Power module with low stray inductance

Abstract

The utility model discloses a power module with low stray inductance, which comprises a substrate, the substrate is connected with a chip, a positive power terminal and a negative power terminal, and the negative power terminal and the positive power terminal are arranged in parallel. The projection of one of the negative power terminal and the positive power terminal on the substrate completely covers the projection of the other one on the substrate, and the negative power terminal and the positive power terminal are arranged in a mutually insulated manner. According to the scheme, the stray inductance in the power module can be reduced.

Description

Technical Field

[0001] The present application relates to the technical field of power modules, and particularly to a power module with low stray inductance. Background Art

[0002] A power module is an electronic device used to control the output of a rectifier and an inverter, and plays a role in controlling current and power supply. Due to various reasons such as the terminal structure, the arrangement of the substrate circuit, and the arrangement of components, stray inductance will be generated in the power structure. The stray inductance will cause voltage spikes between the collector and emitter of the power chip, thereby generating relatively high switching losses, affecting the working efficiency and current capacity of the power module, and even causing damage to the power module in severe cases.

[0003] Figure 1 Fig. shows an existing in-vehicle power module, whose internal main structure includes a copper-clad substrate, a chip, a positive power terminal, a negative power terminal, a phase power terminal, and a copper clip. This structure usually reduces the stray inductance of the power module to about 10 nH by symmetrically designing the surface circuit of the copper-clad substrate and rationally arranging components. However, due to the fact that the bonding position of the power terminal and the substrate is far from the chip, and the arrangement of the power terminals is asymmetric, more than half of the stray inductance is concentrated in the section from the power terminal and the bonding point to the chip. With the continuous increase in the switching speed of the power module chip and the continuous increase in the passing current, this traditional in-vehicle power module structure limits the further improvement of performance. Summary of the Utility Model

[0004] In order to solve the above problems, the present application provides a power module with low stray inductance.

[0005] A power module with low stray inductance provided by an embodiment of the present application includes a substrate, on which a chip, a positive power terminal, and a negative power terminal are connected. The negative power terminal and the positive power terminal are arranged in parallel, and the projection of one of the negative power terminal and the positive power terminal on the substrate completely covers the projection of the other on the substrate. The negative power terminal and the positive power terminal are insulated from each other.

[0006] In some embodiments, an insulating layer is provided between the negative power terminal and the positive power terminal.

[0007] In some embodiments, the insulating layer is simultaneously attached to the negative power terminal and the positive power terminal.

[0008] In some embodiments, the positive power terminal and the negative power terminal are respectively connected to the substrate through pads.

[0009] In some embodiments, the positive power terminal and the negative power terminal each include a connecting portion and a main body portion, the thickness of the connecting portion is less than that of the main body portion, and the positive power terminal and the negative power terminal are respectively connected to the corresponding spacer through their respective connecting portions.

[0010] In some embodiments, the chip includes an upper half-bridge chip and a lower half-bridge chip, the positive power terminal is connected to the positive electrode of the upper half-bridge chip, and the negative power terminal is connected to the negative electrode of the lower half-bridge chip;

[0011] A phase power terminal is further connected to the substrate, and the phase power terminal is connected to the negative electrode of the upper half-bridge chip and the positive electrode of the lower half-bridge chip.

[0012] In some embodiments, a plurality of the upper half-bridge chips and a plurality of the lower half-bridge chips are respectively provided. After the negative electrodes of the plurality of upper half-bridge chips are connected to each other through a first connecting member, they are connected to the phase power terminal; after the negative electrodes of the plurality of lower half-bridge chips are connected to each other through a second connecting member, they are connected to the negative power terminal.

[0013] In some embodiments, the connection point between the positive power terminal and the substrate is disposed close to the upper half-bridge chip; the connection point between the negative power terminal and the substrate is disposed close to the lower half-bridge chip.

[0014] In some embodiments, the widths of the positive power terminal and the negative power terminal are less than or equal to the width of the substrate.

[0015] In some embodiments, the positive power terminal and the negative power terminal are each a wide copper busbar.

[0016] In some embodiments, the substrate is a copper-clad substrate.

[0017] The technical solution of the present application has at least the following advantages:

[0018] 1. By providing a substrate, a chip, a positive power terminal, and a negative power terminal, and the negative power terminal and the positive power terminal are parallel to each other, and the projection of one of the negative power terminal and the positive power terminal on the substrate completely covers the projection of the other on the substrate. In the power device circulating current, since the negative power terminal and the positive power terminal are parallel to each other, the magnetic fields generated by the two are mutually coupled, thereby reducing the stray inductance of the negative power terminal and the positive power terminal segments;

[0019] 2. By providing an insulating layer between the positive power terminal and the negative power terminal, and the insulating layer is simultaneously attached to the negative power terminal and the positive power terminal, the distance between the positive power terminal and the negative power terminal can be minimized, further reducing the stray inductance;

[0020] 3. By setting the bonding points of both the positive power terminal and the negative power terminal to the substrate close to the chip, the stray inductance from the bonding point to the chip section can be reduced. Description of the Drawings

[0021] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] Figure 1 is a schematic diagram for embodying a power module in the prior art;

[0023] Figure 2 is a schematic diagram of a power module with low stray inductance provided by an exemplary embodiment of the present application;

[0024] Figure 3 is a top view of a power module with low stray inductance provided by an exemplary embodiment of the present application;

[0025] Figure 4 is a front view of a power module with low stray inductance provided by an exemplary embodiment of the present application;

[0026] Figure 5 is a top view for embodying the surface of the substrate provided by an exemplary embodiment of the present application.

[0027] Description of the Reference Numerals:

[0028] 1. Substrate; 11. First copper foil; 12. Second copper foil; 13. Third copper foil; 21. Upper half-bridge chip; 22. Lower half-bridge chip; 3. Positive power terminal; 4. Negative power terminal; 5. Phase power terminal; 6. Insulating layer; 7. Spacer; 7a. First spacer; 7b. Second spacer; 7c. Third spacer; 81. First connecting member; 82. Second connecting member. Detailed Embodiments

[0029] The following will clearly and completely describe the technical solutions in the present application in conjunction with the drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments in the present application belong to the scope of protection of the present application.

[0030] In the description of the present application, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present application. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0031] In the description of the present application, it should be noted that unless otherwise clearly specified and limited, the terms "mounted", "connected", "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can also be the communication inside two elements. It can be a wireless connection or a wired connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0032] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0033] An embodiment of the present application discloses a power module with low stray inductance. Referring to Figure 2 and Figure 3 , it includes a substrate 1, on which a chip, a positive power terminal 3, a negative power terminal 4, and a phase power terminal 5 are connected. In the embodiment of the present application, the substrate 1 is a copper-clad substrate, and the materials of the positive power terminal 3, the negative power terminal 4, and the phase power terminal 5 can be aluminum, silver, copper alloy, aluminum alloy, or copper, aluminum, etc. with a metal coating on the surface.

[0034] Among them, the negative power terminal 4 and the positive power terminal 3 are arranged in parallel, and the projection of one of the negative power terminal 4 and the positive power terminal 3 on the substrate 1 completely covers the projection of the other on the substrate 1. The widths of the positive power terminal 3 and the negative power terminal 4 can be the same or different. When the width of the negative power terminal 4 is less than that of the positive power terminal 3, the projection of the positive power terminal 3 on the substrate 1 completely covers the projection of the negative power terminal 4 on the substrate 1. In the power device circulating current, since the negative power terminal 4 and the positive power terminal 3 are parallel to each other, the magnetic fields generated by the two are mutually coupled, thereby reducing the stray inductance of the negative power terminal 4 and the positive power terminal 3 segments. At the same time, when the widths of the positive power terminal 3 and the negative power terminal 4 are the same, the effect of weakening the stray inductance is the best. Both the positive power terminal 3 and the negative power terminal 4 can adopt wide copper bars. On the premise that the width is less than or equal to the substrate width, the larger the widths of the positive power terminal 3 and the negative power terminal 4, the better.

[0035] The positive power terminal 3 and the negative power terminal 4 are insulated from each other. On the one hand, mutual insulation can be achieved by designing the distance between the positive power terminal 3 and the negative power terminal 4 to be greater than or equal to the insulation distance. In this case, the smaller the distance between the positive power terminal 3 and the negative power terminal 4, the better the effect of weakening the stray inductance. On the other hand, mutual insulation can also be achieved by arranging an insulating layer 6 between the negative power terminal 4 and the positive power terminal 3. The insulating layer 6 can be adhesively connected to one of the opposite sides of the positive power terminal 3 and the negative power terminal 4, or, Figure 2 as shown, it can be installed on the positive power terminal 3 in a plastic-coated manner. When the insulating layer 6 is arranged between the negative power terminal 4 and the positive power terminal 3, the insulating layer 6 can be attached to both the negative power terminal 4 and the positive power terminal 3 simultaneously to have the best effect of weakening the stray inductance.

[0036] The positive power terminal 3, the negative power terminal 4 and the phase power terminal 5 can be directly welded to the substrate 1, or, further, in order to reduce the difficulty of the assembly process, referring to Figure 4 , the positive power terminal 3, the negative power terminal 4 and the phase power terminal 5 can be respectively connected to the substrate 1 through the spacer blocks 7. Among them, the lower surface of the spacer blocks 7 can be fixedly connected to the front surface of the substrate 1 by welding, sintering and other methods. At the same time, when the laser welding process is adopted, compared with directly welding the positive power terminal 3, the negative power terminal 4 and the phase power terminal 5 on the substrate 1, the existence of the spacer blocks 7 can also reduce the difficulty of the laser welding process and prevent the laser welding energy from being too high to burn through the substrate 1 or too low to cause false soldering.

[0037] The spacer 7 includes a first spacer 7a, a second spacer 7b, and a third spacer 7c. The positive power terminal 3, the negative power terminal 4, and the phase power terminal 5 can be respectively connected to the upper surfaces of the first spacer 7a, the second spacer 7b, and the third spacer 7c in sequence by welding or sintering.

[0038] Furthermore, the positive power terminal 3, the negative power terminal 4, and the phase power terminal 5 respectively include a connecting portion and a main body portion, and the thickness of the connecting portion is less than that of the main body portion. The positive power terminal 3, the negative power terminal 4, and the phase power terminal 5 are respectively connected to the corresponding spacer 7 through their respective connecting portions. As Figure 3 shown, taking the positive power terminal 3 and the phase power terminal 5 as examples for illustration, the positive power terminal 3 includes a main body portion 32 and two connecting portions 31 located at both ends of the main body portion 32. The first spacer 7a can be connected to one of the connecting portions 31 by laser welding, and the other connecting portion 31 of the positive power terminal 3 can be connected to an external interface by laser welding. The phase power terminal 5 includes a main body portion 52 and two discrete connecting portions 51. Among them, the third spacer 7c can be connected to one of the connecting portions 51 by laser welding, and the other connecting portion 51 of the phase power terminal 5 can be connected to an external interface by laser welding. Since the thickness of the connecting portion is relatively thin, it is beneficial to implement the laser welding process. Since the thickness of the main body portion is relatively thick, it can also alleviate the heat generation phenomenon of the positive power terminal 3, the negative power terminal 4, and the phase power terminal 5 during current flow.

[0039] Furthermore, referring to Figure 5 , the front surface of the substrate 1 includes a first copper foil 11, a second copper foil 12, and a third copper foil 13 that are isolated from each other. The chip includes a plurality of upper half-bridge chips 21 surface-mounted on the first copper foil 11 and a plurality of lower half-bridge chips 22 surface-mounted on the second copper foil 12. The bottom end of the positive power terminal 3 is fixedly connected to the first copper foil 11 through the first spacer 7a, and then connected to the positive electrode of the upper half-bridge chip 21. The bottom end of the phase power terminal 5 is fixedly connected to the second copper foil 12 through the third spacer 7c, and then connected to the positive electrode of the lower half-bridge chip 22. The bottom end of the negative power terminal 4 is fixedly connected to the third copper foil 13 through the second spacer 7b.

[0040] The surface of the substrate 1 is also provided with a first connecting member 81 and a second connecting member 82. Among them, the first connecting member 81 and the second connecting member 82 can be made of such as Figure 5The copper clip shown can also be a similar structure or wire made of other conductive metals. Both the first connector 81 and the second connector 82 include a bus terminal and a number of branch terminals. The bus terminal of the first connector 81 is fixedly connected to the second copper foil 12, and the branch terminals are respectively connected to the negative electrodes of each upper half-bridge chip 21 one by one, so as to realize the connection between the phase pole power terminal 5 and the negative electrode of the upper half-bridge chip 21. The bus terminal of the second connector 82 is fixedly connected to the third copper foil 13, and the branch terminals are respectively connected to the negative electrodes of each lower half-bridge chip 22 one by one, so as to realize the connection between the negative power terminal 4 and the negative electrode of the lower half-bridge chip 22.

[0041] Furthermore, in order to reduce the stray inductance from the bonding point to the chip section, the bonding points of the positive power terminal 3 and the negative power terminal 4 with the substrate 1 are set close to the chips. Refer to Figure 4 and Figure 5 , the connection point of the positive power terminal 3 and the substrate 1 is set close to the upper half-bridge chip 21, so as to reduce the stray inductance between the bonding point of the positive power terminal 3 and the substrate 1 and the upper half-bridge chip 21. The connection point of the negative power terminal 4 and the substrate 1 is set close to the lower half-bridge chip 22, so as to reduce the stray inductance between the bonding point of the negative power terminal 4 and the substrate 1 and the lower half-bridge chip 22.

[0042] A power module with low stray inductance provided by an embodiment of the present application includes a substrate 1, chips, a positive power terminal 3, and a negative power terminal 4. The negative power terminal 4 and the positive power terminal 3 are parallel, and the projection of one of the negative power terminal 4 and the positive power terminal 3 on the substrate 1 completely covers the projection of the other on the substrate 1. In the circulating current of the power device, since the negative power terminal 4 and the positive power terminal 3 are parallel to each other, the magnetic fields generated by the two are mutually coupled, so that the stray inductance of the negative power terminal 4 and the positive power terminal 3 sections can be reduced. At the same time, by increasing the insulating layer 6, the distance between the positive power terminal 3 and the negative power terminal 4 can be further reduced, and the stray inductance can be further reduced. In addition, by setting the bonding points of the positive power terminal 3 and the negative power terminal 4 with the substrate 1 close to the chips, the stray inductance from the bonding point to the chip section can be reduced.

[0043] Obviously, the above embodiments are only examples for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or variations derived therefrom are still within the protection scope of the present invention.

Claims

1. A power module with low stray inductance, characterized in that: The invention comprises a substrate (1), on which a chip, a positive power terminal (3) and a negative power terminal (4) are connected, the negative power terminal (4) and the positive power terminal (3) are arranged in parallel, and the projection of one of the negative power terminal (4) and the positive power terminal (3) on the substrate (1) completely covers the projection of the other on the substrate (1), and the negative power terminal (4) and the positive power terminal (3) are arranged to be insulated from each other.

2. The low stray inductance power module according to claim 1, characterized in that: An insulating layer (6) is provided between the negative power terminal (4) and the positive power terminal (3).

3. The power module with low stray inductance according to claim 2, characterized in that: The insulating layer (6) is simultaneously attached to the negative power terminal (4) and the positive power terminal (3).

4. The power module with low stray inductance according to claim 1, characterized in that: The positive power terminal (3) and the negative power terminal (4) are respectively connected to the substrate (1) via pads (7).

5. The power module with low stray inductance according to claim 4, characterized in that: The positive power terminal (3) and the negative power terminal (4) respectively comprise a connecting portion and a main body portion, the thickness of the connecting portion is smaller than that of the main body portion, and the positive power terminal (3) and the negative power terminal (4) are respectively connected to the corresponding pad (7) via their respective connecting portions.

6. The power module with low stray inductance according to claim 1, characterized in that: The chip comprises an upper half-bridge chip (21) and a lower half-bridge chip (22), the positive power terminal (3) is connected to the positive electrode of the upper half-bridge chip (21), and the negative power terminal (4) is connected to the negative electrode of the lower half-bridge chip (22); The substrate (1) is also connected to a phase pole power terminal (5), and the phase pole power terminal (5) is connected to the negative electrode of the upper half bridge chip (21) and the positive electrode of the lower half bridge chip (22).

7. The power module with low stray inductance according to claim 6, characterized in that: A plurality of upper half-bridge chips (21) and a plurality of lower half-bridge chips (22) are provided respectively; the negative electrodes of the plurality of upper half-bridge chips (21) are connected to each other through a first connector (81) and are then connected to the phase power terminal (5); and the negative electrodes of the plurality of lower half-bridge chips (22) are connected to each other through a second connector (82) and are then connected to the negative power terminal (4).

8. The power module with low stray inductance according to claim 6, characterized in that: The connection point between the positive power terminal (3) and the substrate (1) is arranged close to the upper half-bridge chip (21); and the connection point between the negative power terminal (4) and the substrate (1) is arranged close to the lower half-bridge chip (22).

9. The power module with low stray inductance according to claim 1, characterized in that: The positive power terminal (3) and the negative power terminal (4) are respectively wide copper bars.

10. The power module with low stray inductance according to claim 1, characterized in that: The substrate (1) is a copper-clad substrate.

Images