Power module terminal and power module

Abstract

The application discloses a power module terminal and a power module, and belongs to the field of power electronic power modules. The power module terminal comprises a main body part and a leading-out part extending outwards from the main body part. Two current introduction holes are arranged on the main body part, and a current leading-out hole is arranged on the leading-out part. A groove is arranged between the current leading-out hole and the outer edge of the main body part. The power module comprises a substrate, an upper bridge power chip set and a lower bridge power chip set arranged on the substrate, a positive copper layer and a negative copper layer, and further comprises a positive terminal and a negative terminal. The positive terminal and the negative terminal are the power module terminal described above, and are electrically connected to the positive copper layer and the negative copper layer through two current introduction holes respectively. The application solves the problems of large deformation in the welding process and large residual stress of the welding points after welding of the large-area terminal.

Description

Technical Field

[0001] This invention belongs to the field of power electronic power modules, and more specifically, relates to a power module terminal and a power module. Background Technology

[0002] Power semiconductors are a type of power electronic device. With the continuous development of power semiconductor technology, power module technology has also seen substantial improvements and rapid development. To improve the efficiency of power modules, higher switching frequencies are required. However, traditional power module layouts have high parasitic inductance, causing power chips to withstand high overvoltages during switching, increasing the risk of overvoltage breakdown. Therefore, power modules need to find ways to reduce parasitic inductance to maintain stable operation.

[0003] In the prior art, the parasitic inductance of the power terminals is reduced by increasing the area of ​​the terminals. However, large-area terminals have problems such as large deformation during the welding process, large residual stress of the solder joint after welding, and large deformation of the terminals and stress on the solder during temperature cycling, which affect the reliability of processing and operation. Summary of the Invention

[0004] To address the shortcomings and improvement needs of existing technologies, this invention provides a power module terminal and a power module, the purpose of which is to reduce the deformation and stress of the terminal at the current introduction point during temperature cycling.

[0005] To achieve the above objectives, according to one aspect of the present invention, a power module terminal is provided, comprising: a main body portion and an outwardly extending lead portion of the main body portion, wherein the main body portion is provided with two current inlet holes, the lead portion is provided with a current outlet hole, and a groove is formed between the current outlet hole and the outer edge of the main body portion.

[0006] Furthermore, the terminals on both sides of the groove have equal areas.

[0007] Furthermore, the groove is stepped, and the current lead-out hole serves as the starting point of the step.

[0008] Furthermore, the main body and the lead-out part are made of copper, copper plated with silver, or copper-molybdenum alloy.

[0009] According to another aspect of the present invention, a power module is provided, comprising a substrate, an upper-bridge power chip group and a lower-bridge power chip group disposed on the substrate, a positive copper layer and a negative copper layer, wherein the upper-bridge power chip group and the lower-bridge power chip group are electrically connected to the positive copper layer and the negative copper layer, respectively, characterized in that it further comprises: a positive terminal and a negative terminal, wherein the positive terminal and the negative terminal are both power module terminals as described in any one of the first aspects, and the positive terminal and the negative terminal are electrically connected to the positive copper layer and the negative copper layer through their respective two current inlet holes.

[0010] Furthermore, the positive terminal is stacked on top of the negative terminal.

[0011] Furthermore, the positive and negative terminals are made of copper, copper plated with silver, or a copper-molybdenum alloy.

[0012] In summary, the above-described technical solutions conceived in this invention can achieve the following beneficial effects:

[0013] (1) The power module terminal and power module of the present invention, by opening a groove between the lead-out part of the terminal and the outer edge of the main body, enables the large-area terminal to release deformation stress under high temperature cycling, thereby reducing the stress of the terminal at the current introduction point. Through simulation experiments, it is proved that the terminal of the present invention is set on the power module, which reduces the deformation at the welding point of the power module under high temperature and the residual stress of the solder after welding.

[0014] (2) Preferably, the terminal areas on both sides of the groove are equal, so that the current received by the two terminals is balanced.

[0015] (3) Preferably, the groove is stepped, which makes it easy to achieve equal terminal areas on both sides of the groove, so that the current received by the two terminals is balanced.

[0016] (4) Preferably, the terminal material is copper, copper plated with silver or copper-molybdenum alloy, which can further reduce parasitic inductance.

[0017] In summary, this invention solves the problems of large deformation during the welding process and large residual stress in the solder joints after welding of large-area terminals. Attached Figure Description

[0018] Figure 1 A schematic diagram of the power module terminal structure provided by the present invention.

[0019] Figure 2 This is a schematic diagram of a power module structure that does not include positive and negative terminals.

[0020] Figure 3 This is a schematic diagram of the structure of the power module terminals of the present invention when they are used as positive and negative terminals.

[0021] Figure 4 This is a schematic diagram of the power module structure provided by the present invention.

[0022] Figure 5 This is a diagram showing the stress distribution of the solder at the positive terminal welding point in the prior art.

[0023] Figure 6 This is a schematic diagram of the deformation at the positive terminal solder joint in the prior art.

[0024] Figure 7This is a stress distribution diagram of the solder at the positive terminal welding point in this invention.

[0025] Figure 8 This is a schematic diagram of the deformation at the positive terminal solder joint in this invention.

[0026] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0027] 20-Main body, 21-Lead-out part, 22, 25 are current inlet holes, 23-Current outlet hole, 24-Groove, 1-Substrate, 2-Positive copper layer, 3-Upper bridge chip connector, 4-Upper bridge power chipset, 5-Chip driver bonding wire, 6-Upper bridge arm chip driver circuit copper layer, 7-Positive terminal solder joint, 8-Negative copper layer, 9-Lower bridge power chipset, 10-Lower bridge chip connector, 11-Lower bridge arm chip driver circuit copper layer, 12-Negative terminal solder joint, 13-AC side copper layer, 14-AC side electrode terminal, 15-Positive terminal, 16-Negative terminal. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0029] like Figure 1 As shown, the present invention provides a power module terminal, which mainly includes: a main body 20 and an outwardly extending lead-out portion 21. The main body 20 has two current inlet holes 22 and 25 for introducing current through the solder joints of the power module. The lead-out portion 21 has a current outlet hole 23. A groove 24 is provided between the current outlet hole 23 and the outer edge of the main body. The groove penetrates the upper and lower surfaces of the main body and the lead-out portion, dividing the terminal into two parts.

[0030] By slotting large-area terminals, low parasitic inductance is ensured while reducing the large tensile stress introduced by large-area terminals to the solder joints. This reduces deformation at high temperatures and residual stress in the solder after soldering, and also reduces stress on the solder during temperature cycling.

[0031] Preferably, the terminal areas on both sides of the groove 24 are equal, that is, the terminal areas of the two parts divided by the groove are equal, so that the current received by the terminals of the two parts can be balanced.

[0032] Preferably, the groove 24 is stepped, starting from the current lead-out hole 23 and bending in a stepped shape to the outer edge of the main body, so as to make the current received by the terminals of the two parts equal.

[0033] Preferably, the main body 20 and the lead-out part 21 are made of copper, copper plated with silver, copper-molybdenum alloy, etc., to further reduce parasitic inductance.

[0034] like Figure 2 , Figure 3 As shown, the present invention provides a power module, comprising: a substrate 1, on which an upper-bridge power chip group 4 and a lower-bridge power chip group 9 are disposed; the drain of each chip in the upper-bridge power chip group 4 is connected to a positive copper layer 2, and the source of each chip is connected to an AC-side copper layer 13 via an upper-bridge chip connector 3; the drain of each chip in the lower-bridge power chip group 9 is connected to an AC-side copper layer 13, and the source of each chip is connected to a negative copper layer 8 via a lower-bridge chip connector 10; AC-side electrode terminals 14 are led out from the AC-side copper layer 13 of the module. Chip drive bonding wires 5 connect the gate and source of the chips in the upper-bridge power chip group 4 and the lower-bridge power chip group 9 to the corresponding drive circuit copper layers, respectively, for driving the chips. That is, the upper bridge power chip group 4 is connected to the upper bridge arm chip driver circuit copper layer 6 through the chip driver bonding line 5, and the lower bridge power chip group 9 is connected to the lower bridge arm chip driver circuit copper layer 11 through the chip driver bonding line 5; the positive terminal 15 is electrically connected to the positive copper layer 2 through the positive terminal solder point 7, and the negative terminal 16 is electrically connected to the negative copper layer 8 through the negative terminal solder point 12. The positive terminal 15 and the negative terminal 16 are the power module terminals provided by the present invention.

[0035] Specifically, the positive terminal 15 is electrically connected to the positive copper layer 2 through two current inlet holes 22 and 25 via the positive terminal solder joint 7; the negative terminal 16 is electrically connected to the negative copper layer 8 through two current inlet holes 22 and 25 via the negative terminal solder joint 12.

[0036] Furthermore, such as Figure 4 As shown, the positive terminal 15 is above the negative terminal 16, and adopts a stacked structure, which can further reduce the parasitic inductance introduced by the terminal.

[0037] This invention addresses the shortcomings of existing technologies where the positive and negative terminals lack slots. Simulations were conducted using the structure of this invention, with all simulations performed in a cyclic temperature environment ranging from 25℃ to 250℃, measuring the corresponding deformation and stress at the positive terminal. In this invention, stepped slots are formed on the terminals, and the positive and negative terminals employ a stacked structure. Simulation results are as follows: Figures 5-8 As shown.

[0038] like Figure 5The figure shows the stress distribution of the solder at the welding point when the positive terminal is not slotted in the prior art during a temperature cycle of 25℃-250℃. Through simulation experiments, it can be seen that the maximum stress at the solder at the positive terminal welding point is 61.645MPa.

[0039] like Figure 6 As shown, Figure 5 The corresponding solder joint deformation diagram shows that, through simulation experiments, the vertical component of the terminal solder joint deformation is 0.022mm.

[0040] like Figure 7 The figure shows the stress distribution of the solder at the welding point of the positive terminal of the present invention during the temperature cycling process of 25℃-250℃. Through simulation experiments, it can be seen that the maximum stress at the solder at the positive terminal welding point is 39.28MPa.

[0041] like Figure 8 As shown, Figure 7 The corresponding solder joint deformation diagram shows that, through simulation experiments, the vertical component of the terminal solder joint deformation is 0.0034 mm.

[0042] The simulation experiments described above demonstrate that the terminal structure of this invention can reduce deformation at high temperatures and residual stress in the solder after welding, as well as reduce stress on the solder during temperature cycling. Furthermore, by adjusting the experimental parameters, it was found that the maximum stress of the structure of this invention can be reduced by more than 50%.

[0043] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A power module terminal, characterized in that, include: The main body (20) and the lead-out portion (21) extending outward from the main body are provided with two current inlet holes (22, 25) on the main body (20) and a current outlet hole (23) on the lead-out portion (21). A groove (24) is provided between the current outlet hole (23) and the outer edge of the main body. The groove (24) passes through the current outlet hole (23) and the outer edge of the main body. The terminal areas on both sides of the groove (24) are equal.

2. The power module terminal according to claim 1, characterized in that, The groove (24) is stepped, and the current lead-out hole (23) serves as the starting point of the step.

3. The power module terminal according to claim 1, characterized in that, The main body (20) and the lead-out part (21) are made of copper, copper plated with silver or copper-molybdenum alloy.

4. A power module, comprising a substrate (1), an upper-bridge power chip assembly (4) and a lower-bridge power chip assembly (9) disposed on the substrate (1), a positive copper layer (2) and a negative copper layer (8), wherein the upper-bridge power chip assembly (4) and the lower-bridge power chip assembly (9) are electrically connected to the positive copper layer (2) and the negative copper layer (8) respectively, characterized in that, Also includes: Positive terminal (15) and negative terminal (16), wherein the positive terminal (15) and negative terminal (16) are power module terminals as described in any one of claims 1-3, and the positive terminal (15) and negative terminal (16) are electrically connected to the positive copper layer (2) and the negative copper layer (8) respectively through their respective two current inlet holes (22, 25).

5. The power module according to claim 4, characterized in that, The positive terminal (15) is stacked on top of the negative terminal (16).

6. The power module according to claim 4, characterized in that, The positive terminal (15) and the negative terminal (16) are made of copper, copper plated with silver, or copper-molybdenum alloy.

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