermal surface can serve to efficiently remove heat. There are also ejector marks 158 around the perimeter of the housing 112 . Ejector marks 158 are small recesses created by ejector pins (not shown) used to remove power module 100 from mold (not shown) while still hot. The specific locations of these features and associated geometries will vary depending on the specific product size and implementation.

Clearance and creepage can be important aspects for high voltage products. Between conductors of different voltage potentials, clearance is the shortest direct path in air between the conductors. Creepage is the shortest direct path along a surface between conductors. Meeting safety standards is a challenge, often at odds with manufacturing methods (pores, 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 reach the right balance.

In certain embodiments, clearance distances are sufficient and within standards. Creepage extenders 60, such as those illustrated in FIGS. 14A and 14B for the power module 10 described above, may be used to increase the creepage distance and correspondingly increase the maximum allowable voltage. . Creepage extenders 60 are grooves, ripples, or other surface enhancements that extend the surface distance between conductors of different voltage potentials.

As described above, there are two categories of electrical loops in a power module: power loops and signal loops. The power loop is a high voltage, high current path through the transistors Q1, Q2 to deliver power to the load through the drain (or collector) and source (or emitter) of the transistors Q1, Q2, the load is typically the MID-terminal It is connected to the assembly 120. The signal loop is a low voltage, low current path through gates G1, G2 (or bases) and sources S (or emitters) of transistors Q1, Q2. The gate-source (or base-emitter) signal path activates the transistors Q1 and Q2 to actually turn them on or off. As described in detail below, the signal loop may also involve the source-Kelvin connections K1, K2 of transistors Q1, Q2.

The power loop continues substantially between V+ terminal assembly 122 and V- terminal assembly 118 . V+ terminal assembly 122 and V- terminal assembly 118 are typically connected across a DC power source, such as a battery, in parallel with a large capacitance.

Opposite V+ terminal assemblies 122 are directly attached to opposite ends of first trace 134 on substrate 114 . Power flows into power module 100 through legs 122C and contacts 122L of two V+ terminal assemblies 122 . As such, power flows through the terminal assemblies 122 onto the opposite ends of the first trace 134 on the substrate 114 and over the drain contacts of the transistors Q1. The drain contacts of transistors Q1 are at the bottoms of transistors Q1 and are also directly attached to second trace 136 . Transistors Q1 are 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 away from each other and the two V+ terminal assemblies are attached to the first trace 134. Equally spaced from the attachment points to (122).

Power then flows through transistors Q1 from the drains of transistors Q1 to the sources of transistors Q1. The sources of the transistors Q1 are attached to the lower side of the second bar 120B of the mid terminal assembly 20 at embossments E. The mid-terminal jumpers 120J of the mid-terminal assembly 120 connect the second rod 120B of the mid-terminal assembly 120 to the second trace 136 on the substrate 114 . The drains of transistors Q2 are directly attached to second trace 136 and equally spaced from each other. From the drains of transistors Q2, power flows through transistors Q2 to the sources of transistors Q2. The sources of transistors Q2 are directly connected to the bottom side of first rod 118B of V-terminal assembly 118 at embossments E. As such, power flows along first rod 118B and through opposing legs 118L to contacts 118C of V-terminal assembly 118 .

In particular, referring to FIGS. 29 and 30 , a plurality of embossings E may be provided on each of the first bar 118B of the V-terminal assembly and the second bar 120B of the MID-terminal assembly. Embossings E are provided over each of the power devices 116 and serve to extend portions of the first rod 118B and the second rod 120B downward towards the tops of the power devices. As such, the remaining non-embossed portions of first rod 118B and second rod 120B have more space between the top of substrate 114 and the bottom of first rod 118B and second rod 120B. allow The additional space aids in the manufacture of housing 112 by reducing the amount of pressure required to force the molding compound used to form housing 112 to flow into and fill these areas.

The first rod 118B and the second rod 120B also have recessed regions corresponding to fixed positions on the substrate 114 . As noted in the previous embodiment, stationary pins (not shown) are used in a transfer molding process, where they are generally some or all of the components of power module 100 while housing 112 is being formed. Press directly onto the substrate 114 to hold it in place.

Using symmetrical V+ terminal assemblies 122 and symmetrical V- terminal assembly 118, current sharing between devices is balanced, smaller external contacts can be used, which helps with lead frame panelization, and power By shortening the entire current path in the loop, the inductance is greatly reduced. As described further below, contacts 118C, 120C, 122C of V- terminal assembly 118, MID-terminal assembly 120, and V+ terminal assemblies 122 may be laser welded, solder , ultrasonic welds, mechanical bonds (clamps, springs, etc.), conductive adhesives, or any other conductive bond.

Current must flow through a closed circuit. Thus, the stray inductance of the package itself is not the only factor contributing to the overall loop inductance. Any capacitance of the power supply and inductance of the entire loop, including capacitors provided across the power supply, external bussing and wiring, and the power module 100 itself should be considered. As such, not only should the internal layout of power module 100 be low-inductance, but also the locations of V- terminal assembly 118, MID-terminal assembly 120, and V+ terminal assemblies 122 are low-inductance laminates. A busing or similar interconnection method of connecting power module 100 to a DC power source should also be allowed.

In this embodiment, the signal loops or gate and sources connections, for each transistor Q1, Q2 location, also benefit from a low impedance that minimizes the voltage stress on the gates of transistors Q1, Q2 during switching. receive Additionally, the power loops and signal loops are completely independent of each other, enabling low switching losses at high speed and with well-controlled dynamics.

The inner signal loop for this embodiment is similar to that illustrated in FIG. 11 . The signal loop for transistor Q1 flows onto and through G1 pin assembly 124 and then through bond wire 132 to the gate contact of transistor Q1, where the signal is presented to transistor Q1. A signal loop flows from transistor Q1 through the source contact of transistor Q1. From the source contact, the signal loop flows through another bond wire 132 directly to and through the K1 pin assembly 126 .

Similarly, the signal loop for transistors Q2 flows onto and through G2 pin assembly 128 and then through bond wire 132 to the gate contact of transistors Q2, and the signal is presented to transistors Q2. A signal loop flows from transistor Q2 through the source contact of transistor Q2. From the source contact, the signal loop flows through another bond wire 132 directly to and through the K2 pin assembly 130 . As shown, this is a true source-Kelvin implementation in which the power and signal loops are completely independent.

To minimize the length of the power loop, some or all of the edge power contacts, such as those for the V- and MID-terminal assemblies 118, 120, are coupled with the pin assemblies 124, 126, 128, 130. Similarly, compared to the signal contacts, it can be inserted from the edge of the housing 112. The signal contacts provided by the pin assemblies 124, 126, 128, 130 require more space to better accommodate the bond wires 132 from the devices; Accordingly, their housing sections extend outwardly from the edge of the entire housing 112 . This contour feature allows inductance optimization for each of the independent power and signal loops.

As noted above, terminal and pin assemblies 118-130 are formed from lead frame 144 and combine the functionality of providing high current internal interconnections, bond wire locations, and external terminal contact surfaces. Parts or components of lead frame 144 are attached to both substrate 114 as well as top source pads of transistors Q1 and Q2. Lead frame 144 may be attached to various components in several ways, including soldering, sintering, conductive epoxy, laser welding, ultrasonic welding, and the like. Surface enhancement features, such as holes, slots, feathered edges, '? Also referred to as 'solder or epoxy catches', as shown in FIG. 18, it can be used to reinforce the strength of a bond.

A strip on lead frame 144 that is directly attached to the top surface source pads may have several distinguishing features. Depending on the specific layout of the device being packaged, there may be a variety of solder catch implementations. Additionally, ripples (not shown) between devices for thermal expansion stress relief and enhanced molding flow may be included. Various bends of the lead frame 144 may be used as an additional means of stress relief.

Lead frame 144 may be fabricated from sheet metal in an etching or stamping process. One example of this is presented in FIGS. 33A and 33B. The contacts and inner features are joined to the outer frame by narrow tabs. To streamline processing in panels or magazines, much of the sheet metal starts out flat. Only internal bends are formed. Due to the multiple heating processes required by the assembly during manufacturing production, thermal expansion slots are added to break large copper areas. These limit expansion and warping of the assembly.

A lead frame 144 is attached to the power devices 116 and the substrate 114, wire bonded, then shaped and then trimmed away from the outer frame at the locations of the joining tabs. The folds of the outer contacts are formed by folding, often with procedural steps and optional trimming.

For automated mass production, these lead frames 144 are often patterned into an array. These arrays are handled on multiple machines, often loaded from magazines or racks. Holes on the top and bottom edges are used for fixturing, positioning, keying, and handling. An exemplary lead frame array 164 with four lead frames 144 is shown in FIG. 34 . The specific features of lead frames 144 and lead frame array 164 will vary depending on product configuration, product size variations, and types of manufacturing equipment.

35 and 36 are bottom and top isometric views of a wider variant of power module 100 . As indicated above, wider variants support the inclusion of more power devices 116 for the low and high-side transistors, which generally correspond to higher power handling capabilities for the power module 100. do.

The power module 10 and power module 100 described above have many identical elements as well as several unique elements. Each of these elements may be connected in any combination. For example, embossings E and unique pin assemblies 118', 120', 124, 126, 128, 130 may be incorporated into power module 10.

Silicon carbide (SiC) power devices offer high-level performance advantages, including high voltage shutdown, low on-resistance, high current, fast switching, low switching losses, high junction temperatures, and high thermal conductivity. Ultimately, these properties result in a notable increase in potential power density, which is the power processed per area or volume.

However, achieving this potential requires addressing significant challenges at the package and system level. Higher voltages, currents, and switching speeds result in significantly higher physical stress applied on smaller and more constrained areas. In order to fully exploit what SiC technology has to offer, one or more of the following challenges are addressed:

• Provide common circuit topologies both in the package (internal layout) and without the package (interconnect);

• removes waste heat from conduction and switching losses from devices;

· provides effective electrical isolation between high voltage potentials;

· Provides low-power loop inductance for minimal high-voltage overshoot during high-speed switching;

• Achieve low signal loop inductance for minimal gate voltage overshoot and oscillations;

• Optimize internal layout for parallelization of power devices to achieve dynamic and steady state current sharing;

· Offers low power loop resistance for high current carrying without overheating;

· provides an external terminal arrangement which is well suited for parallelization of modules and which features an easy arrangement into circuit topologies;

• Provide a balanced arrangement of power devices.

The internal layout, or physical arrangement of package components, significantly affects each of these factors. As the number of devices inside a package increases, it becomes increasingly difficult to realize an optimal layout. Parallelization is a common technique for SiC devices to increase the current capability of the package. The more devices in parallel, the progressively more difficult to balance the tradeoffs between thermal spread, power loop inductance, signal loop inductance, and package size. Forming the half-bridge topology introduces additional layout challenges as important parameters such as power loop inductance and equal heat transfer between switch locations become more design challenges.

Besides performance, cost must be kept low to appeal to a wide range of markets and applications. Some techniques that can help reduce costs include:

• limit the use of individual components by providing multiple functions in the same component;

· Optimize the functionality and performance of each component through design;

• limit the requirements of secondary or finishing operations;

• use conventional or well-established manufacturing methods known for their high yield;

• use batch or continuous processing using panels, strips, arrays, magazines, etc. where possible;

• Optimize package size and shape based on methods of manufacturing sub-components, such as sizing parts fabricated on strips or panels to maximize utilization of raw materials.

Ultimately, the combination of internal scalability and external modularity results in a highly adaptable core layout that can adapt to a wide range of system requirements.

This disclosure relates to, but is not limited to:

· Highly optimized half-bridge package design for next-generation SiC products;

• Scalable layouts in which products can be implemented by stretching or widening the package to allow more SiC area (via larger devices or more in parallel);

· A modular approach to external terminal locations for easily parallelizing multiple packages or arranging them as common circuit topologies;

· Ultra-low inductance, balanced power loop layout;

· Low inductance, balanced signal loop layout;

• True Kelvin implementation for signal loops;

· Left or right signal pin compatibility;

· Low-cost through minimization of the number of unique parts used;

· Low-cost through minimizing the area of the power board;

· Low-cost through lead frame array processing;

· High manufacturability using well-adopted lead frame array processing and transfer molding;

· Molded voltage creepage extenders on the top and bottom sides of the package; and

· Direct power attachment of the top side of the device to the lead frame.

The concepts presented 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 (28)

As a power module,
a substrate having a top surface with a first trace and a second trace;
a first plurality of vertical power devices and a second plurality of vertical power devices electrically connected to form part of a power circuit;
a first elongated rod, at least two first terminal contacts, and at least two first terminal legs each extending between different points of the first elongated rod and the at least two first terminal contacts; a first terminal assembly to;
a second elongate rod, at least two second terminal contacts, and at least two second terminal legs each extending between different points of the second elongate rod and the at least two second terminal contacts; a second terminal assembly; and
a housing comprising four sides between a top surface and a bottom surface, the housing encapsulating at least a portion of the first terminal assembly and the second terminal assembly;
First and second terminal legs of the at least two first terminal legs extend out of the first and second sides of the housing, and the at least two first terminal contacts extend over a bottom surface of the housing and thereby folded to be parallel;
each of the at least two second terminal legs extends and rotates out of the third side of the housing, the at least two second terminal contacts form an angle between 75 degrees and 105 degrees with the bottom surface of the housing; , the third side is between the first side and the second side of the housing. According to claim 1,
the first plurality of vertical power devices are electrically and mechanically directly connected between the first trace and the lower end of the first elongated bar of the first terminal assembly;
A second plurality of vertical power devices are electrically and mechanically directly connected between the second trace and the lower end of the second elongated rod of the second terminal assembly. According to claim 2,
a plurality of first embossments are provided in the first elongate rod and biased towards the substrate;
a plurality of second embossments are provided in the second elongate rod and biased toward the substrate;
each of said first plurality of vertical power devices electrically and mechanically directly connected between said first trace and a lower end of one of said plurality of first embossings in said first elongated rod of said first terminal assembly; ;
Each of the second plurality of vertical power devices is electrically and mechanically connected directly between the second trace and a lower end of one of the plurality of second embossings in the second elongated rod of the second terminal assembly. power module. 4. The apparatus of claim 3 further comprising a third terminal assembly and a fourth terminal assembly electrically and mechanically coupled to the second trace proximate opposite sides of the substrate;
the third terminal assembly includes a third terminal leg extending out of the first side of the housing and a third terminal contact extending over and parallel to the bottom surface of the housing;
wherein the fourth terminal assembly includes a fourth terminal leg extending out of the second side of the housing and a fourth terminal contact extending over and parallel to the bottom surface of the housing. 2. The apparatus of claim 1 further comprising a third terminal assembly and a fourth terminal assembly electrically and mechanically coupled to the second trace proximate opposite sides of the substrate;
the third terminal assembly includes a third terminal leg extending out of the first side of the housing and a third terminal contact extending over and parallel to the bottom surface of the housing;
wherein the fourth terminal assembly includes a fourth terminal leg extending out of the second side of the housing and a fourth terminal contact extending over and parallel to the bottom surface of the housing. The method of claim 1, further comprising:
A first pin assembly comprising a first pin rod and at least one first pin leg, wherein the at least one first pin leg extends from the first pin rod and out of the fourth side of the housing and then to the housing rotates at an angle of between 75 and 105 degrees with the bottom surface of the housing, the fourth side opposite the third side of the housing;
a second pin assembly comprising 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 out of the fourth side of the housing; rotated at an angle of between 75 degrees and 105 degrees with the bottom surface of the housing. 7. The apparatus of claim 6, wherein the first terminal assembly further comprises a third pin leg extending out of the fourth side of the housing and then rotating at an angle of between 75 and 105 degrees with the bottom surface of the housing. Power module containing. According to claim 7,
the first pin rod is between the first elongated rod and the second pin rod of the first terminal assembly;
and the at least one second pin bridge is between the at least one first pin bridge and the third pin bridge. The method of claim 1, further comprising:
A first pin assembly comprising a first pin rod and at least one first pin leg, wherein the at least one first pin leg extends from the first pin rod and out of the third side of the housing and then: rotated at an angle of between 75 and 105 degrees with the bottom surface of the housing; and
a second pin assembly comprising 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 out of the third side of the housing and then: rotated with the bottom surface of the housing at an angle of between 75 and 105 degrees, wherein the at least one first pin leg and the at least one second pin leg are interposed between the at least two second terminal contacts. power module. 10. The apparatus of claim 9, wherein the second terminal assembly further comprises a third pin leg extending out of the third side of the housing and then rotating at an angle of between 75 and 105 degrees with the bottom surface of the housing. Power module containing. According to claim 10,
the first pin rod is between the second elongated rod and the second pin rod of the second terminal assembly;
and the at least one second pin bridge is between the at least one first pin bridge and the third pin bridge. The method of claim 1, further comprising:
A first pin assembly comprising a first pin rod and at least one first pin leg, wherein the at least one first pin leg extends from the first pin rod and out of the fourth side of the housing and then to the housing rotates at an angle of between 75 and 105 degrees with the bottom surface of the housing, the fourth side opposite the third side of the housing;
a second pin assembly comprising 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 out of the fourth side of the housing; rotated at an angle of between 75 and 105 degrees with the bottom surface of the housing;
a third pin assembly comprising a third pin rod and at least one third pin leg, wherein the at least one third pin leg extends from the third pin rod and out of the third side of the housing and then: rotated at an angle of between 75 and 105 degrees with the bottom surface of the housing;
a fourth pin assembly comprising 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 out of the third side of the housing and then: rotated with the bottom surface of the housing at an angle of between 75 and 105 degrees, wherein the at least one third pin leg and the at least one fourth pin leg are interposed between the at least two second terminal contacts. power module. According to claim 12,
the first terminal assembly further comprises a fifth pin leg extending out of the fourth side of the housing and then rotating at an angle of between 75 and 105 degrees with the bottom surface of the housing;
wherein the second terminal assembly further includes a sixth pin leg extending out of the third side of the housing and then rotating at an angle of between 75 and 105 degrees with the bottom surface of the housing. According to claim 1,
the power circuit includes a power loop and at least one signal loop;
The power loop continues through the first plurality of vertical power devices and the second plurality of vertical power devices. 15. The power module of claim 14, wherein the power loop is independent of the at least one signal loop. 16. The power module of claim 15, wherein the at least one signal loop provides at least one control signal for the first plurality of vertical power devices or the second plurality of vertical power devices. 15. The power module of claim 14, wherein the power loop does not continue through any bond wires of the power module. The power module of 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 an H (half)-bridge circuit. 2. The method of claim 1, wherein the second terminal assembly further comprises a plurality of jumpers extending from the first elongate rod to the first trace, wherein the plurality of jumpers are electrically and mechanically connected to the first trace. power module to be connected. As a power module,
a substrate having a top surface with a first trace and a second trace;
a first plurality of vertical power devices and a second plurality of vertical power devices electrically connected to form part of a power circuit;
a first elongated rod, at least two first terminal contacts, and at least two first terminal legs each extending between different points of the first elongated rod and the at least two first terminal contacts; a first terminal assembly comprising a plurality of first embossments provided in the first elongate rod and biased toward the substrate; and
a second elongate rod, at least two second terminal contacts, and at least two second terminal legs each extending between different points of the second elongate rod and the at least two second terminal contacts; a second terminal assembly comprising a plurality of second embossments provided in the second elongate rod and biased toward the substrate;
each of said first plurality of vertical power devices electrically and mechanically directly connected between said first trace and a lower end of one of said plurality of first embossings in said first elongated rod of said first terminal assembly; ;
Each of the second plurality of vertical power devices is electrically and mechanically connected directly between the second trace and a lower end of one of the plurality of second embossings in the second elongated rod of the second terminal assembly. power module. According to claim 20,
the first plurality of vertical power devices are electrically and mechanically directly connected between the first trace and the lower end of the first elongated bar of the first terminal assembly;
A second plurality of vertical power devices are electrically and mechanically directly connected between the second trace and the lower end of the second elongated rod of the second terminal assembly. 22. The apparatus of claim 21 further comprising a third terminal assembly and a fourth terminal assembly electrically and mechanically coupled to the second trace proximate opposite sides of the substrate;
the third terminal assembly includes a third terminal leg extending out of the first side of the housing of the power module and a third terminal contact extending over and parallel to a bottom surface of the housing;
wherein the fourth terminal assembly includes a fourth terminal leg extending out of the second side of the housing and a fourth terminal contact extending over and parallel to a top surface of the housing. 21. The method of claim 20, further comprising:
A first pin assembly comprising a first pin rod and at least one first pin leg, the at least one first pin leg extending from the first pin rod and out of the fourth side of the housing of the power module and: rotates at an angle between 75 and 105 degrees with the bottom surface of the housing, the fourth side opposite the third side of the housing; and
a second pin assembly comprising 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 out of the fourth side of the housing; rotated at an angle of between 75 degrees and 105 degrees with the bottom surface of the housing. 24. The apparatus of claim 23, wherein the first terminal assembly further comprises a third pin leg extending out of the fourth side of the housing and then rotating at an angle of between 75 and 105 degrees with the bottom surface of the housing. Power module containing. According to claim 24,
the first pin rod is between the first elongated rod and the second pin rod of the first terminal assembly;
and the at least one second pin bridge is between the at least one first pin bridge and the third pin bridge. According to claim 20,
the power circuit includes a power loop and at least one signal loop;
the power loop continues 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;
wherein the at least one signal loop provides at least one control signal for the first plurality of vertical power devices or the second plurality of vertical power devices. 27. The power module of claim 26, wherein the power loop does not continue through any bond wires of the power module. 21. The power module of claim 20, wherein the substrate, the first plurality of vertical power devices, and the second plurality of vertical power devices comprise silicon carbide.

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