A multi-layer metal insulating substrate for a power module and a preparation method thereof

Abstract

The present invention relates to a multi-layer metal insulating substrate of a power module and a preparation method thereof, comprising a functional layer, the functional layer comprising a lower bridge arm metal layer and an upper bridge arm metal layer respectively arranged on the left and right, a base layer further provided below the functional layer, and an offset layer further provided between the base layer and the functional layer, the offset layer comprising a first offset conductive plate, an offset insulating layer and a second offset conductive plate fixed laterally from top to bottom, the left side of the first offset conductive plate being electrically connected to the left side of the second offset conductive plate; the basic insulating plate, the offset insulating plate and the insulating sheet are all made of high thermal conductivity insulating material; the present invention can effectively reduce the switching energy loss of the power module, thereby significantly improving the switching performance of the power module to promote technological development in the high-frequency direction of the power module, and at the same time can increase the number of substrate layers as needed to fully utilize the vertical space and improve the interconnection density; and can also partition the substrate as needed to improve the heat dissipation effect.

Description

Technical Field

[0001] The present invention relates to the technical field of power modules, and in particular to a multi-layer metal insulating substrate of a power module and a preparation method thereof. Background Art

[0002] A power module is an electronic component that converts electrical energy into different power forms. Its main function is to convert DC power in equipment such as motor drives, UPS power supplies, inverters, and green energy into AC power, or to convert high-voltage, high-current DC power into low-voltage, low-current power. Power modules have the advantages of high efficiency, high stability, low cost, and low noise, providing strong support for power electronics, industrial automation, and green energy. The power module consists of two parts: the main circuit and the drive circuit. The main circuit usually consists of components such as chips, substrates, and heat sinks, and is used to control and adjust power parameters such as current and voltage. The drive circuit is used to provide control and protection signals, control the main circuit power switch, and make it output the required current and voltage to ensure safe operation of the circuit.

[0003] The substrate structure in the main circuit of the power module currently on the market is usually a three-layer structure, which is a metal conductive layer used to fix the chip and play the role of electricity, an insulating layer fixed to the bottom of the metal conductive layer, and a metal heat dissipation layer fixed to the bottom of the insulating layer. The processing technology of the metal insulating substrate of the existing power module is relatively complicated. Take the most mainstream DBC substrate as an example: it is made by eutectic sintering the ceramic layer and the copper layer at high temperature (1065℃), and finally, according to the wiring requirements, the circuit is formed by etching. However, bubbles will inevitably be generated on the bonding surface and will continue to form during subsequent use. The circuit becomes larger, so the process is complicated, the energy consumption is high, and the life is short; and because the current in the commutation circuit only flows through the metal conductive layer connected to the chip, there is only a single direction, and the path is also long, which will increase the amount of stray inductance on the path when flowing through the metal conductive layer, thereby increasing the total amount of stray inductance of the power module, and then causing the loss of switching energy to remain high, thereby ultimately reducing the switching performance, and thus seriously restricting the high-frequency development of the power module. Therefore, reducing parasitic inductance to reduce switching losses has become a key point that urgently needs to be broken through in the field of power module technology. Summary of the Invention

[0004] In view of the current status of the above-mentioned prior art, the technical problem to be solved by the present invention is to provide a multi-layer metal insulating substrate of a power module and its preparation method, which can significantly improve the switching performance to promote technological development in the high-frequency direction of the power module, and at the same time utilize the excellent bonding ability of high thermal conductivity insulating materials and adopt heating and pressurizing methods to stack and fix the functional layer, the offset layer and the base layer together to realize the preparation of the multi-layer substrate more simply, and the preparation process is more energy-saving and environmentally friendly.

[0005] The technical solution adopted by the present invention to solve the above technical problems is: a multi-layer metal insulation substrate for a power module, including a functional layer, the functional layer including a lower bridge arm metal layer and an upper bridge arm metal layer respectively arranged on the left and right sides, the upper bridge arm metal layer including a first functional conductive plate arranged horizontally and a DC positive terminal fixed to the right side of the first functional conductive plate, and the lower bridge arm metal layer including a second functional conductive plate arranged horizontally and an AC terminal fixed to the left side of the top of the second functional conductive plate, characterized in that:

[0006] A base layer is also provided below the functional layer, and the base layer includes a laterally arranged base insulating plate and a base metal plate laterally fixed to the bottom of the base insulating plate. The bottoms of the first functional conductive plate and the second functional conductive plate are both fixed to the top of the base insulating plate.

[0007] A compensation layer is also provided between the base layer and the functional layer. The compensation layer includes a first compensation conductive plate, a compensation insulating layer, and a second compensation conductive plate fixed laterally from top to bottom. The bottom of the second compensation conductive plate is fixed on the top of the base insulating plate. The first compensation conductive plate, the compensation insulating layer, and the second compensation conductive plate are respectively provided with a first accommodating cavity, a second accommodating cavity, and a third accommodating cavity that cooperate with each other. The first functional conductive plate and the second functional conductive plate are both arranged in the first accommodating cavity, the second accommodating cavity, and the third accommodating cavity; the left side of the first compensation conductive plate is electrically connected to the left side of the second compensation conductive plate.

[0008] Preferably, a first positioning groove is provided on the right inner wall of the first accommodating cavity and is located below the DC positive terminal. Correspondingly, a second positioning groove is provided on the right inner wall of the second accommodating cavity and is located below the first positioning groove. The offset layer also includes a DC negative terminal fixed on the right side of the top of the second offsetting conductive plate and arranged inside the second positioning groove, and an insulating sheet fixed between the DC positive terminal and the DC negative terminal and located inside the first positioning groove.

[0009] Preferably, a first groove is formed on the left edge of the first functional conductive plate, and correspondingly, a second groove that cooperates with the first groove is formed on the right edge of the second functional conductive plate.

[0010] Preferably, the offset layer further includes a plurality of jumper wires arranged sequentially from front to back, and both ends of each jumper wire are electrically connected to the left edge of the first offset conductive plate and the left edge of the second offset conductive plate respectively.

[0011] Preferably, the basic insulation board, the offset insulation board and the insulation sheet are all made of a high thermal conductivity insulation material.

[0012] A method for preparing a multi-layer metal insulating substrate for a power module, characterized by comprising the following steps:

[0013] S1. Making the base layer: Take a piece of metal sheet with a complete shape as the base metal plate, and stick the base insulation board on top of the base metal plate;

[0014] S2. Making functional layer:

[0015] S2.1. Select a metal sheet of appropriate size based on the number of upper bridge arm chips as the first functional conductive plate. Then, solder the DC positive terminal to the top right side of the first functional conductive plate.

[0016] S2.2. Select a metal sheet of appropriate size as the second functional conductive plate based on the number of chips in the lower bridge arm. Then, secure the AC terminal to the top left side of the second functional conductive plate.

[0017] S3. Make the offset layer:

[0018] S3.1. First, a first accommodating cavity, a second accommodating cavity, and a third accommodating cavity are respectively machined on the first offset conductive plate, the offset insulating plate, and the second offset conductive plate;

[0019] S3.2. Then, stack the first offset conductive plate, the offset insulating plate, and the second offset conductive plate in sequence and adhere them to the top of the base insulating plate;

[0020] S3.3. Finally, weld the two ends of each bridging wire to the left edge of the first offset conductive plate and the left edge of the second offset conductive plate to electrically connect the two.

[0021] S4. Integrate the base layer, functional layer and offset layer by hot pressing in steps or all at once;

[0022] S4.1. If a step-by-step hot pressing method is used, first heat and pressurize the first offset conductive plate, the offset insulating plate, and the second offset conductive plate so that the offset insulating plate is cured by the characteristics of its own material, and then fix the first offset conductive plate, the offset insulating plate, and the second offset conductive plate together; then fix the second offset conductive plate on the top of the basic insulating plate to achieve insulation between layers; finally, place the first functional conductive plate and the second functional conductive plate in the first accommodating cavity, the second accommodating cavity, and the third accommodating cavity and stick them on the top of the basic insulating plate and heat and pressurize them so that the basic insulating plate is cured by the characteristics of its own material, and then fix the first functional conductive plate and the second functional conductive plate on the basic insulating plate.

[0023] S4.2. If the simultaneous hot pressing method is adopted, first place the first functional conductive plate and the second functional conductive plate in the first accommodating cavity, the second accommodating cavity and the third accommodating cavity and stick them on the top of the basic insulating plate; then heat and pressurize the first offset conductive plate, the offset insulating plate, the second offset conductive plate, the first functional conductive plate and the second functional conductive plate at the same time, and then use the curing characteristics of the offset insulating plate and the basic insulating plate's own materials to fix the first offset conductive plate, the offset insulating plate, the second offset conductive plate, the first functional conductive plate and the second functional conductive plate on the basic insulating plate at one time.

[0024] Preferably, the step S2.1 further comprises opening a first groove on the left edge of the first functional conductive plate for accommodating the right portion of a bonding wire unit cooperating with each upper bridge arm chip.

[0025] Preferably, the step S2.2 further comprises providing a second groove cooperating with the first groove on the right edge of the second functional conductive plate for accommodating the left portion of the bonding wire unit cooperating with each lower bridge arm chip.

[0026] Preferably, the step S3.3 further comprises welding two ends of each bridging wire to the left edge of the first offset conductive plate and the left edge of the second offset conductive plate respectively to electrically connect the two.

[0027] Compared with the prior art, the advantages of the present invention are: the present invention introduces mutual inductance cancellation effect around the chip by setting up a cancellation layer, and then reduces the stray inductance of the power module through the mutual inductance cancellation effect, thereby effectively reducing the switching energy loss of the power module, and then significantly improving the switching performance of the power module to promote technological development in the high-frequency direction of the power module; it can also increase the number of substrate layers as needed to fully utilize the vertical space and improve the interconnection density on the basis of ensuring the mutual inductance cancellation structure, and has good design flexibility; it can also partition the substrate and surround the chip as needed, thereby increasing the thickness of the copper layer under the chip to improve the heat dissipation effect; in addition, it also reasonably utilizes the excellent bonding ability of high thermal conductivity insulating materials and adopts heating and pressurizing methods to stack and fix the functional layer, the cancellation layer and the base layer together to realize the preparation of multi-layer substrates in a relatively simple way. The temperature and pressure required for the preparation process are relatively mild and there is less material waste, which is more energy-saving and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is the exploded structural diagram of the right front side of the present invention;

[0029] Figure 2 It is a preparation flow chart of the present invention. DETAILED DESCRIPTION

[0030] Unless otherwise defined, the technical or scientific terms used in the present invention shall have the usual meanings understood by persons of ordinary skill in the field to which the present invention belongs. The words "first", "second" and similar terms used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0031] In order to keep the following description of the embodiments of the present invention clear and concise, detailed descriptions of known functions and known components are omitted.

[0032] like Figure 1 As shown, a multi-layer metal insulation substrate of a power module includes a functional layer, the functional layer includes a lower bridge arm metal layer 2 and an upper bridge arm metal layer 1 respectively arranged on the left and right, the upper bridge arm metal layer 1 includes a first functional conductive plate 101 arranged horizontally and a DC positive terminal 103 fixed to the right side of the first functional conductive plate 101, the lower bridge arm metal layer 2 includes a second functional conductive plate 201 arranged horizontally and an AC terminal 203 fixed to the left side of the top of the second functional conductive plate 201; a base layer is further provided below the functional layer, the base layer includes a base insulating plate 4 arranged horizontally and a base metal plate 5 fixed horizontally to the bottom of the base insulating plate 4, the bottom of the first functional conductive plate 101 and the second functional conductive plate 201 are connected to each other. The first and second functional conductive plates 101 and 201 are both arranged in the first, second and third accommodating cavities 61, 71 and 81, respectively; the left side of the first offsetting conductive plate 6 is electrically connected to the left side of the second offsetting conductive plate 8.

[0033] A first positioning groove 62 is provided on the right inner wall of the first accommodating cavity 61 and is located below the DC positive terminal 103. Correspondingly, a second positioning groove 72 is provided on the right inner wall of the second accommodating cavity 71 and is located below the first positioning groove 62. The offset layer also includes a DC negative terminal 25 fixed on the right side of the top of the second offsetting conductive plate 8 and arranged inside the second positioning groove 72, and an insulating sheet 24 fixed between the DC positive terminal 103 and the DC negative terminal 25 and located inside the first positioning groove 62.

[0034] A first groove 1011 is defined on the left edge of the first functional conductive plate 101 , and correspondingly, a second groove 2011 cooperating with the first groove 1011 is defined on the right edge of the second functional conductive plate 201 .

[0035] The offset layer further includes a plurality of jumper wires 9 arranged sequentially from front to back, and two ends of each jumper wire 9 are electrically connected to the left edge of the first offset conductive plate 6 and the left edge of the second offset conductive plate 8 respectively.

[0036] The basic insulating plate 4 , the offset insulating plate 7 and the insulating sheet 24 are all made of a highly thermally conductive insulating material.

[0037] like Figure 2 As shown, a method for preparing a multi-layer metal insulating substrate of a power module includes the following steps:

[0038] S1. Fabricate the base layer: Take a well-shaped metal sheet as the base metal plate 5 (on the outside of the module, away from the chip), and attach a base insulation plate 4 made of a high thermal conductivity insulation material on top of the base metal plate 5;

[0039] S2. Making functional layer:

[0040] S2.1. Select a metal sheet of appropriate size as the first functional conductive plate 101 based on the number of upper-arm chips. The thickness of the first functional conductive plate 101 can be relatively thick to fully dissipate the heat generated by the chips. Define a first groove 1011 on the left edge of the first functional conductive plate 101 to accommodate the right portion of the bonding wire unit 23 that mates with each upper-arm chip. Solder the DC positive terminal 103 to the top right side of the first functional conductive plate 101.

[0041] S2.2. Select a metal sheet of appropriate size as the second functional conductive plate 201 based on the number of lower-arm chips. The thickness of the second functional conductive plate 201 can be relatively thick to fully dissipate the heat generated by the chips. A second groove 2011 is formed on the right edge of the second functional conductive plate 201 to mate with the first groove 1011 to accommodate the left portion of the bonding wire unit 23 that mates with each lower-arm chip. Then, the AC terminal 203 is fixed to the top left side of the second functional conductive plate 201.

[0042] S3. Make the offset layer:

[0043] S3.1. First, a first accommodating cavity 61, a second accommodating cavity 71, and a third accommodating cavity 81 are respectively machined on the first offset conductive plate 6, the offset insulating plate 7, and the second offset conductive plate 8;

[0044] S3.2. Then, stack the first offset conductive plate 6, the offset insulating plate 7, and the second offset conductive plate 8 in sequence and adhere them to the top of the base insulating plate 4;

[0045] S3.3. Finally, weld the two ends of each bonding wire 9 to the left edge of the first offset conductive plate 6 and the left edge of the second offset conductive plate 8 to electrically connect them.

[0046] S4. Integrate the base layer, functional layer, and offset layer by hot pressing in steps or all at once. The integrated structure can handle more complex and diverse electrical interconnection functions, improving the flexibility of module design.

[0047] S4.1. If a step-by-step hot pressing method is adopted, the first offset conductive plate 6, the offset insulating plate 7 and the second offset conductive plate 8 are first heated and pressurized so that the offset insulating plate 7 is solidified by the characteristics of its own material, and then the first offset conductive plate 6, the offset insulating plate 7 and the second offset conductive plate 8 are fixed together; then the second offset conductive plate 8 is fixed on the top of the basic insulating plate 4 to achieve insulation between layers; finally, the first functional conductive plate 101 and the second functional conductive plate 201 are placed in the first accommodating cavity 61, the second accommodating cavity 71 and the third accommodating cavity 81 and are both pasted on the top of the basic insulating plate 4 and heated and pressurized so that the basic insulating plate 4 is solidified by the characteristics of its own material, and then the first functional conductive plate 101 and the second functional conductive plate 201 are fixed on the basic insulating plate 4.

[0048] S4.2. If the hot pressing method is adopted, the first functional conductive plate 101 and the second functional conductive plate 201 are first placed in the first accommodating cavity 61, the second accommodating cavity 71 and the third accommodating cavity 81 and are pasted on the top of the basic insulating plate 4; then the first offsetting conductive plate 6, the offsetting insulating plate 7, the second offsetting conductive plate 8, the first functional conductive plate 101 and the second functional conductive plate 201 are heated and pressurized at the same time, and then the curing characteristics of the offsetting insulating plate 7 and the basic insulating plate 4 are used to fix the first offsetting conductive plate 6, the offsetting insulating plate 7, the second offsetting conductive plate 8, the first functional conductive plate 101 and the second functional conductive plate 201 on the basic insulating plate 4 at one time.

[0049] Packaging steps:

[0050] A plurality of upper arm chips 102 are fixed on top of the first functional conductive plate 101 in the upper arm metal layer 1, and the gate region or source region of each upper arm chip 102 is electrically connected to a plurality of first control terminals 104; similarly, a plurality of lower arm chips 202 are fixed on top of the second functional conductive plate 201 in the lower arm metal layer 2, and the gate region or source region of each lower arm chip 202 is electrically connected to a plurality of second control terminals 204.

[0051] A first metal conductive block 14 is fixed to the top source region of each upper bridge arm chip 102 and the top source region of each lower bridge arm chip 202, and a laterally distributed third insulating plate 11 is arranged above the upper bridge arm metal layer 1 and the lower bridge arm metal layer 2, and a lower bridge arm conductive plate 12 and an upper bridge arm conductive plate 13 arranged on the left and right sides respectively are fixed to the bottom of the third insulating plate 11.

[0052] The ends of the first metal conductive blocks 14 located on each upper bridge arm chip 102 are fixed to the bottom of the upper bridge arm conductive plate 13 so that the top source region of each upper bridge arm chip 102 is electrically connected to the upper bridge arm conductive plate 13 through a first metal conductive block 14; the ends of the first metal conductive blocks 14 located on each lower bridge arm chip 202 are fixed to the bottom of the lower bridge arm conductive plate 12 so that the top source region of each lower bridge arm chip 202 is electrically connected to the lower bridge arm conductive plate 12 through a first metal conductive block 14.

[0053] Several second metal conductive blocks 15 are also fixed on the top of the second functional conductive plate 201 and the first offset conductive plate 6. The end of each second metal conductive block 15 located on the second functional conductive plate 201 is fixed to the bottom of the upper bridge arm conductive plate 13 to electrically connect the second functional conductive plate 201 with the upper bridge arm conductive plate 13. The end of each second metal conductive block 15 located on the first offset conductive plate 6 is fixed to the bottom of the lower bridge arm conductive plate 12 to electrically connect the first offset conductive plate 6 with the lower bridge arm conductive plate 12.

[0054] If a radiator is to be installed on the top, a metal connecting plate 10 needs to be fixed laterally on the top of the third insulating plate 11, or the metal connecting plate 10 can be directly replaced with a radiator to achieve heat dissipation without a bottom plate, which reduces the number of layers and improves the heat dissipation capacity.

[0055] Working principle:

[0056] The current of the commutation loop is input from the DC positive terminal 103 to the first functional conductive plate 101 and flows into each upper bridge arm chip 102. The current output from the source region at the top of each upper bridge arm chip 102 is conducted to the upper bridge arm conductive plate 13 through a first metal conductive block 14, and then conducted to the second functional conductive plate 201 through each second metal conductive block 15 fixed on the second functional conductive plate 201; then, the current output from the source region at the top of each lower bridge arm chip 202 is also conducted to the lower bridge arm conductive plate 12 through a first metal conductive block 14, and then conducted to the first offset conductive plate 6 through each second metal conductive block 15 fixed on the top of the first offset conductive plate 6, and then conducted to the second offset conductive plate 8 through each bonding wire 9, and finally conducted to the DC negative terminal 103. Terminal 25 is output outward; in the above process, the area where mutual inductance cancellation occurs is between the first canceling conductive plate 6 and the second canceling conductive plate 8, because the current conducted to the second canceling conductive plate 8 is concentrated on its upper surface and the direction is from left to right, while the current conducted to the first canceling conductive plate 6 is concentrated on its lower surface and the direction is from right to left. In this way, based on the principle of proximity effect, the magnetic fields generated by the currents of the above two commutation circuits are in opposite directions, and then mutual inductance cancellation occurs, thereby reducing the total loop inductance, thereby reducing parasitic parameters, reducing losses, and improving switching performance; if single-sided heat dissipation is adopted, the heat sink can be installed at the bottom of the base metal plate 5; if double-sided heat dissipation is adopted, a heat sink needs to be installed on the top of the second metal heat dissipation plate 10.

[0057] The present invention introduces mutual inductance cancellation effect around the chip by arranging a cancellation layer, and then reduces the stray inductance of the power module through the mutual inductance cancellation effect, thereby effectively reducing the switching energy loss of the power module, and then significantly improving the switching performance of the power module to promote technological development in the high-frequency direction of the power module; it can also increase the number of substrate layers as needed to fully utilize the vertical space and improve the interconnection density on the basis of ensuring the mutual inductance cancellation structure, and has good design flexibility; it can also partition the substrate and surround the chip as needed, thereby increasing the thickness of the copper layer under the chip to improve the heat dissipation effect; in addition, it also reasonably utilizes the excellent bonding ability of high thermal conductivity insulating materials and adopts heating and pressurizing methods to stack and fix the functional layer, the cancellation layer and the base layer together to realize the preparation of multi-layer substrates in a relatively simple way. The temperature and pressure required for the preparation process are relatively mild, with less material waste, and more energy-saving and environmentally friendly.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A multilayer metal insulation substrate for a power module, comprising a functional layer, the functional layer comprising a lower bridge arm metal layer and an upper bridge arm metal layer, respectively disposed on the left and right sides, the upper bridge arm metal layer comprising a first functional conductive plate disposed laterally and a DC positive terminal fixed to the right side of the first functional conductive plate, and the lower bridge arm metal layer comprising a second functional conductive plate disposed laterally and an AC terminal fixed to the left side of the top of the second functional conductive plate, characterized in that: A base layer is further provided below the functional layer, the base layer comprising a transversely arranged base insulating plate and a base metal plate transversely fixed to the bottom of the base insulating plate, the bottoms of the first functional conductive plate and the second functional conductive plate are both fixed to the top of the base insulating plate; A compensation layer is also provided between the base layer and the functional layer. The compensation layer includes a first compensation conductive plate, a compensation insulating layer, and a second compensation conductive plate fixed laterally from top to bottom. The bottom of the second compensation conductive plate is fixed on the top of the base insulating plate. The first compensation conductive plate, the compensation insulating layer, and the second compensation conductive plate are respectively provided with a first accommodating cavity, a second accommodating cavity, and a third accommodating cavity that cooperate with each other. The first functional conductive plate and the second functional conductive plate are both arranged in the first accommodating cavity, the second accommodating cavity, and the third accommodating cavity; the left side of the first compensation conductive plate is electrically connected to the left side of the second compensation conductive plate.

2. The multi-layer metal insulation substrate of a power module according to claim 1, characterized in that: A first positioning groove is provided on the right inner wall of the first accommodating cavity and is located below the DC positive terminal. Correspondingly, a second positioning groove is provided on the right inner wall of the second accommodating cavity and is located below the first positioning groove. The offset layer also includes a DC negative terminal fixed to the right side of the top of the second offsetting conductive plate and arranged inside the second positioning groove, and an insulating sheet fixed between the DC positive terminal and the DC negative terminal and located inside the first positioning groove.

3. The multi-layer metal insulation substrate of a power module according to claim 1, characterized in that: A first groove is formed on the left edge of the first functional conductive plate, and correspondingly, a second groove that cooperates with the first groove is formed on the right edge of the second functional conductive plate.

4. The multi-layer metal insulation substrate of a power module according to claim 1, characterized in that: The offset layer also includes a plurality of jumper wires arranged sequentially from front to back, and the two ends of each jumper wire are electrically connected to the left edge of the first offset conductive plate and the left edge of the second offset conductive plate respectively.

5. The multi-layer metal insulation substrate of a power module according to claim 2, characterized in that: The basic insulating plate, the offset insulating plate and the insulating sheet are all made of a high thermal conductivity insulating material.

6. A method for preparing a multi-layer metal insulating substrate for a power module, characterized in that: The following steps are involved: S1. Making the base layer: Take a piece of metal sheet with a complete shape as the base metal plate, and stick the base insulation board on top of the base metal plate; S2. Making functional layer: S2.

1. Select a metal sheet of appropriate size based on the number of upper bridge arm chips as the first functional conductive plate. Then, solder the DC positive terminal to the top right side of the first functional conductive plate. S2.

2. Select a metal sheet of appropriate size as the second functional conductive plate based on the number of chips in the lower bridge arm. Then, secure the AC terminal to the top left side of the second functional conductive plate. S3. Make the offset layer: S3.

1. First, a first accommodating cavity, a second accommodating cavity, and a third accommodating cavity are respectively machined on the first offset conductive plate, the offset insulating plate, and the second offset conductive plate; S3.

2. Then, stack the first offset conductive plate, the offset insulating plate, and the second offset conductive plate in sequence and adhere them to the top of the base insulating plate; S3.

3. Finally, weld the two ends of each bridging wire to the left edge of the first offset conductive plate and the left edge of the second offset conductive plate to electrically connect the two. S4. Integrate the base layer, functional layer and offset layer by hot pressing in steps or all at once; S4.

1. If a step-by-step hot pressing method is used, first heat and pressurize the first offset conductive plate, the offset insulating plate, and the second offset conductive plate so that the offset insulating plate solidifies due to the characteristics of its own material, and then fix the first offset conductive plate, the offset insulating plate, and the second offset conductive plate together; then fix the second offset conductive plate on top of the base insulating plate to achieve interlayer insulation; finally, place the first functional conductive plate and the second functional conductive plate in the first accommodating cavity, the second accommodating cavity, and the third accommodating cavity, adhere them to the top of the base insulating plate, and heat and pressurize them so that the base insulating plate solidifies due to the characteristics of its own material, and then fix the first functional conductive plate and the second functional conductive plate to the base insulating plate; S4.

2. If the simultaneous hot pressing method is adopted, first place the first functional conductive plate and the second functional conductive plate in the first accommodating cavity, the second accommodating cavity and the third accommodating cavity and stick them on the top of the basic insulating plate; then heat and pressurize the first offset conductive plate, the offset insulating plate, the second offset conductive plate, the first functional conductive plate and the second functional conductive plate at the same time, and then use the curing characteristics of the offset insulating plate and the basic insulating plate's own materials to fix the first offset conductive plate, the offset insulating plate, the second offset conductive plate, the first functional conductive plate and the second functional conductive plate on the basic insulating plate at one time.

7. The method for preparing a multi-layer metal insulating substrate for a power module according to claim 6, characterized in that: The step S2.1 further includes forming a first groove on the left edge of the first functional conductive plate to accommodate the right portion of the bonding wire unit cooperating with each upper bridge arm chip.

8. The method for preparing a multi-layer metal insulating substrate for a power module according to claim 6, wherein: The step S2.2 further includes forming a second groove on the right edge of the second functional conductive plate to cooperate with the first groove for accommodating the left portion of the bonding wire unit that cooperates with each lower bridge arm chip.

9. The method for preparing a multi-layer metal insulating substrate for a power module according to claim 6, wherein: The step S3.3 further includes welding two ends of each bridging wire to the left edge of the first offset conductive plate and the left edge of the second offset conductive plate to electrically connect the two.

Images