A laminated lead terminal and a power module using the same

Abstract

The present invention discloses a laminated lead terminal and a power module using the same. The laminated lead terminal includes a first lead terminal and a second lead terminal. The first lead terminal and the second lead terminal both include a main body, a connecting part is bent out at one end of the main body, a connecting part is provided with a connecting hole, a connecting arm is extended to both sides and away from the connecting part at the other end of the main body, and a welding foot is bent out at the end of the connecting arm; the connecting part of the second lead terminal is also provided with a transition hole, the connecting arm, the main body and the connecting part of the first lead terminal and the second lead terminal are laminated, and the connecting hole of the first lead terminal is provided above the transition hole. The lead terminal of the present application adopts a laminated structure, which reduces the parasitic inductance of the power module and reduces the oscillation of the switching voltage and current waveform.

Description

Technical Field

[0001] The present invention relates to the technical field of power semiconductor devices, and in particular to a laminated lead terminal and a power module using the lead terminal. Background Art

[0002] Power semiconductor switch chips, such as IGBT or SiC MOSFET chips, are packaged inside the power module to achieve high-speed switching control of large currents. However, since the packaging structure introduces parasitic inductance, when the switch chip is in operation, the parasitic inductance will cause voltage fluctuations, resulting in voltage overshoot or waveform oscillation, affecting the normal use of the power module. All power module packaging manufacturers are trying to reduce parasitic inductance as much as possible, and end users are also very concerned about this parameter, but there are not many effective ways to reduce parasitic inductance.

[0003] In recent years, as SiC MOSFET devices have become more mature, more stringent requirements have been placed on parasitic inductance. Only by reducing parasitic inductance can the high-frequency and high-efficiency characteristics of SiC devices be fully utilized. The traditional packaging structure has a large parasitic inductance and can no longer meet the needs of applications. It is urgent to develop a new type of power module with low parasitic inductance.

[0004] The information disclosed in this background technology section is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to those skilled in the art. Summary of the invention

[0005] The object of the present invention is to provide a laminated lead terminal and a power module using the lead terminal, by arranging the first lead terminal and the second lead terminal in parallel and opposite to each other over a large area, the connection between the lead terminal and the external busbar is facilitated; by arranging the laminated lead terminal inside the power module, the area of ​​the power freewheeling loop is reduced, thereby achieving the purpose of reducing parasitic inductance.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides a stacked lead terminal, comprising a first lead terminal and a second lead terminal. The first lead terminal and the second lead terminal both comprise a main body portion, a connecting portion is bent out at one end of the main body portion, the connecting portion is provided with a connecting hole, a connecting arm is extended out from the other end of the main body portion toward both sides and in a direction away from the connecting portion, a welding foot is bent out at the end of the connecting arm; the connecting portion of the second lead terminal is also provided with a transition hole, the connecting arm, the main body portion and the connecting portion of the first lead terminal and the second lead terminal are stacked, and the connecting hole of the first lead terminal is provided above the transition hole.

[0008] As a further technical solution, the welding feet of the first lead terminal and the second lead terminal are arranged back to back.

[0009] As a further technical solution, the size of the transition hole of the second lead terminal is larger than the size of the connection hole of the first lead terminal.

[0010] As a further technical solution, the length of the connecting portion of the second lead terminal is greater than the length of the connecting portion of the first lead terminal.

[0011] A power module also includes a base plate and a ceramic insulating substrate arranged above the base plate, the copper layer above the ceramic insulating substrate includes a separated positive copper layer and a negative copper layer, the welding foot of the first lead terminal is connected to the positive copper layer, and the welding foot of the second lead terminal is connected to the negative copper layer.

[0012] As a further technical solution, it also includes a molded shell, which is arranged above the base plate, and the first lead terminal and the second lead terminal are injection molded inside the molded shell. Nut countersunk holes are arranged at the positions of the connecting holes of the first lead terminal and the second lead terminal, and the upper and lower sides of the nut countersunk holes are hollow structures.

[0013] As a further technical solution, it also includes an output copper layer, a transition copper layer, an upper bridge arm gate copper layer, and a lower bridge arm gate copper layer. The upper bridge arm chip is arranged on the positive copper layer, and the lower bridge arm chip is arranged on the transition copper layer.

[0014] As a further technical solution, the upper bridge arm chip and the lower bridge arm chip are one or more of an IGBT chip, a MOSFET chip, an FRD chip, and an SBD chip. When the upper bridge arm chip and the lower bridge arm chip include an IGBT chip or a MOSFET chip, the gate of the upper bridge arm IGBT chip or the MOSFET chip is connected to the upper bridge arm gate copper layer through a bonding wire, and the gate of the lower bridge arm IGBT chip or the MOSFET chip is connected to the lower bridge arm gate copper layer through a bonding wire.

[0015] As a further technical solution, the upper bridge arm chip is connected to the output copper layer and the transition copper layer through a connecting copper bridge, and the lower bridge arm chip is connected to the negative electrode copper layer through a connecting copper bridge.

[0016] As a further technical solution, flexible silicone is arranged inside the molded shell, and the flexible silicone covers the upper bridge arm chip, the lower bridge arm chip, and the bonding wires; epoxy resin is injected into the hollow part of the molded shell, and the epoxy resin covers the flexible silicone.

[0017] By adopting the above technical solution, the present invention has the following beneficial effects:

[0018] 1. The power lead terminal adopts a laminated structure to reduce the parasitic inductance of the power module and reduce the oscillation of the switching voltage and current waveform.

[0019] 2. The opening on the top of the shell allows the ultrasonic welding process to be used when the power lead terminals are injection molded inside the shell, thereby improving the reliability of the power module.

[0020] 3. The power terminal is easy to install and has a simple structure.

[0021] 4. The lead terminal is firmly connected to the shell, with high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 It is a schematic diagram of the structure and combination relationship of the laminated lead terminal of the present invention;

[0024] Figure 2 This is an application example of the laminated lead terminal of the present invention in a power module;

[0025] Figure 3 It is a schematic diagram of the internal structure of the power module of the present invention;

[0026] Figure 4 It is a schematic diagram of the internal chip layout of the module of the present invention;

[0027] Figure 5 This is a schematic diagram of the modular molded housing structure of the present invention;

[0028] Figure 6 This is a schematic diagram of the position of the ultrasonic welding head of the lead terminal of the present invention;

[0029] Figure 7 It is a schematic diagram of the connection between the external busbar and the power lead terminal of the present invention. DETAILED DESCRIPTION

[0030] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention 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, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0032] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0034] like Figure 1 As shown, the present invention provides a laminated lead terminal, including a first lead terminal 1 and a second lead terminal 2; the first lead terminal 1 and the second lead terminal 2 both include a main body 3, a connecting part 4 is bent to one side at the upper end of the main body 3, and the connecting part 4 is provided with a connecting hole 5; the other end of the main body 3 extends a cantilever extending to both sides in the direction of the main body 3, the width of the cantilever is smaller than the width of the main body, the end of the cantilever extends in a direction away from the connecting part 4, and together with the cantilever, a connecting arm 6 is formed, and a welding foot 7 is bent at the end of the connecting arm 6, wherein: the welding foot of the first lead terminal 1 extends in a direction away from the connecting part, and the welding foot of the second lead terminal 2 extends in the direction of the connecting part. The welding foot of the first lead terminal is arranged opposite to the welding foot of the second lead terminal.

[0035] The connecting portion of the second lead terminal 2 is further provided with a transition hole 8 , the size of which is larger than the size of the connecting hole of the first lead terminal, and the transition hole 8 may be circular or elliptical.

[0036] The connection part 4 is perpendicular to the main body part 3 at 90°, the welding foot 7 is perpendicular to the main body part 3 at 90°, and the connection part 4 is parallel to the welding foot 7.

[0037] The connecting arm 6, the main body 3 and the connecting part 4 of the first lead terminal 1 and the second lead terminal 2 are stacked, and the connecting hole of the first lead terminal is arranged above the transition hole 8 of the second lead terminal, and the length of the connecting part of the second lead terminal is greater than that of the connecting part of the first lead terminal.

[0038] The stacked lead terminals are set inside the power module to form Figure 2 The power module shown in the figure further comprises a base plate 9, a molded shell 10, epoxy resin 11, an output lead terminal 12, and a drive lead terminal 13. The molded shell 10 is arranged above the base plate 9, and four hollow areas of the molded shell 10 are filled with epoxy resin 11.

[0039] The driving lead terminal 13 passes through the epoxy resin 11 , and the first lead terminal 1 , the second lead terminal 2 , and the output lead terminal 12 pass through the molded housing 10 , wherein the output lead terminal 12 is located at the other end of the module.

[0040] like Figure 3 and Figure 4 As shown, the internal structure of the power module is shown. A ceramic insulating substrate 14 is arranged above the base plate 9. The copper layer above the ceramic insulating substrate 14 includes a separated positive copper layer 15, a negative copper layer 16, an output copper layer 17, a transition copper layer 18, an upper bridge arm gate copper layer 19, and a lower bridge arm gate copper layer 20. The welding foot of the first lead terminal 1 is soldered or sintered above the positive copper layer 15, and the welding foot of the second lead terminal 2 is soldered or sintered above the negative copper layer 16.

[0041] The upper bridge arm chip 21 is arranged above the transition copper layer 18, and the lower bridge arm chip 22 is arranged above the positive copper layer. The upper bridge arm chip 21 and the lower bridge arm chip 22 are one or more of an IGBT chip, a MOSFET chip, an FRD chip, and an SBD chip. When the upper bridge arm chip and the lower bridge arm chip include an IGBT chip or a MOSFET chip, the gate of the upper bridge arm IGBT chip or the MOSFET chip is connected to the upper bridge arm gate copper layer through a bonding wire 23, and the gate of the lower bridge arm IGBT chip or the MOSFET chip is connected to the lower bridge arm gate copper layer through a bonding wire 23.

[0042] When the upper bridge arm chip 21 and the lower bridge arm chip 22 include an IGBT chip or a MOSFET chip, the collector of the IGBT chip and the drain of the MOSFET chip are brazed or sintered on the positive copper layer 15 and the transition copper layer 18. The emitter of the IGBT chip and the source of the MOSFET chip are brazed or sintered with a connecting copper bridge 24.

[0043] The upper bridge arm chip 21 is connected to the output copper layer 17 and the transition copper layer 18 through the connecting copper bridge 24, and the lower bridge arm chip 22 is connected to the negative copper layer 16 through the connecting copper bridge 24. The upper bridge arm chip 21 can also be connected to the output copper layer 17 and the transition copper layer 18 through bonding wires, aluminum strips, etc., and the lower bridge arm chip 22 can also be connected to the negative copper layer 16 through bonding wires, aluminum strips, etc.

[0044] like Figure 5 The figure shows a schematic diagram of the molded shell structure of the module. The molded shell 10 is provided with open holes around it, which cooperate with the bottom plate to realize the mechanical connection between the module and the radiator. Countersunk holes 25 for placing nuts are provided below the connection holes of the first lead terminal, the second lead terminal, and the output lead terminal. The corresponding position of the first lead terminal on the molded shell is higher than the position of the second lead terminal on the shell. A shell is provided between the connecting parts of the first lead terminal and the second lead terminal. The material of the shell is generally engineering plastics such as PBT, PPS, and PPA.

[0045] The top of the molded shell is provided with four separated hollow parts, the driving terminals pass through the hollow parts, and silicone gel is also poured through the hollow parts. The flexible silicone gel covers the upper bridge arm chip, the lower bridge arm chip, and the bonding wires; epoxy resin is injected into the hollow parts of the molded shell, and the epoxy resin covers the flexible silicone gel.

[0046] The connection between the lead terminal and the ceramic insulating substrate in the power module of the present invention can be made by brazing or sintering, or by ultrasonic metal welding. Ultrasonic metal welding has higher reliability and higher connection strength. In order to meet the needs of ultrasonic metal welding technology, a corresponding hollow position 26 is set on the top of the shell. This position can be used to fill silicone gel and also allows the ultrasonic metal welding welding head to reach the welding position smoothly. Figure 6 In addition, the first lead terminal, the second lead terminal, and part of the output lead terminal are arranged inside the molded shell, considering that the lead terminal will not transmit mechanical stress to the welding part with the vibration of the busbar during use, and the reliability of the module can also be improved.

[0047] like Figure 7 As shown, it is a schematic diagram of the connection between the module and the external busbar, the first busbar 27 and the second busbar 28 are connected to the first lead terminal 1 and the second lead terminal 2 respectively, and the output busbar 29 is connected to the output lead terminal 12; and the first busbar 27 and the second busbar 28 can also be arranged in a stacked structure, which can fully reduce the parasitic inductance of the application system and improve the conversion efficiency.

[0048] 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 replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A laminated lead terminal, comprising a first lead terminal and a second lead terminal, wherein the first lead terminal and the second lead terminal both comprise a main body, a connecting portion is bent out at one end of the main body, the connecting portion is provided with a connecting hole, a connecting arm is extended out from the other end of the main body toward both sides and in a direction away from the connecting portion, and a welding foot is bent out at the end of the connecting arm; characterized in that: The connecting part of the second lead terminal is also provided with a transition hole, the connecting arms, the main body and the connecting part of the first lead terminal and the second lead terminal are stacked, and the connecting hole of the first lead terminal is arranged above the transition hole; the welding feet of the first lead terminal and the second lead terminal are arranged back to back; the size of the transition hole of the second lead terminal is larger than the size of the connecting hole of the first lead terminal; the length of the connecting part of the second lead terminal is larger than the length of the connecting part of the first lead terminal.

2. A power module using the laminated lead terminal according to claim 1, characterized in that: It also includes a base plate and a ceramic insulating substrate arranged above the base plate, the copper layer above the ceramic insulating substrate includes a separated positive copper layer and a negative copper layer, the welding foot of the first lead terminal is connected to the positive copper layer, and the welding foot of the second lead terminal is connected to the negative copper layer.

3. The power module according to claim 2, characterized in that: It also includes a molded shell, which is arranged above the base plate, the first lead terminal and the second lead terminal are injection molded inside the molded shell, and nut countersunk holes are arranged at the positions of the connecting holes of the first lead terminal and the second lead terminal, and the upper and lower sides of the nut countersunk holes are hollow structures.

4. The power module according to claim 3, characterized in that: It also includes an output copper layer, a transition copper layer, an upper bridge arm gate copper layer, and a lower bridge arm gate copper layer. The upper bridge arm chip is arranged on the positive copper layer, and the lower bridge arm chip is arranged on the transition copper layer.

5. The power module according to claim 4, characterized in that: The upper bridge arm chip and the lower bridge arm chip are one or more of an IGBT chip, a MOSFET chip, an FRD chip, and an SBD chip. When the upper bridge arm chip and the lower bridge arm chip include an IGBT chip or a MOSFET chip, the gate of the upper bridge arm IGBT chip or the MOSFET chip is connected to the upper bridge arm gate copper layer through a bonding wire, and the gate of the lower bridge arm IGBT chip or the MOSFET chip is connected to the lower bridge arm gate copper layer through a bonding wire.

6. The power module according to claim 5, characterized in that: The upper bridge arm chip is connected to the output copper layer and the transition copper layer through a connecting copper bridge, and the lower bridge arm chip is connected to the negative electrode copper layer through a connecting copper bridge.

7. The power module according to claim 6, characterized in that: Flexible silicone is arranged inside the molded shell, and the flexible silicone covers the upper bridge arm chip, the lower bridge arm chip, and the bonding wires; epoxy resin is injected into the hollow part of the molded shell, and the epoxy resin covers the flexible silicone.

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