A power semiconductor component

Abstract

The present invention relates to the technical field of power semiconductor devices, and particularly to a power semiconductor component. An embodiment of the present invention provides a power semiconductor component, which includes a semiconductor welding device and a heat sink connected by screws, wherein the semiconductor welding device includes a power semiconductor device and a ceramic-metal composite substrate welded together. Welding the power semiconductor device and the ceramic-metal composite substrate together facilitates the layer-by-layer alignment installation of the components in the power semiconductor component. In addition, the setting of the first metal layer and the second metal layer can make the ceramic substrate not easily break even under the condition of a relatively thin thickness. Therefore, the thermal resistance of the ceramic substrate can be reduced by reducing the thickness of the ceramic substrate, thereby improving the heat dissipation efficiency of the power semiconductor device.

Description

Technical Field

[0001] The present invention relates to the technical field of power semiconductor devices, and particularly to a power semiconductor component. Background Art

[0002] Power semiconductor devices, also known as power electronic devices, are mainly used for power conversion in power electronic circuits. When power semiconductor devices are working, they will generate heat due to power loss, and excessive temperature will shorten the service life of power semiconductor devices or even cause them to burn out.

[0003] To ensure that the heat generated by power semiconductor devices can be effectively dissipated, power semiconductor devices are usually directly fixed on radiators. Since the copper frame at the bottom of power semiconductor devices is charged, insulation requirements must also be met when connecting them to radiators. For example, an insulating ceramic substrate can be added between the power semiconductor device and the radiator, and thermal conductive silicone grease can be coated on both sides of the ceramic substrate. Then, the power semiconductor device can be fixed on the radiator by means of screw pressing bars or elastic sheet pressing.

[0004] In the process of implementing the present invention, the inventors found that in the prior art, due to the brittle material of the ceramic substrate, a relatively large thickness is usually required to ensure that it is not easily broken during the process of fixing the power semiconductor on the radiator. However, the greater the thickness of the ceramic substrate, the greater its own thermal resistance, which is not conducive to heat dissipation. Summary of the Invention

[0005] To overcome the problem of large thermal resistance caused by the large thickness of the power ceramic substrate, an embodiment of the present invention provides a power semiconductor component, in which metal layers are provided on both sides of the ceramic substrate, so that the ceramic substrate is not easily broken even when it is relatively thin, and thus the thermal resistance can be reduced by reducing the thickness of the ceramic substrate.

[0006] To solve the above technical problems, the embodiments of the present invention provide the following technical solutions:

[0007] An embodiment of the present invention provides a power semiconductor component, which includes a semiconductor welding device and a radiator connected by screws; wherein,

[0008] The semiconductor welding device includes a power semiconductor device and a ceramic-metal composite substrate welded to the power semiconductor device;

[0009] The ceramic-metal composite substrate includes a ceramic substrate and a first metal layer and a second metal layer respectively disposed on both surface sides of the ceramic substrate;

[0010] The first metal layer is located between the power semiconductor device and the ceramic substrate, and the second metal layer is located between the ceramic substrate and the radiator.

[0011] Optionally, a thermal grease layer is provided between the second metal layer and the heat sink.

[0012] Optionally, a soldering layer is provided between the power semiconductor device and the first metal layer;

[0013] The power semiconductor device is soldered to the first metal layer through the soldering layer.

[0014] Optionally, the soldering layer includes a printed solder paste layer or a preformed solder sheet layer.

[0015] Optionally, the edges of the first metal layer and the second metal layer are located inside the edges of the ceramic substrate.

[0016] Optionally, the first metal layer and the second metal layer are copper layers.

[0017] Optionally, a first through hole is formed in the power semiconductor device, a second through hole is formed in the ceramic-metal composite substrate, and the screw sequentially passes through the first through hole and the second through hole to be connected to the heat sink.

[0018] Optionally, the second through hole includes a third through hole, a fourth through hole, and a fifth through hole; wherein,

[0019] The third through hole is formed in the first metal layer, the fourth through hole is formed in the ceramic substrate, the fifth through hole is formed in the second metal layer, and the aperture of the fourth through hole is smaller than the apertures of the third through hole and the fifth through hole.

[0020] Optionally, the thickness of the ceramic substrate is 0.1 mm - 1.0 mm, and the thicknesses of the first metal layer and the second metal layer are both 0.1 mm - 1.0 mm.

[0021] Optionally, the total thickness of the first metal layer, the ceramic substrate layer, and the second metal layer is less than or equal to 2.0 mm.

[0022] The beneficial effects of the embodiments of the present invention are as follows: Different from the prior art, the embodiments of the present invention provide a power semiconductor module, which includes a semiconductor device and a heat sink connected by a screw, wherein the semiconductor device includes a power semiconductor device and a ceramic-metal composite substrate welded together. Welding the power semiconductor device and the ceramic-metal composite substrate together facilitates the layer-by-layer alignment installation of the components in the power semiconductor module. In addition, the setting of the first metal layer and the second metal layer can make the ceramic substrate not easily break even under the condition of a relatively thin thickness. Therefore, the thermal resistance of the ceramic substrate can be reduced by reducing the thickness of the ceramic substrate, thereby improving the heat dissipation efficiency of the power semiconductor device. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0024] Figure 1 is a schematic structural diagram of a power semiconductor component provided by an embodiment of the present invention;

[0025] Figure 2 is a schematic cross-sectional view of a ceramic-metal composite substrate provided by an embodiment of the present invention;

[0026] Figure 3 is a schematic top view of a ceramic-metal composite substrate provided by an embodiment of the present invention;

[0027] Figure 4 is a schematic bottom view of a ceramic-metal composite substrate provided by an embodiment of the present invention;

[0028] Figure 5 is a process flow chart of the assembly of a power semiconductor component provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] It should be noted that if there is no conflict, the various features in the embodiments of the present invention can be combined with each other, and all are within the protection scope of the present invention. In addition, although the functional modules are divided in the device schematic diagram and the logical order is shown in the flow chart, in some cases, the steps shown or described can be executed in a different module division from that in the device schematic diagram or a different order from that in the flow chart.

[0031] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in this specification in the description of the present invention are only for the purpose of describing specific embodiments and are not used to limit the present invention. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0032] Power semiconductor devices are one of the basic components of electronic products and have very wide applications in the power electronics industry. In order to enable power semiconductor devices to achieve good heat dissipation and insulation effects, it is usually necessary to set a heat dissipation and insulation medium between the power semiconductor device and the radiator, and then fix the power semiconductor device on the radiator through screws.

[0033] As one of the heat dissipation and insulation media between power semiconductor devices and radiators, ceramic substrates have the advantages of high temperature resistance, good electrical insulation performance, and relatively high thermal conductivity. However, due to the relatively large brittleness of the ceramic substrate itself, there are relatively high requirements for the flatness of the radiator and the ceramic substrate itself and the magnitude of the torque during assembly. Moreover, even if cracks appear in the ceramic substrate, it is very difficult to detect them, and there are significant drawbacks in application. Therefore, the present invention provides a power semiconductor component that uses a ceramic substrate with copper cladding on both sides as the heat dissipation and insulation medium, which can greatly reduce the thickness of the ceramic substrate while improving the overall strength of the ceramic substrate, effectively avoiding the situation of breakage and cracking of the ceramic substrate during the process of screw locking. For the convenience of understanding the present invention, the following will be described in conjunction with specific embodiments.

[0034] Please refer to Figure 1 , Figure 1 FIG. is a schematic structural diagram of a power semiconductor component provided by an embodiment of the present invention. As Figure 1 shown, the power semiconductor component 10 sequentially includes a screw 11 and a power semiconductor device 12, a ceramic substrate 13, and a radiator 14 connected by the screw 11; wherein, mutually insulated first metal layers 15 and second metal layers 16 are respectively arranged on both side surfaces of the ceramic substrate 13, the power semiconductor device 12 is fixedly connected to the first metal layer 15, and the radiator 14 is connected to the second metal layer 16.

[0035] The power semiconductor device 12 in the embodiment of the present invention may be a power semiconductor discrete device, for example, a power field effect transistor, an insulated gate bipolar transistor, and a diode, etc. The ceramic substrate 13 may be an alumina ceramic substrate or a nitride ceramic substrate. Alumina ceramics and nitride ceramics have relatively high thermal conductivity. Among them, the thermal conductivity of the alumina ceramic sheet is 20-28 W / m·K, and the thermal conductivity of the nitride ceramic sheet is 100-260 W / m·K. The ceramic substrate 13, the first metal layer 15, and the second metal layer 16 together form a ceramic-metal composite substrate. The ceramic composite metal substrate plays the role of heat conduction and insulation. The materials constituting the first metal layer 15 and the second metal layer 16 may be any suitable metals with good thermal conductivity, for example, metal copper. When the materials of the first metal layer 15 and the second metal layer 16 are metal copper, the ceramic-metal composite substrate is also called a ceramic substrate with copper cladding on both sides.

[0036] In some embodiments, the fixed connection between the power semiconductor device 12 and the first metal layer 15 is welding. The ceramic composite metal substrate is welded to the corresponding position of the power semiconductor device through a soldering process. Optionally, in some embodiments of the present invention, the power semiconductor device 12 is connected to the first metal layer 15 through a solder layer 17. Optionally, the solder layer 17 can be a printed solder paste layer or a preformed solder sheet layer. The welding method in the embodiments of the present invention includes reflow welding. The solder in the embodiments of the present invention can be a brazing alloy with a melting point of 138°C to 400°C. Generally, the thermal conductivity of the welding material is much greater than that of the thermal grease. Therefore, compared with the method of bonding with thermal grease, the welding method can greatly improve the heat dissipation efficiency of the power semiconductor module 10.

[0037] In the prior art, the ceramic substrate in the power semiconductor module usually needs to be coated with thermal grease on both sides, and then fixed between the power semiconductor device and the radiator by means of screw strip locking or elastic sheet pressing. It is necessary to install the ceramic substrate and the power semiconductor device layer by layer in alignment, which has high requirements for the positioning of each component and the design and processing of the tooling fixture. In the embodiments of the present invention, the power semiconductor device 12 and the ceramic metal composite substrate are formed into a module (i.e., a semiconductor welding device) by welding. When installing the power semiconductor module 10, the semiconductor welding device is directly installed on the radiator 14 by screws, without the need to install the ceramic substrate 14 and the power semiconductor device 12 layer by layer in alignment, thereby reducing the requirements for the installation operation.

[0038] The ceramic substrate 13, the first metal layer 15, and the second metal layer 16 in the embodiments of the present invention need to be closely combined under specific conditions. In some embodiments, the first metal layer 15 and the second metal layer 16 are bonded to the two side surfaces of the ceramic substrate 13. For example, after covering both sides of the ceramic substrate 13 with copper metal, it is heated in an environment with a high temperature of 1065 - 1085°C, so that the copper metal generates a eutectic melt due to high-temperature oxidation and diffusion with aluminum oxide or aluminum nitride, and the copper metal is bonded to the ceramic substrate to form a ceramic metal composite substrate. The bonding between the first metal layer 15 and the second metal layer 16 of the ceramic metal composite substrate formed by the bonding method and the ceramic substrate 13 is more firm.

[0039] In some embodiments, a first through hole (not shown in the figure) is opened on the power semiconductor device 12, and a second through hole is opened on the ceramic metal composite substrate. The screw 11 is sequentially connected to the radiator 14 through the first through hole and the second through hole. In some other embodiments, a screw insulator (not shown in the figure) is embedded in the radiator 14 for insulating the screw 11 and the radiator. The screw 11 in the embodiments of the present invention can be a combined machine thread screw or a self-tapping screw.

[0040] Please also refer to Figure 2 、Figure 3 and Figure 4 , Figure 2 、 Figure 3 and Figure 4 are the schematic cross-sectional, top, and bottom views of a ceramic-metal composite substrate provided by an embodiment of the present invention. As Figure 2 、 Figure 3 and Figure 4 shown, in some embodiments, the second through-hole further includes a third through-hole 151 formed in the first metal layer 15, a fourth through-hole 131 formed in the ceramic substrate 13, and a fifth through-hole 161 formed in the second metal layer, and the centers of the third through-hole 151, the fourth through-hole 131, and the fifth through-hole 161 are located on the same axis. Optionally, in some embodiments of the present invention, the third through-hole 151, the fourth through-hole 131, and the fifth through-hole 161 are all cylindrical through-holes.

[0041] In some embodiments, in order to ensure an insulating state between the first metal layer 15 and the second metal layer 16, the aperture of the fourth through-hole 131 is smaller than the apertures of the third through-hole 151 and the fifth through-hole 161; in addition, the area of the first metal layer 15 is smaller than the area of the upper surface of the ceramic substrate 13, and the area of the second metal layer 16 is smaller than the area of the lower surface of the ceramic substrate 13; moreover, the edges of the first metal layer 15 and the second metal layer 16 are located inside the edges of the ceramic substrate 13.

[0042] In an embodiment of the present invention, the total thickness of the ceramic-metal composite substrate is less than or equal to 2.0 mm. Among them, the thickness of the ceramic substrate 13 layer is 0.1 mm - 1.0 mm, and the thicknesses of the first metal layer 15 and the second metal layer 16 are both 0.1 mm - 1.0 mm. In the traditional design, the thickness of the ceramic substrate is generally above 0.6 mm and it is extremely easy to break when locking the screw. In the present invention, by using the ceramic-metal composite substrate instead of the traditional ceramic substrate, the thickness of the ceramic substrate can be reduced by at least half. Moreover, compared with the traditional ceramic substrate, the overall strength of the ceramic-metal composite substrate in the embodiment of the present invention is greatly improved. Therefore, when using screws to lock, the ceramic substrate 13 is not likely to break. At the same time, due to the reduction of the thickness of the ceramic substrate 13, the thermal resistance of the ceramic substrate 13 is further reduced.

[0043] In order to fill the air gap between the second metal layer 16 and the heat sink 14 to obtain a greater thermal conductivity, in some embodiments, a thermal grease layer 18 is provided between the second metal layer 16 and the heat sink 14. The function of the thermal grease layer 18 is to conduct the heat dissipated by the power semiconductor device 12 to the heat sink 14. In heat dissipation and heat conduction applications, even if two surfaces with very smooth surfaces come into contact with each other, there will be gaps. Since the air in these gaps is a poor conductor of heat, it will hinder the conduction of heat to the heat sink 14; while the thermal grease can fill these gaps to make the conduction of heat smoother and faster.

[0044] The thermal conductive silicone grease is a thermally conductive silicone grease-like composite made of organosilicone as the main raw material and adding materials with excellent heat resistance and thermal conductivity. The thermal conductive silicone grease not only has excellent electrical insulation but also has excellent thermal conductivity. At the same time, it also has a wide temperature range of use and has no corrosive effect on the contacted metal. When in use, as long as the thermal conductive silicone grease is applied to the contact surface of the second metal layer 16 or the radiator 14, the air gap between the contact surfaces can be eliminated.

[0045] Although the thermal conductive silicone grease can fill the air gap between the second metal layer 16 and the radiator 14 to obtain a greater thermal conductivity, its thermal conductivity is always lower than that of the metal radiator 14. If it is applied too thickly, it not only fails to improve the heat conduction but is also not conducive to the dissipation of heat. However, if it is applied too thinly, it cannot effectively fill the air gap between the radiator and the heat-generating component, and the effect of improving the thermal conductivity is not obvious enough. In some embodiments, in order to obtain a better heat conduction effect, the thickness of the thermal conductive silicone grease can be 0.08 mm - 0.12 mm.

[0046] The heat dissipation methods of the radiator in the embodiments of the present invention include natural cooling, forced air cooling, and water cooling. In some embodiments, the radiator 14 can be a heat dissipation substrate. The heat dissipation substrate can be a metal substrate with excellent thermal conductivity according to requirements, and its materials include but are not limited to copper-based, aluminum-based and other materials. In some other embodiments, one end of the radiator is an installation platform with installation holes, and the other end is a heat dissipation fin structure; the heat dissipation fins are composed of multiple parallel arranged sheet-like heat dissipation structures with a certain distance. The radiator absorbs heat through the heat dissipation substrate and dissipates the heat into the air through the heat dissipation fins.

[0047] In some other embodiments, the radiator 14 includes a planar substrate and at least one fan. The power semiconductor device 12 and the ceramic metal composite substrate can be placed on the planar substrate, and the multiple fans above or below the planar substrate suck air or blow air to take away the heat generated by the power semiconductor device. Optionally, the radiator 14 can also include a cooling plate containing an inner chamber. The power semiconductor device 12 and the ceramic metal composite substrate can be placed on the cooling plate, and the cooling water is pumped into the inner chamber of the cooling plate through the cooling water inlet to absorb the heat generated by the power semiconductor device.

[0048] Please refer to Figure 5 , Figure 5 which is a flowchart of the assembly process of a power semiconductor component provided by the embodiments of the present invention. As Figure 5 shown, in this embodiment, the assembly process of the power semiconductor component specifically includes the following steps:

[0049] S11. Weld the power semiconductor device 12 and the ceramic metal composite substrate to form a semiconductor welding device;

[0050] In this embodiment, a solder layer is filled between the bottom copper frame of the power semiconductor device 12 and the first metal layer 15 of the ceramic-metal composite substrate, and then the power semiconductor device 12 and the ceramic-metal composite substrate are aligned by a fixture. The power semiconductor device and the ceramic-metal composite substrate are soldered into a semiconductor soldering device by using a reflow soldering process.

[0051] S12. Thermal conductive silicone grease is filled between the semiconductor soldering device and the heat sink 14, and the semiconductor soldering device and the heat sink 14 are fixed by screws 11.

[0052] After thermal conductive silicone grease is filled between the second metal layer 12 and the heat sink 14, the semiconductor soldering device is attached to the heat sink 14, and the semiconductor soldering device and the heat sink are locked and assembled by using screws passing through the first through hole and the second through hole to obtain the power semiconductor assembly 10.

[0053] The embodiment of the present invention provides a power semiconductor assembly. The device includes a power semiconductor device, a ceramic substrate and a heat sink connected by screws; wherein, metal layers are provided on both sides of the ceramic substrate. The arrangement of the metal layers on both sides can make the ceramic substrate not easily break even under the condition of a relatively thin thickness. Therefore, the thickness of the ceramic substrate can be reduced to reduce the thermal resistance of the ceramic substrate, thereby improving the heat dissipation efficiency of the power semiconductor device. In the traditional design, the thickness of the ceramic substrate is generally more than 0.6 mm and it is extremely easy to break when locking the screws. In the present invention, by using a ceramic-metal composite substrate to replace the traditional ceramic substrate, the thickness of the ceramic substrate can be reduced by half, and the overall strength is greatly improved. The ceramic is not easy to break when locking the screws. At the same time, due to the reduction of the thickness of the ceramic layer, the thermal resistance of the ceramic substrate is further reduced.

[0054] 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 them; under the idea of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order, and there are many other changes in different aspects of the present invention as described above. For the sake of brevity, they are not provided in detail; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A power semiconductor component, characterized in that, The power semiconductor component includes a screw, a semiconductor welding device and a heat sink connected by the screw; wherein, the semiconductor welding device includes a power semiconductor discrete device and a ceramic-metal composite substrate welded to the power semiconductor discrete device; the ceramic-metal composite substrate includes a ceramic substrate and a first metal layer and a second metal layer respectively disposed on two side surfaces of the ceramic substrate; the first metal layer is located between the power semiconductor discrete device and the ceramic substrate, and the second metal layer is located between the ceramic substrate and the heat sink; a first through hole is formed in the power semiconductor discrete device, a second through hole is formed in the ceramic-metal composite substrate, and the screw is sequentially connected to the heat sink through the first through hole and the second through hole. The second through hole includes a third through hole, a fourth through hole and a fifth through hole. Wherein, the third through hole is formed in the first metal layer, the fourth through hole is formed in the ceramic substrate, and the fifth through hole is formed in the second metal layer. The aperture of the fourth through hole is smaller than the apertures of the third through hole and the fifth through hole.

2. The power semiconductor component according to claim 1, characterized in that A thermal grease layer is provided between the second metal layer and the heat sink.

3. The power semiconductor component according to claim 1, characterized in that, A welding layer is provided between the power semiconductor discrete device and the first metal layer; the power semiconductor discrete device is welded to the first metal layer through the welding layer.

4. The power semiconductor component according to claim 3, characterized in that, The welding layer includes a printed solder paste layer or a preformed solder sheet layer.

5. The power semiconductor component according to any one of claims 1 to 4, characterized in that, The edges of the first metal layer and the second metal layer are located inside the edges of the ceramic substrate.

6. The power semiconductor component according to claim 5, characterized in that, The first metal layer and the second metal layer are copper layers.

7. The power semiconductor component according to claim 1, characterized in that, The thickness of the ceramic substrate is 0.1 mm - 1.0 mm, and the thicknesses of the first metal layer and the second metal layer are both 0.1 mm - 1.0 mm.

8. The power semiconductor component according to claim 7, characterized in that, The thickness of the ceramic-metal composite substrate is less than or equal to 2.0 mm.

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