Power module and manufacturing method thereof

Abstract

There is provided a power module, the power module comprising: a substrate; one or more semiconductor bare chips mounted to the substrate; a first external power connection structure electrically connected to a first power terminal of at least one of the one or more semiconductor die; an encapsulation material at least partially encapsulating the first external power connection structure, where a portion of the first external power connection structure and at least a portion of an outer surface of the substrate are exposed from the encapsulation material; and a heat sink mounted to the first external power connection structure.

Description

Technical Field

[0001] The present disclosure relates to a power module and a power module assembly, and in particular to heat dissipation of a power module. Background Art

[0002] Many different applications, such as automotive and industrial applications, use power modules that include multiple power devices in a single package or housing. Power modules can include power conversion circuits such as single-phase and multi-phase half-wave rectifiers, single-phase and multi-phase full-wave rectifiers, voltage regulators, inverters, etc. High-performance power modules are designed to minimize power losses and can improve the energy efficiency of power systems. Power modules can be part of energy-saving solutions to reduce or prevent anthropogenic greenhouse gas emissions. For example, hybrid electric vehicles (HEV) or electric vehicles (EV) use power modules to perform power conversion, inversion, switching, etc. in an energy-efficient manner.

[0003] The maximum output current of a high-performance power module is usually limited by the external power terminals. The external power terminals are usually made of conductive material, such as copper, and the thermal expansion coefficient of the external power terminals is different from the material encapsulating the semiconductor chip and / or forming the power module housing. Therefore, the protrusion of the external power terminals through the encapsulation material should be kept to a minimum to avoid the risk of stress / cracking of the encapsulation material, thereby generating electrical isolation failure. On the other hand, the narrower the external contacts at the protruding parts of the encapsulation housing, the hotter they will become during operation when a large amount of current passes through these narrow parts.

[0004] The present disclosure provides a solution to the above-mentioned problems. Summary of the invention

[0005] A power module is disclosed, comprising: a substrate; one or more semiconductor bare chips mounted to the substrate; a first external power connection structure electrically connected to a first power terminal of at least one of the one or more semiconductor bare chips; an encapsulation material at least partially encapsulating the first external power connection structure, wherein a portion of the first external power connection structure and at least a portion of an outer surface of the substrate are exposed from the encapsulation material; and a heat sink mounted to the first external power connection structure.

[0006] A system is disclosed, comprising: a cooler, a power module as described above, wherein the substrate is mounted to a first surface of the cooler, and the heat sink is an extension of the cooler extending beyond an encapsulation material of the power module.

[0007] A power module is disclosed, comprising: a substrate; one or more semiconductor bare chips mounted to the substrate; a first external power connection structure electrically connected to a first power terminal of at least one of the one or more semiconductor bare chips; and an encapsulation material at least partially encapsulating the first external power connection structure, wherein an outer end portion of the first external power connection structure and at least a portion of an outer surface of the substrate are exposed from the encapsulation material, wherein a portion of the outer end portion of the first external power connection structure is bent to achieve coplanarity with the outer surface of the substrate exposed from the encapsulation material.

[0008] Those skilled in the art will recognize additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The present disclosure is illustrated in the accompanying drawings by way of example and not limitation, wherein the same reference numerals represent similar or identical elements. The elements in the accompanying drawings are not necessarily drawn to scale relative to each other. The features of the various illustrated examples may be combined unless mutually exclusive.

[0010] Figure 1 A cross-sectional view of a power module is shown with a heat sink mounted on its external power connection structure.

[0011] Figure 2 A power module is shown with a solid metal block mounted on the upper side of its external power connection structures.

[0012] Figure 3 A power module is shown with a finned cooling body mounted on the upper side of its external power connection structure.

[0013] Figure 4 A power module is shown having thermally conductive bars on its underside connecting external power terminals.

[0014] Figure 5 A power module is shown having a thermally conductive strip on the upper side of the power module, which connects the external power terminals on their upper bent-over sections.

[0015] Figure 6 A perspective view of a power module and a cooler with the power module mounted thereon is shown, wherein thermally conductive bars connecting external power terminals on the underside of the power module are also mounted on the cooler.

[0016] Figure 7 A power module is shown having a connection bar on the upper side of the power module, which connects external power terminals on an upper bent portion of an external power connection structure, wherein the external power terminals are connected to the connection bar on different sides of the connection bar.

[0017] Figure 8Shows the connection to the connecting strip on different sides of the connecting strip. Figure 7 Top view of the external power terminals in the .

[0018] Fig. 9 A power module and a cooler mounted with the power module are shown, wherein a portion of the cooler includes a raised portion that contacts an external power connection structure.

[0019] Fig.10 A power module and a cooler mounted with the power module are shown, wherein the external power connection structure is bent downward to contact the cooler on the same plane as the power module. DETAILED DESCRIPTION

[0020] The power module described herein may be a single-sided coolable or double-sided coolable power module, the power module comprising one or more semiconductor bare chips mounted on a substrate and encapsulated by an encapsulation material. In order to integrate the power module into a larger application, a first external power connection structure electrically connected to a first power terminal of at least one of the one or more semiconductor bare chips is provided. A heat sink mounted on the first external power connection structure may homogenize and reduce the peak temperature occurring during operation of the power module, especially at the external power connection structure, thereby achieving higher operating performance of the power module. The terms external power connection structure, external power terminal, external terminal, and external lead may be used interchangeably hereinafter.

[0021] See also Figure 1 , a first exemplary power module 100 is shown. The power module 100 includes a semiconductor bare chip 170 mounted on a substrate 130b. The upper substrate 130a is optional and can provide a double-sided coolable power module. In a double-sided coolable power module, the semiconductor bare chip 170 can be thermally connected and / or electrically connected to the upper substrate 130a directly or through a spacer 172. For both single-sided coolable and double-sided coolable variants, the external power connection structure 120 is mounted on the substrate 130b or can be integrally formed with the substrate 130b, and provides an electrical connection between the semiconductor bare chip 170 and the outside (e.g., a bus bar, a PCB, etc.). The encapsulation material 110 at least partially encapsulates the external power connection structure 120, wherein a portion of the external power connection structure 120 and at least a portion of the outer surface 131b of the substrate 130b are exposed from the encapsulation material 110. The insulating encapsulation material 110 between the exposed conductive material portions ensures the required creepage distance. Heat sinks 160a, 160b are mounted to the external power connection structure 120, either with heat sink 160b located below the external power connection structure as shown, or with heat sink 160a located above the external power connection structure, or both.

[0022] In order to electrically isolate the power module 100 from the outside, the substrates 130a and 130b may include an isolation layer 132a / b sandwiched between two conductive layers (e.g., metal layers), and the substrates are, for example, but not limited to, direct copper bonding (DCB) substrates, active metal brazing (AMB) substrates, or insulated metal substrates (IMS). The outer sides 131a and 131b of the substrates 130a and 130b may be mounted on coolers 150 and 152, respectively. The inner conductive layer may connect the semiconductor bare chip 170 to the external power connection structure 120 of the power module 100. According to the shapes of the heat sinks 160a and 160b and the shapes of the coolers 150 and 152, the heat sinks 160a and 160b may be selectively mounted on the sidewalls or surfaces of the coolers. In order to ensure electrical insulation, an insulating layer such as, but not limited to, a laminated foil or a thin ceramic layer ( Figure 1 The power module 100 has an additional external power connection structure 124, which can be positioned relative to the external power connection structure 120. Although not shown, the additional external power connection structure 124 can also be equipped with a heat sink, as shown in the external power connection structure 120.

[0023] The power module 100 may include a plurality of semiconductor bare chips 170 arranged as power conversion circuits, such as DC-DC converters, DC-AC converters, etc. These power conversion circuits may include a half-bridge circuit including a high-side switch connected in series with a low-side switch. The high-side and low-side switches may be provided by one or a group of discrete power transistor chips, MOSFETs, IGBTs, IGBTs, and diodes, etc.

[0024] Figure 2 An exemplary embodiment of a double-sided coolable power module 200 is shown, which includes all the features of the above-mentioned power module 100. The external power connection structure 120 of this exemplary embodiment includes three external power terminals 120, each of which includes a separate heat sink 260, 261, 262, and the heat sink 260, 261, 262 is installed on the upper side of the corresponding external power terminal 120. The external power terminal 120 can be as shown in FIG. Figure 2 As shown, they are bent so that they include a first portion 122a and a second portion 122b bent about 90°. Corresponding rectangular body heat sinks 260, 261, 262 can be installed on both sides of the L-shaped terminal. They can buffer the heat temporarily generated during operation, thereby reducing peak temperatures and avoiding critical hot spots. The heat sinks 260, 261, 262 can be solid metal blocks made of copper or aluminum, but are not limited thereto.

[0025] Alternatively, in Figure 3 In the illustrated power module 300 including all the features of the power module 100 , the heat sinks 360 , 361 , 362 may also provide a fin structure 365 protruding from a continuous portion 364 .

[0026] Reference Figure 4 , another exemplary power module 400a is shown. Similarly, the power module 400a includes all the features of the power module 100, and will only be described with reference to Figure 1 The external power connection structure 120 of this embodiment includes external power terminals 120a, 120b and 120c connected by a common heat sink 461. If the external power terminals 120a, 120b and 120c transmit direct current of different polarities, the heat sink needs to be electrically isolated from at least one of the external power terminals 120a, 120b and 120c. During operation, heat can be distributed between the external power terminals 120a, 120b and 120c to avoid hot spots. For example, if the internal power terminal 120b transmits a direct current of a first polarity, and the external power terminals 120a and 120c transmit current of a second polarity, the internal power terminal 120b may become hotter than the two external terminals, thereby forming a bottleneck in the current carrying capacity. The common heat sink 461 installed on the lower side of the external terminals 120a-c can make the heat more evenly distributed between the power terminals 120a-c, so that the overall current carrying capacity can be increased. If two or more external power terminals 120a, 120b, and 120c carry the same current phase, the heat sink 461 may provide an electrical connection between these power terminals in addition to a thermal connection.

[0027] Additionally or alternatively, the common heat sink 462 may also be connected to the upper curved portion 122b of the external power terminals 120a-c, such as Figure 5 The power module 400b is similar to Figure 4 power module 400a, and will only be used with Figure 4 . As exemplarily shown, the common heat sink 462 is formed by an insulating layer 466 connecting all three external power terminals. The insulating layer may include ceramics, laminates, etc. In order to increase the thermal conductivity of the common heat sink 462, there may be an additional layer 467 connected to the other side of the common heat sink, such as but not limited to a metal layer that generally has a higher thermal conductivity than the electrical insulation layer. Therefore, compared to a purely insulating connection, the heat transfer from one external power terminal to another external power terminal can be further increased.

[0028] Figure 6 Another embodiment of the present disclosure is shown, in which the power module assembly 500 includes three power modules, each power module is similar to Figure 4 and Figure 5 The power modules 400a and 400b shown in the figure. Compared with the power modules 400a and 400b, the external power connection structure can have a different length. As shown in the figure, the upwardly bent portion of the external power connection structure 122 can be connected to one side 567 of the common heat sink 562, wherein the external power connection structure 123 is longer or protrudes further outward from the encapsulation material 110 than the external power connection structure 122, so that the bent portion of the external power connection structure 123 can be connected to the other side of the common heat sink 562. Similarly, as shown in FIG. Figure 7 As shown, the common heat sink may consist only of electrically insulating material 466 to distribute heat between the different power terminals, but may also have additional conductive layers 567, 568 mounted on respective sides of insulating layer 466 and connected to one or more other power terminals to provide electrical connections between subsets of external power connection structures. Alternatively, only layer 567 or layer 568 may be used. Figure 7 In the illustrated embodiment, both layer 567 and layer 568 are used, each layer being used for a different polarity. When the heat sink 562 is used to connect the external terminals of multiple semiconductor power modules, since the multiple semiconductor power modules can be electrically connected in parallel, the additional electrical connections between the external power terminals can further facilitate the connection with external circuits (such as batteries, capacitors, etc.). Since there is a minimum distance between electrical connections of the same potential, the slight electrical imbalance that may exist within a semiconductor power module can be effectively reduced. Since the opposite currents (positive and negative) are kept in close proximity along the entire heat sink, the magnetic fields generated by the opposite currents almost completely cancel each other out. Thus, the inductance can be reduced.

[0029] Figure 8 Another embodiment of a power module assembly 600 is shown. The assembly is similar to Figure 4 The heat sink 661 includes an insulating layer 466 sandwiched between two metal layers 667, 668, as shown in FIG. Figure 6 and Figure 7 As described in detail. The heat sink 661 is in direct contact with the cooler 152, on which the heat sink 661 and the power module 600 are mounted. The lower side of the heat sink 661 and the lower side of the power module, such as the lower side of the exposed substrate 131b, are coplanar in this example. In other words, the heat sink 661 bridges the gap between the power terminal 120 and the cooler 152.

[0030] Alternatively, the cooler and / or external power leads may be Fig. 9 and 10 Adjust height / position as shown. Fig. 9 Shown with Figure 1 Similar power module 100 and cooler arrangement, and will only be used with Figure 1 The cooler 752 includes a step portion 753 that bridges the distance between the lower side of the power module 700 (e.g., the lower side of the exposed outer surface 131b of the substrate 130b framed by the encapsulation material 110) and the power terminal 120. In order to provide electrical isolation between the cooler 752 and the power terminal 120, an isolation structure needs to be provided between the two components. The isolation structure can be, but is not limited to, a laminated foil, a thermal interface material, a ceramic, etc., which are Fig. 9 Not shown.

[0031] In addition to partially raising the cooler, the power terminal 120 may also be bent downward 122c to align with the Fig.10 The underside of the power module 800 is shown to be coplanar so that the power module 800 and the underside of the power terminal 122c can be mounted to the planar cooler 152. Fig. 9 In the previous embodiments shown in , electrical isolation between the cooler and the power terminals needs to be provided between the two components, which can be implemented as but not limited to laminate foils, thermal interface materials, ceramics, etc.

[0032] More examples:

[0033] Example 1: A power module comprising a substrate; one or more semiconductor bare chips mounted to the substrate; a first external power connection structure electrically connected to a first power terminal of at least one of the one or more semiconductor bare chips; an encapsulating material at least partially encapsulating the first external power connection structure, wherein a portion of the first external power connection structure and at least a portion of an outer surface of the substrate are exposed from the encapsulating material; and a heat sink mounted to the first external power connection structure.

[0034] Example 2: The power module of Example 1, wherein the heat sink is adapted to be thermally connected to a cooler mountable to an outer surface of the substrate.

[0035] Example 3: The power module of Example 2, wherein the heat sink is electrically isolated from the first external power connection structure by an isolation layer between the heat sink and the cooler or between the external power connection structure and the heat sink.

[0036] Example 4: The power module according to any one of Examples 1 to 3, wherein the heat sink is a large metal block, preferably made of copper.

[0037] Example 5: The power module of Example 1 or 2, wherein the heat sink comprises a continuous portion along a portion of the first external power connection structure and a cooling structure protruding from the continuous portion.

[0038] Example 6: The power module according to Example 1 further includes a second external power connection structure, which is electrically connected to the second power terminal of at least one of the one or more semiconductor bare chips and is separated from the first external power connection structure; the encapsulation material at least partially encapsulates the second external power connection structure, wherein the outer end of the second external connection is exposed from the encapsulation material; and the heat sink thermally connects the exposed portions of the first and second external power connection structures.

[0039] Example 7: The power module of Example 6, wherein the first external power connection structure and the second external power connection structure are adapted to carry currents of different polarities during operation.

[0040] Example 8: The power module of Example 6 or 7, wherein a surface of the heat sink facing away from the first and second external power connection structures is coplanar with an outer surface of the substrate.

[0041] Example 9: The power module of any one of Examples 6 to 8, wherein the outer surface of the substrate and the heat sink are adapted to be mounted to a cooler.

[0042] Example 10: The power module according to any one of Examples 6 to 9, wherein the heat sink includes an isolation layer, preferably ceramic.

[0043] Example 11: The power module according to Example 10, wherein the isolation layer is sandwiched by two metal layers, and the first external power connection structure is mounted to a first metal layer of the two metal layers, and the second external power connection structure is mounted to a second metal layer of the two metal layers.

[0044] Example 12: A system comprising: a cooler, a power module according to Example 1, and wherein the substrate is mounted to a first surface of the cooler, and wherein the heat sink is an extension of the cooler extending beyond an encapsulation material of the power module.

[0045] Example 13: A system according to Example 12, wherein the cooler includes a stepped portion, and wherein the substrate is mounted to the cooler in a first plane and the end of the first external power connection structure is mounted to the cooler in a second plane different from the first plane.

[0046] Example 14: The system of Example 13, wherein the cooler has a planar surface, and wherein a portion of the outer end of the first external power connection structure is formed coplanar with the outer surface of the substrate and mounted to an extension of the cooler.

[0047] Example 15: A power module comprising a substrate; one or more semiconductor bare chips mounted to the substrate; a first external power connection structure electrically connected to a first power terminal of at least one of the one or more semiconductor bare chips; an encapsulating material at least partially encapsulating the first external power connection structure, wherein an outer end of the first external power connection structure and at least a portion of an outer surface of the substrate are exposed from the encapsulating material; wherein a portion of the outer end of the first external power connection structure is bent to form a coplanar shape with the outer surface of the substrate exposed from the encapsulating material.

[0048] Although specific examples have been illustrated and described herein, those skilled in the art will recognize that various alternatives and / or equivalent implementations may be substituted for the specific examples shown and described without departing from the scope of the invention. This application is intended to cover any modifications or variations of the specific examples discussed herein. Therefore, the present invention is limited only by the claims and their equivalents.

[0049] It should be noted that the description and the accompanying drawings illustrate only the principles of the proposed method and system. Those skilled in the art will be able to implement various arrangements that, although not explicitly described or shown herein, embody the principles of the present invention and are included in its spirit and scope. In addition, all examples and embodiments summarized in this document are primarily and explicitly used only for explanatory purposes to help the reader understand the principles of the proposed method and system. In addition, all statements of the principles, aspects and embodiments of the present invention and specific examples thereof are provided herein and are intended to cover their equivalents.

Claims

1. A power module (100, 200, 300, 400a, 400b, 500, 600), the power module comprising: Substrate (130a, 130b); One or more semiconductor bare chips (170) mounted to the substrate (130a, 130b); a first external power connection structure (120) electrically connected to a first power terminal of at least one of the one or more semiconductor die (170); an encapsulation material (110) at least partially encapsulating the first external power connection structure (120), wherein a portion (122) of the first external power connection structure and at least a portion of an outer surface (131a, 131b) of the substrate (130a, 130b) are exposed from the encapsulation material (110); A heat sink (160a, 160b, 260, 261, 262, 360, 361, 362, 461, 462) mounted to the first external power connection structure (120).

2. The power module according to claim 1, wherein: The heat sink (160a, 160b, 461, 462) is adapted to be thermally connected to a cooler (150, 152) that can be mounted to an outer surface (131a, 131b) of the substrate (130a, 130b).

3. The power module according to claim 2, wherein: The heat sink (160a, 160b, 461, 462) is electrically isolated from the first external power connection structure (120) by an isolation layer (466) located between the heat sink (160a, 160b, 461, 462) and the cooler (150, 152) or between the first external power connection structure (120) and the heat sink (160a, 160b, 461, 462).

4. The power module according to any one of claims 1 to 3, wherein: The heat sink (260, 261, 262) is a metal block, preferably made of copper.

5. The power module according to claim 1 or 2, wherein: The heat sink (360, 361, 362) includes a continuous portion (364) along a portion of the first external power connection structure (120) and a cooling structure (365) protruding from the continuous portion (364).

6. The power module (400a, 400b) according to claim 1, wherein: The power module further comprises a second external power connection structure (120b), the second external power connection structure being electrically connected to a second power terminal of at least one of the one or more bare semiconductor chips (170) and being separated from the first external power connection structure (120a); The encapsulating material (110) at least partially encapsulates a second external power connection structure (120b), wherein outer ends (122a, 122b) of the second external power connection structure (120b) are exposed from the encapsulating material (110); The heat sink (461, 462) is thermally connected to the exposed portions of the first external power connection structure (120a) and the second external power connection structure (120b).

7. The power module according to claim 6, wherein: The first external power connection structure (120a) and the second external power connection structure (120b) are adapted to carry currents of different polarities during operation.

8. The power module (400a) according to claim 6 or 7, wherein: The surface of the heat sink (461, 661) facing away from the first external power connection structure (120a) and the second external power connection structure (120b) is coplanar with the outer surface (131b) of the substrate (130b).

9. The power module (100, 600) according to any one of claims 6 to 8, wherein: The outer surface (131b) of the substrate (130b) and the heat sink (661) are suitable for mounting on a cooler (152, 752).

10. The power module (100, 600) according to any one of claims 6 to 9, wherein: The heat sink (461, 462, 661) comprises an insulating layer, preferably ceramic (466).

11. The power module (500) according to claim 10, wherein: The isolation layer (466) is sandwiched by two metal layers (567, 568), and the first external power connection structure (122) is installed on the first metal layer of the two metal layers (567), while the second external power connection structure (123) is installed on the second metal layer of the two metal layers (568).

12. A system (700, 800), comprising: Cooler (152, 752), The power module according to claim 1, wherein The substrate (130b) is mounted to a first surface of a cooler (152, 752), the heat sink being an extension of the cooler (152, 752) extending beyond an encapsulation material (110) of a power module.

13. The system according to claim 12, wherein: The cooler (752) includes a stepped portion (753), the substrate (130b) is mounted on the cooler (752) in a first plane, and the end of the first external power connection structure (120) is mounted on the cooler (752) in a second plane different from the first plane.

14. The system according to claim 12, wherein: The cooler (152) has a flat surface, and a portion (122c) of the outer end portion (122) of the first external power connection structure (120) is formed to be coplanar with the outer surface (131b) of the substrate (130b) and mounted on an extension portion of the heat sink.

15. A power module (100b), comprising: A substrate (130b); One or more semiconductor bare chips (170) mounted to the substrate (130b); a first external power connection structure (120) electrically connected to a first power terminal of at least one of the one or more semiconductor die; an encapsulation material (110) at least partially encapsulating the first external power connection structure (120), wherein an outer end (122) of the first external power connection structure (120) and at least a portion of an outer surface (131b) of the substrate (130b) are exposed from the encapsulation material (110); A portion (122c) of an outer end portion (122) of a first external power connection structure (120) is bent to be coplanar with an outer surface (131b) of the substrate (130b) exposed from the encapsulation material (110).

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