Power module capable of reducing internal stress

Abstract

The utility model belongs to a semiconductor power module, and provides a power module capable of reducing internal stress, which mainly comprises a heat dissipation bottom plate. The plurality of copper-clad ceramic substrates are arranged at intervals and are arranged on the heat dissipation bottom plate; the chip is arranged on the upper copper layer of the copper-clad ceramic substrate; the plastic shell has a preset thickness and is connected with the heat dissipation bottom plate, the plastic shell is arranged along the edge of the heat dissipation bottom plate, the plastic shell and the heat dissipation bottom plate form an encapsulation cavity, at least one first partition plate connected with the plastic shell is arranged in the plastic shell, the first partition plate is arranged along a preset gap between the two adjacent copper-clad ceramic substrates, and the first partition plate is connected with the heat dissipation bottom plate. The encapsulation cavity is divided into at least two mutually independent encapsulation areas, so that the encapsulation layer in each area is mutually independent, compared with a traditional whole encapsulation layer, the encapsulation layer has higher bending resistance, the encapsulation layer is prevented from cracking due to thermal stress or external mechanical force, and the integrity of electrical connection in the plastic shell is protected.

Description

Technical Field

[0001] The utility model belongs to a semiconductor power module, in particular to a power module with reduced internal stress. Background Art

[0002] Power semiconductor modules are widely used in industrial automation, new energy, electric vehicles and other fields. In new energy vehicles, the main function is to realize the conversion between DC and AC and complete the electric vehicle motor drive.

[0003] During the operation of the power module, the chip is a heat source, which will emit heat and transfer it to the packaging layer made of epoxy resin. In addition, vibrations often occur outside, so the epoxy resin will be subjected to thermal stress, mechanical stress, etc. When epoxy resin is encapsulated inside the power module, a solid body is formed. When subjected to force, excessive internal stress is likely to occur, causing cracking of the epoxy resin and electrical failure. Utility Model Content

[0004] The utility model provides a power module with reduced internal stress, which solves the problem in the above-mentioned background technology that when the power module is working, the heat generated by the chip is transferred to the packaging layer made of epoxy resin, the epoxy resin is slightly deformed by the thermal stress, resulting in the epoxy resin cracking and causing the internal electrical transmission failure.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] A power module with reduced internal stress, comprising:

[0007] Heat dissipation base plate;

[0008] A plurality of copper-clad ceramic substrates, wherein a preset spacing is provided between the plurality of copper-clad ceramic substrates, the copper-clad ceramic substrates comprising an upper copper layer, a ceramic layer and a lower copper layer, the upper copper layer being arranged on the upper end surface of the ceramic layer, the lower copper layer being arranged on the lower end surface of the ceramic layer, and the copper-clad ceramic substrate being arranged on the heat dissipation base plate through the lower copper layer;

[0009] A chip is arranged on the upper copper layer;

[0010] A plastic shell having a preset thickness, connected to the heat dissipation base plate, arranged along the edge of the heat dissipation base plate, and forming a potting cavity with the heat dissipation base plate, wherein at least one first partition connected to the plastic shell is arranged inside the plastic shell, and the first partition is arranged along a preset gap between two adjacent copper-clad ceramic substrates, so that the potting cavity is divided into at least two independent potting areas;

[0011] The potting layer is disposed in a plurality of independent potting areas for insulating and sealing the components on the copper-clad ceramic substrate;

[0012] The cover plate is detachably disposed on the plastic shell, and the cover plate shields and covers the potting cavity.

[0013] In some embodiments, the first partition includes two first ribs, and a first gap is provided between the two first ribs.

[0014] In some embodiments, the two first ribs of the first partition are integrally formed with the plastic shell.

[0015] In some embodiments, the plastic shell is provided with a second gap at the connection of the two first ribs, and the second gap has the same size as the first gap and corresponding positions, so that the plastic shell is divided into a plurality of independent modules corresponding to the plurality of potting areas.

[0016] In some embodiments, the plurality of independent potting areas correspond to the number of the plurality of copper-clad ceramic substrates.

[0017] In some embodiments, the upper top surface of the potting layer is not higher than the end surface of the first partition close to the cover plate.

[0018] In some embodiments, when the cover plate is disposed on the plastic shell, the cover plate abuts against the first rib.

[0019] In some embodiments, the cover plate is partitioned at the second gap of the plastic shell to form a plurality of relatively independent cover plate units, and each cover plate unit seals the corresponding potting area.

[0020] In some embodiments, it further includes a plurality of spaced heat dissipation columns, and the plurality of heat dissipation columns are disposed on the bottom surface of the heat dissipation bottom plate on the side away from the copper-clad ceramic substrate.

[0021] In some embodiments, the potting layer is formed by curing epoxy resin.

[0022] Compared with the prior art, the beneficial effects brought by the present invention are:

[0023] In this application, by providing a plurality of first partitions in the plastic shell, the first partitions are disposed along the preset gap between adjacent two copper-clad ceramic substrates, and the first partitions divide the potting cavity formed by the plastic shell and the heat dissipation bottom plate into a plurality of independent potting areas, each potting area corresponding to each copper-clad ceramic substrate, so that the potting layer in the potting cavity is divided into a plurality of smaller units, the bending strength of the potting layer is no longer continuous, and the thermal stress and external mechanical force are absorbed at the partition, avoiding the disconnection of the potting layer, thereby ensuring the stability of the electrical connection inside the power.

[0024] Additional aspects and advantages of the present application will be given in part in the following description, will become apparent from the following description, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 FIG. is a three-dimensional schematic diagram of the internal structure of a power module with reduced internal stress of the present utility model without a cover plate;

[0026] Figure 2 FIG. is a three-dimensional structural schematic diagram of one side of the heat dissipation bottom plate of a power module with reduced internal stress of the present utility model;

[0027] Figure 3 FIG. is a schematic diagram of the internal structure of a power module with reduced internal stress of the present utility model;

[0028] Figure 4 FIG. is a schematic diagram of the internal structure of another embodiment of a power module with reduced internal stress of the present utility model;

[0029] Figure 5 FIG. is the front view of a power module with reduced internal stress of the present utility model;

[0030] Figure 6 FIG. is the top view of a power module with reduced internal stress of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The following further describes the present application in detail with reference to specific drawings. In the description of this embodiment, unless otherwise specified, the orientation or positional relationship indicated by terms such as "left" and "right" is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the present application must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0032] As Figure 1 and Figure 2 shown, a power module with reduced internal stress provided by the present utility model mainly includes a heat dissipation bottom plate 2, a plurality of copper-clad ceramic substrates 3, a plastic shell 1, a potting layer 121, and a cover plate 4.

[0033] The heat dissipation bottom plate 2 is mainly used for heat dissipation, provides an installation position for the copper-clad ceramic substrates 3, and a plurality of copper-clad ceramic substrates 3 are arranged in an array on the heat dissipation bottom plate 2. At the same time, the heat dissipation bottom plate 2 is also used for installing and fixing with the plastic shell 1.

[0034] A plurality of copper-clad ceramic substrates 3 are arranged on the heat dissipation bottom plate 2 at preset intervals. The copper-clad ceramic substrate 3 includes an upper copper layer 31, a ceramic layer 32, and a lower copper layer 33. Specifically, as shown in Figure 3 the direction shown, the upper copper layer 31 is arranged on the upper end face of the ceramic layer 32, and the lower copper layer 33 is arranged on the lower end face of the ceramic layer 32. A welding layer is arranged on the lower copper layer 33, and the copper-clad ceramic substrate 3 is fixed on the heat dissipation bottom plate 2 through the welding layer. A chip 311 is also arranged on the upper copper layer 31;

[0035] The plastic shell 4 has a preset thickness. In this embodiment, the plastic shell 1 is a rectangular frame structure with a hollow structure in the middle. The edge of the plastic shell 1 matches the edge of the heat dissipation bottom plate 2. Through the combination of the plastic shell 1 and the heat dissipation bottom plate 2, a potting cavity 12 is formed in the plastic shell 1. Among them, it should be particularly noted that at least one first partition 11 is arranged in the potting cavity. The first partition 11 is arranged along the preset gap between adjacent two copper-clad ceramic substrates 3. The first partition 11 divides the potting cavity into at least two independent potting regions 12, and each potting region 12 corresponds to a copper-clad ceramic substrate 3;

[0036] The potting layer 121 is arranged in a plurality of independent potting regions 12 and is used to seal the components on the copper-clad ceramic substrate 3 to achieve electrical insulation. For example, the chip 311, metal bonding wires, parts of the wiring terminals, etc. The potting layer 121 is mainly formed by the solidification of a liquid epoxy resin material, and it presents a hard solid state after curing and has a relatively large elastic modulus. The cover plate 4 is detachably arranged on the plastic shell 1 to cover and seal the potting cavity formed by the plastic shell 1 and the heat dissipation bottom plate 2. When the potting layer 121 cools and forms, the cover plate 4 is covered to further seal and protect the objects in the potting cavity and perform dust-proof treatment. The size of the cover plate 4 matches the size of the plastic shell 1, and the edge of the cover plate 4 coincides with the edge of the plastic shell 1. Optionally, the number of the first partitions 11 can be two or three or more, and is specifically matched according to the number of the copper-clad ceramic substrates 3.

[0037] In this application, by arranging at least one partition 11 in the plastic shell 1, the potting cavity in the plastic shell 1 is divided into a plurality of independent potting regions 12, so that the potting layers 121 in each potting region 12 are independent of each other, dividing the traditional large potting layer 121 into a plurality of smaller modules, thereby making the bending of the potting layer 121 discontinuous and being absorbed at the first partition 11, avoiding the thermal stress caused by the heat generated by the chip 311 during operation and the external mechanical force from causing the potting layer 121 to crack, resulting in internal electrical failure of the power module.

[0038] In one embodiment, the first partition 11 includes two first ribs 111, and a first gap 112 is provided between the two first ribs 111. By providing the first gap 112 between the two first ribs 111, better absorption of the bending strength can be achieved, causing the bending strength to be concentrated on the heat dissipation bottom plate 2 at the first gap 112. The heat dissipation bottom plate 2 is generally a metal copper plate with high bending strength, thereby effectively preventing the potting layer 121 from deforming and cracking due to thermal stress or mechanical external force. Further, the two first ribs 111 are integrally formed with the plastic housing 1. On the one hand, the installation process of the first ribs 111 is simplified, and on the other hand, the connection strength between the two first ribs 111 and the plastic housing 1 is improved.

[0039] In one embodiment, the plastic housing 1 is provided with a second gap 13 at the connection of the two first ribs 111. The second gap 13 has the same size as the first gap 112 and corresponding positions, thereby dividing the plastic housing 1 into multiple independent modules corresponding to the multiple potting areas 12. Specifically, as Figure 4 and Figure 5 shown, the plastic housing 1 is divided into multiple segments, and each segment is fixedly connected to the corresponding first rib 111 to form multiple independent modules, that is, replacing the original integral form and dividing the plastic housing 1 into multiple smaller units. Further, the number of the multiple copper-clad ceramic substrates 3 matches the number of the multiple independent potting areas 12 to minimize the potting layer 121 in the potting area 12 where the copper-clad ceramic substrate 3 carrying the chip 311 is located, thereby increasing the bending resistance of the potting layer 121 in each potting area 12 and effectively preventing the potting layer 121 from cracking. Further, as Figure 6 shown, the cover plate 4 can also be correspondingly arranged into a structure partitioned at the second gap 13, and a third gap 42 is provided at the corresponding position of the cover plate 4, so that the cover plate 4 forms multiple independent cover plate units 41, and each cover plate unit 41 seals and protects each potting area 12. Optionally, as Figure 5 shown, in this structure, the cover plate 4 can also be arranged as a whole, that is, the end surface of the first rib 111 close to the cover plate 4 side is flush with the end surface of the plastic housing 1 close to the cover plate 4 side.

[0040] In one embodiment, as Figure 3 and Figure 4 shown, the upper top surface of the potting layer 121 is not higher than the end surface of the first partition 111 close to the cover plate 4 side, thereby effectively setting the potting layer 121 in each potting area 12 into an independent structure, improving its bending resistance, and preventing the upper top surface of the potting layer 121 from exceeding the end surface of the first partition 111 close to the cover plate 4 side and connecting into a whole block, reducing the partition effect.

[0041] In one embodiment, when the cover plate 4 is disposed on the plastic housing 1, the cover plate 4 abuts against the two first ribs 111 to ensure the sealing performance of the cover plate 4 for each sealing area 12, protecting the components and other parts within the sealing area 12.

[0042] In one embodiment, in order to better dissipate the heat generated by the chip 311 in a timely manner, a plurality of heat dissipation columns 21 are provided on the heat dissipation bottom plate 2. The plurality of heat dissipation columns 21 are arranged at intervals for the circulation of the cooling substance, and the cooling substance is a coolant or water at a lower temperature. By providing the heat dissipation columns 21, the contact surface between the cooling substance and the heat dissipation bottom plate 2 is increased, further improving the heat dissipation efficiency, so that the temperature generated by the chip 311 is discharged in a timely manner, avoiding large thermal stress generated at a high temperature and causing the potting layer 121 to deform and crack.

[0043] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made. These improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A power module with reduced internal stress, characterized in that Comprising: A heat dissipation bottom plate; A plurality of copper-clad ceramic substrates, with a preset spacing between the plurality of copper-clad ceramic substrates. The copper-clad ceramic substrate includes an upper copper layer, a ceramic layer, and a lower copper layer. The upper copper layer is disposed on the upper end surface of the ceramic layer, the lower copper layer is disposed on the lower end surface of the ceramic layer, and the copper-clad ceramic substrate is disposed on the heat dissipation bottom plate through the lower copper layer; A chip, disposed on the upper copper layer; A plastic shell, having a preset thickness, which is connected to the heat dissipation bottom plate. The plastic shell is disposed along the edge of the heat dissipation bottom plate. The plastic shell and the heat dissipation bottom plate form a potting cavity. Among them, at least one first partition connected to the plastic shell is disposed inside the plastic shell. The first partition is disposed along the preset gap between two adjacent copper-clad ceramic substrates, so that the potting cavity is divided into at least two independent potting regions; A potting layer, disposed in a plurality of independent potting regions, for insulating and sealing the components on the copper-clad ceramic substrate; A cover plate, detachably disposed on the plastic shell, and the cover plate covers the potting cavity; 2. A power module with reduced internal stress according to claim 1, characterized in that, The first partition includes two first ribs, and a first gap is provided between the two first ribs; 3. A power module with reduced internal stress according to claim 2, characterized in that, The two first ribs of the first partition are integrally formed with the plastic shell; 4. A power module with reduced internal stress according to claim 2, characterized in that, The plastic shell is provided with a second gap at the connection of the two first ribs. The second gap is the same size as and corresponds to the position of the first gap, so that the plastic shell is divided into a plurality of independent modules corresponding to the plurality of potting regions; 5. A power module with reduced internal stress according to claim 1, characterized in that, The plurality of independent potting regions correspond to the number of the plurality of copper-clad ceramic substrates; 6. A power module with reduced internal stress according to claim 1, characterized in that, The upper top surface of the potting layer is not higher than the end surface of the first partition close to the cover plate side; 7. A power module with reduced internal stress according to claim 4, characterized in that, When the cover plate is disposed on the plastic shell, the cover plate abuts against the first rib; 8. A power module having reduced internal stress according to claim 7, characterized in that, The cover plate is partitioned at the second gap of the plastic shell to form a plurality of relatively independent cover plate units, and each cover plate unit covers the corresponding potting region; 9. A power module with reduced internal stress according to any one of claims 1-8, characterized in that, It further includes a plurality of spaced heat dissipation columns, and the plurality of heat dissipation columns are disposed on the bottom surface of the heat dissipation bottom plate away from the copper-clad ceramic substrate side; 10. A power module with reduced internal stress according to claim 1, characterized in that, The potting layer is formed by the solidification of epoxy resin.

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