A single-in-line embedded power module

Abstract

This invention discloses a single-transistor embedded power module, comprising multiple upper-bridge power transistors, multiple lower-bridge power transistors, a lower copper foil, a middle copper foil, an upper copper foil, a first insulating substrate, and a second insulating substrate. The lower copper foil is connected to the DC input terminal and AC output terminal of the upper bridge arm, the middle copper foil is connected to the DC output terminal of the lower bridge arm, and the upper copper foil includes a control signal wiring layer connected to the control signals of the power transistors. Openings are provided on both the lower and middle copper foils. The upper-bridge power transistors are positioned below the openings in the lower copper foil, and the lower-bridge power transistors are positioned below the openings in the middle copper foil. The power transistors are connected to each copper foil layer via copper pillars. This invention, through a three-dimensional loop layout, effectively reduces the area enclosed by the power loop and increases the line width, significantly reducing parasitic inductance and fully leveraging the high-frequency performance advantages of silicon carbide power chips.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and more specifically, to a power module packaging structure, and particularly to a single-tube embedded power module. Background Technology

[0002] As the core component of power electronic systems for power conversion and control, the performance of power modules directly affects the conversion efficiency, reliability, and miniaturization of the entire system. Silicon carbide (SiC) power chips, with their significant advantages such as large bandgap, strong breakdown electric field, high thermal conductivity, and fast switching speed, exhibit superior performance compared to traditional silicon-based chips in high-voltage, high-current, and high-temperature operating environments, and have become the core device for next-generation power modules.

[0003] However, current silicon carbide power module packaging typically employs a layer-by-layer stacked structure consisting of silicon carbide chips, solder layers, copper-clad ceramic insulating substrates, and heat sinks. Electrical interconnection between chips is achieved through wire bonding. Due to this planar layout, the power circuit area is large and the wiring width is limited, resulting in long power circuit paths and parasitic inductances typically reaching 10nH to 20nH. During high-frequency switching, excessive parasitic inductance can easily induce voltage spikes, causing electrical stress damage to the power chip. This not only restricts the effective utilization of the high-frequency switching advantages of silicon carbide power chips but also severely impacts the performance and operational stability of the power module in high-frequency applications.

[0004] There is currently no effective solution to the problem of excessive parasitic inductance in silicon carbide power modules caused by their packaging structure in the existing technologies. Summary of the Invention

[0005] The purpose of this invention is to provide a single-tube embedded power module to at least solve the technical problem of excessive parasitic inductance in the existing power module packaging structure, which affects the high-frequency performance of silicon carbide power chips.

[0006] A single-transistor embedded power module, comprising,

[0007] Multiple power transistors, lower copper foil, middle copper foil, upper copper foil, first insulating substrate and second insulating substrate;

[0008] The lower copper foil is connected to the upper bridge arm DC input terminal and AC output terminal, the middle copper foil is connected to the lower bridge arm DC output terminal, and the upper copper foil includes a control signal wiring layer, which is connected to the control signal of the power transistor.

[0009] The lower copper foil has multiple first openings, and the middle copper foil has multiple second openings;

[0010] Both the first insulating substrate and the second insulating substrate are composed of a first copper layer, a ceramic layer and a second copper layer stacked sequentially.

[0011] The power single tube includes an upper bridge arm power single tube and a lower bridge arm power single tube;

[0012] The drains of the plurality of upper bridge arm power transistors are respectively connected to the first copper layer of the first insulating substrate, and the drains of the plurality of lower bridge arm power transistors are respectively connected to the first copper layer of the second insulating substrate. The upper bridge arm power transistors and the lower bridge arm power transistors are arranged symmetrically.

[0013] Each of the aforementioned power transistors includes a power chip, a connection layer, a conductive layer, and a molding compound;

[0014] The upper bridge arm power transistor is disposed below the first opening, the first copper layer of the first insulating substrate is connected to the lower copper foil, the source of the upper bridge arm power transistor is connected to the lower copper foil, and the control electrode of the upper bridge arm power transistor is connected to the upper copper foil.

[0015] The lower bridge arm power transistor is disposed below the second opening, the second copper layer of the second insulating substrate is connected to the lower copper foil, the source of the lower bridge arm power transistor is connected to the middle copper foil, and the control electrode of the lower bridge arm power transistor is connected to the upper copper foil.

[0016] Specifically, the power transistor is connected to the first copper layer, the upper copper foil, the middle copper foil, and the lower copper foil of the first insulating substrate through copper pillars.

[0017] Furthermore, the copper pillar is cylindrical with a diameter of 0.1 mm to 0.3 mm.

[0018] Specifically, thermally conductive copper layers are respectively provided on the bottom of the first insulating substrate and the bottom of the second insulating substrate.

[0019] Furthermore, the vertical distance between the first insulating substrate and the second insulating substrate is greater than 1.5 mm.

[0020] Furthermore, an insulating medium is filled between the upper copper foil and the thermally conductive copper layer.

[0021] Furthermore, the temperature resistance of the insulating medium is not lower than 200℃.

[0022] Furthermore, the connecting layer of the power transistor is made of silver, and the conductive layer is made of copper or molybdenum copper.

[0023] Specifically, the lower copper foil, the middle copper foil, and the upper copper foil constitute a multilayer copper foil wiring layer of the PCB board.

[0024] Furthermore, the PCB board has an 8-layer structure.

[0025] The single-tube embedded power module of the present invention has the following advantages compared with the prior art:

[0026] (1) This invention connects the power single tube to the insulating ceramic substrate and integrates it inside the packaging structure. It combines the lower copper foil with the upper bridge arm DC input terminal and AC output terminal, the middle copper foil with the lower bridge arm DC output terminal and the upper copper foil with the control signal, and realizes the integrated packaging of the power single tube and the multi-layer circuit board, thus constructing a three-dimensional power circuit layout.

[0027] (2) Through the three-dimensional circuit design, the present invention can effectively reduce the area enclosed by the power circuit and increase the line width, thereby significantly reducing the parasitic inductance of the circuit, avoiding electrical stress damage to the power chip caused by voltage spikes, and giving full play to the high-frequency switching performance advantages of silicon carbide power chips;

[0028] (3) The present invention, through the symmetrical arrangement of the power tubes in the upper and lower bridge arms and the spacing between the insulating substrates, is conducive to balancing the circuit parameters and further improving the working stability and reliability of the power module. Attached Figure Description

[0029] Figure 1 This is a connection diagram of the single-tube embedded power module of the present invention;

[0030] Figure 2 This is a schematic diagram of the power transistor structure in the single-transistor embedded power module of the present invention;

[0031] Figure 3 This is a schematic diagram of the internal single-tube distribution of the first embodiment of the single-tube embedded power module of the present invention;

[0032] Figure 4 This is a schematic diagram of the internal single-tube distribution of the second embodiment of the single-tube embedded power module of the present invention;

[0033] Figure 5 This is a schematic diagram of the external appearance of the first embodiment of the single-tube embedded power module of the present invention;

[0034] Figure 6 This is a schematic diagram of the external appearance of the second embodiment of the single-tube embedded power module of the present invention. Detailed Implementation

[0035] The specific embodiments of this invention will be further described in detail below with reference to the accompanying drawings.

[0036] Specific structure of a power single transistor

[0037] Figure 2 This is a schematic diagram of the power transistor structure in the single-transistor embedded power module of the present invention. (See attached diagram.) Figure 2 As shown, each power transistor 8 includes a power chip 801, a molding compound 802, a conductive layer 803, a connecting layer 804, and a signal terminal 805. The power chip 801 is a silicon carbide (SiC) power chip and is the core component for power conversion. The conductive layer 803 is used to establish the electrode leads of the power chip 801. The material of the conductive layer 803 is preferably copper or molybdenum copper to ensure good electrical and thermal conductivity. The connecting layer 804 is disposed between the power chip 801 and the conductive layer 803 to achieve electrical connection and heat conduction. The material of the connecting layer 804 is preferably silver (i.e., a silver layer), as silver has excellent electrical and thermal conductivity and high-temperature reliability. The molding compound 802 encapsulates the power chip 801 and the connecting layer 804 to seal and protect the power chip 801, preventing external environmental contamination and mechanical damage. The signal terminal 805 is located at the control terminal of the power transistor 8. One end is electrically connected to the control electrode (gate) of the power chip 801, and the other end extends to the outside of the molding compound 802. It is used to introduce the external control signal 7 into the power chip 801 to control the on / off state of the power transistor 8.

[0038] Example 1

[0039] Figure 1 This is a connection diagram of the single-tube embedded power module of the present invention. Figure 1 As shown, the present invention provides a single-tube embedded power module, including: multiple upper bridge arm power tubes, multiple lower bridge arm power tubes, a lower copper foil 63, a middle copper foil 62, an upper copper foil 61, a first insulating substrate 5, and a second insulating substrate 4.

[0040] The lower copper foil 63 is connected to the upper bridge arm DC terminal 1 (DC+) and AC output terminal 3 (AC). The middle copper foil 62 is connected to the lower bridge arm DC output terminal 2 (DC-). The upper copper foil 61 is connected to the control signal 7. The lower copper foil 63 has multiple first openings, and the middle copper foil 62 has multiple second openings.

[0041] Both the first insulating substrate 5 and the second insulating substrate 4 are composed of a first copper layer (41, 51), a ceramic layer (42, 52), and a second copper layer (43, 53) stacked sequentially (i.e., copper-clad ceramic insulating substrates, which can be DBC substrates (direct copper-clad ceramic substrates) or AMB substrates (active metal brazed ceramic substrates). The drains of multiple upper-arm power transistors are respectively connected to the first copper layer 51 of the first insulating substrate 5; the drains of multiple lower-arm power transistors are respectively connected to the first copper layer 41 of the second insulating substrate 4. The upper-arm and lower-arm power transistors are arranged symmetrically.

[0042] In terms of the assembly structure, the upper bridge arm power transistor is located below the first opening of the lower copper foil 63, the first copper layer 51 of the first insulating substrate 5 is connected to the lower copper foil 63, the source of the upper bridge arm power transistor is connected to the lower copper foil 63, and the control electrode (gate) of the upper bridge arm power transistor is connected to the upper copper foil 61.

[0043] The lower bridge arm power transistor is located below the second opening of the intermediate layer copper foil 62. The second copper layer of the second insulating substrate 4 is connected to the lower layer copper foil 63. The source of the lower bridge arm power transistor is connected to the intermediate layer copper foil 62, and the control electrode (gate) of the lower bridge arm power transistor is connected to the upper layer copper foil 61.

[0044] The power transistor 8 is connected to the first copper layer 51, upper copper foil 61, middle copper foil 62, and lower copper foil 63 of the first insulating substrate 5 via copper pillars. Specifically, the power transistor control signal connection copper pillar 71 is used to connect the control electrode of the power transistor 8 to the upper copper foil 61; the power transistor source connection copper pillars 72 and 73 are used to connect the source electrode of the power transistor 8 to the middle copper foil 62 and the lower copper foil 63, respectively; and the terminal connection copper pillar 74 is used to connect the terminal to the corresponding copper foil layer. The copper pillars are preferably cylindrical, with a diameter of 0.1 mm to 0.3 mm.

[0045] A thermally conductive copper layer is provided at the bottom of the first insulating substrate 5 and the bottom of the second insulating substrate 4, respectively, to conduct the heat generated by the power tube 8 downwards to the heat dissipation structure. The vertical spacing between the first insulating substrate 5 and the second insulating substrate 4 is greater than 1.5 mm to ensure sufficient electrical insulation strength.

[0046] An insulating medium is filled between the upper copper foil 61 and the thermally conductive copper layer. This insulating medium also fills the gaps between the various components inside the power module. The temperature resistance of this insulating medium is not less than 200℃ to ensure the insulation reliability and long-term stability of the power module in high-temperature operating environments.

[0047] In this embodiment, the lower copper foil 63, the middle copper foil 62, and the upper copper foil 61 constitute the multilayer copper foil wiring layers of the PCB board 6. The PCB board 6 is preferably an 8-layer structure, wherein the upper copper foil 61, the middle copper foil 62, and the lower copper foil 63 are different wiring layers of the PCB board 6.

[0048] Figure 3 This is a schematic diagram of the internal single-transistor distribution of the first embodiment of the single-transistor embedded power module of the present invention. (See diagram below.) Figure 3 As shown, the distribution of each power transistor 8 on the insulating substrate in the first embodiment is displayed from an internal perspective. Figure 3 The image shows the positions of the DC+ upper bridge arm DC terminals 101 and 102, and the distribution of the thermal via pads 501 and 502 on the surface of the first insulating substrate.

[0049] Figure 5 This is a schematic diagram of the external appearance of the first embodiment of the single-tube embedded power module of the present invention. Figure 5 As shown, the overall package shape of the first embodiment is displayed from the perspective of the external shape, showing the position and distribution of the DC+ upper bridge arm DC terminal 1, the DC- lower bridge arm DC terminal 2, and the AC terminal 3.

[0050] Example 2

[0051] Figure 4 This is a schematic diagram of the internal single-transistor distribution of the second embodiment of the single-transistor embedded power module of the present invention. Figure 6 This is a schematic diagram of the external appearance of a second embodiment of the single-tube embedded power module of the present invention. Figure 4 and Figure 6 As shown, in another embodiment, the first insulating substrate 5 is further integrated with a first insulating substrate NTC surface pad 503 and a first insulating substrate NTC 504 for real-time monitoring of the operating temperature of the power module, so as to facilitate system temperature management and over-temperature protection.

[0052] The second insulating substrate 4 is provided with surface thermal vias 401 and 402, which are also used to enhance heat dissipation.

[0053] The other structures in this embodiment are the same as in Embodiment 1, and will not be described again here.

[0054] Working principle:

[0055] When the single-tube embedded power module provided by this invention is working, the upper bridge arm power tube and the lower bridge arm power tube are alternately turned on under the control of the control signal 7 to realize power conversion.

[0056] During the conduction of the upper bridge arm, the current path is: DC + upper bridge arm DC terminal 1 → lower copper foil 63 → upper bridge arm power tube (drain → source) → lower copper foil 63 → AC output terminal 3.

[0057] During the conduction of the lower bridge arm, the current path is: AC output terminal 3 → lower copper foil 63 → second copper layer of the second insulating substrate 4 → lower bridge arm power transistor (source → drain) → intermediate copper foil 62 → DC - lower bridge arm DC output terminal 2.

[0058] Because the upper bridge arm power transistor is located below the first opening of the lower copper foil 63, and the lower bridge arm power transistor is located below the second opening of the middle copper foil 62, and each power transistor 8 is vertically interconnected with each layer of copper foil through copper pillars, the area enclosed by the power circuit is greatly reduced, while the line width is increased. This effectively reduces the parasitic inductance of the circuit, avoids electrical stress damage to the power chip caused by voltage spikes, and fully leverages the high-frequency switching performance advantages of silicon carbide power chips.

[0059] Furthermore, the symmetrical arrangement of the upper and lower bridge arm power transistors helps to balance the loop parameters of the upper and lower bridge arms, further improving the operational stability and reliability of the power module. The thermally conductive copper layer at the bottom of the first insulating substrate 5 and the second insulating substrate 4 can efficiently conduct the heat generated by the power transistors to the external heat sink, ensuring the heat dissipation performance of the power module.

[0060] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A single-transistor embedded power module, characterized in that, include, Multiple power transistors, lower copper foil, middle copper foil, upper copper foil, first insulating substrate and second insulating substrate; The lower copper foil is connected to the upper bridge arm DC input terminal and AC output terminal, the middle copper foil is connected to the lower bridge arm DC output terminal, and the upper copper foil includes a control signal wiring layer, which is connected to the control signal of the power transistor. The lower copper foil has multiple first openings, and the middle copper foil has multiple second openings; Both the first insulating substrate and the second insulating substrate are composed of a first copper layer, a ceramic layer and a second copper layer stacked sequentially. The power single tube includes an upper bridge arm power single tube and a lower bridge arm power single tube; The drains of the plurality of upper bridge arm power transistors are respectively connected to the first copper layer of the first insulating substrate, and the drains of the plurality of lower bridge arm power transistors are respectively connected to the first copper layer of the second insulating substrate. The upper bridge arm power transistors and the lower bridge arm power transistors are arranged symmetrically. Each of the aforementioned power transistors includes a power chip, a connection layer, a conductive layer, and a molding compound; The upper bridge arm power transistor is disposed below the first opening, the first copper layer of the first insulating substrate is connected to the lower copper foil, the source of the upper bridge arm power transistor is connected to the lower copper foil, and the control electrode of the upper bridge arm power transistor is connected to the upper copper foil. The lower bridge arm power transistor is disposed below the second opening, the second copper layer of the second insulating substrate is connected to the lower copper foil, the source of the lower bridge arm power transistor is connected to the middle copper foil, and the control electrode of the lower bridge arm power transistor is connected to the upper copper foil.

2. The single-transistor embedded power module according to claim 1, characterized in that, The power transistors are connected to the first copper layer, the upper copper foil, the middle copper foil, and the lower copper foil of the first insulating substrate via copper pillars.

3. A single-transistor embedded power module according to claim 2, characterized in that, The copper pillar is cylindrical with a diameter of 0.1 mm to 0.3 mm.

4. A single-transistor embedded power module according to claim 1, characterized in that, A thermally conductive copper layer is provided on the bottom of the first insulating substrate and the bottom of the second insulating substrate, respectively.

5. A single-transistor embedded power module according to claim 4, characterized in that, The vertical distance between the first insulating substrate and the second insulating substrate is greater than 1.5 mm.

6. A single-transistor embedded power module according to claim 4, characterized in that, An insulating medium is filled between the upper copper foil and the thermally conductive copper layer.

7. A single-transistor embedded power module according to claim 6, characterized in that, The temperature resistance of the insulating medium is not lower than 200℃.

8. A single-transistor embedded power module according to claim 1, characterized in that, The connecting layer of the power transistor is made of silver, and the conductive layer is made of copper or molybdenum copper.

9. A single-transistor embedded power module according to claim 1, characterized in that, The lower copper foil, the middle copper foil, and the upper copper foil constitute a multilayer copper foil wiring layer of the PCB board.

10. A single-transistor embedded power module according to claim 9, characterized in that, The PCB board has an 8-layer structure.

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