IGBT substrate and preparation method thereof

Abstract

The invention discloses an IGBT substrate and a preparation method thereof, and belongs to the technical field of semiconductor devices.The IGBT substrate comprises a substrate body, the first side of the substrate body is a welding face, the opposite second side of the substrate body is a heat dissipation face, and the substrate body comprises an aluminum silicon carbide layer, an aluminum alloy layer and a nickel plating layer; aluminum alloy layers are arranged on the two opposite sides of the aluminum silicon carbide layer, nickel plating layers are arranged on the outer sides of the aluminum alloy layers on the two sides, the nickel plating layer on one side is of a plane structure and used for forming a welding face, the nickel plating layer on the other side is of an arc-shaped structure and used for forming a heat dissipation face, and a latticed solder resisting strip is arranged on the welding face. A welding area is formed in the grid of the solder resisting strip in an enclosing mode. The surface of the substrate body is coated with a layer of aluminum alloy to improve the plating performance of aluminum silicon carbide, and the surface of the substrate body is plated with nickel to improve the welding performance and the salt spray performance of the substrate.

Description

Technical Field

[0001] The present application relates to the field of semiconductor device technology, and in particular, to an IGBT substrate and a method for preparing the same. Furthermore, the present application also relates to a method for preparing the above-mentioned IGBT substrate. Background Art

[0002] The information provided in this section is for the purpose of generally presenting the background of the present application. To the extent described in this section, the work of the presently named inventors and aspects of the description that may not constitute prior art at the time of filing are neither explicitly nor implicitly admitted to be prior art to the present application.

[0003] IGBTs (Insulated Gate Bipolar Transistors) are fully controlled, voltage-driven, composite power semiconductor devices composed of BJTs (Bipolar Junction Transistors) and MOSs (Insulated Gate Field Effect Transistors). As a key component in power conversion, IGBT modules are widely used in high-speed rail, subways, wind power, and other fields.

[0004] High-power IGBT modules generate significant internal heat during operation, placing higher demands on the substrate's heat dissipation and expansion coefficient. Aluminum-silicon carbide composites are widely used as substrates for high-power IGBT module packaging due to their high thermal conductivity, high strength, and low expansion coefficient (matching the chip's expansion coefficient).

[0005] Traditional aluminum silicon carbide substrates have poor soldering performance, and both plating and salt spray resistance need further improvement. Furthermore, traditional aluminum silicon carbide substrates typically use screen printing ink on the substrate surface to prevent solder paste overflow during chip soldering. However, this ink solder mask printing method has poor dimensional accuracy, a complex printing process with high environmental requirements and demanding process control, making it unsuitable for large-scale, efficient production. Summary of the Invention

[0006] In view of at least one of the above technical problems, the present application provides an IGBT substrate, which can improve the plating performance of aluminum silicon carbide by coating a layer of aluminum alloy on the surface of the substrate body, and improve the welding performance and salt spray performance of the substrate by plating nickel on the surface of the substrate body.

[0007] At the same time, the present application also provides a preparation method for the above-mentioned IGBT substrate.

[0008] According to one aspect of the present application, an IGBT substrate is provided, comprising a substrate body, the substrate body comprising an aluminum silicon carbide layer, an aluminum alloy layer being provided on opposite sides of the aluminum silicon carbide layer, a nickel-plated layer being provided on the outer side of the aluminum alloy layer, the nickel-plated layer on one side of the substrate body being a planar structure and being used to constitute a welding surface, the nickel-plated layer on the other side of the substrate body being an arc-shaped structure and being used to constitute a heat dissipation surface, a grid-shaped solder resist being provided on the welding surface, the grid of the solder resist being enclosed within a welding area, the solder resist being used to prevent solder paste from flowing when the IGBT substrate is soldered to a chip through the welding area.

[0009] In some embodiments of the present application, the side of the aluminum silicon carbide layer close to the heat dissipation surface is a curved surface structure, and the aluminum alloy layer close to the heat dissipation surface is an arc-shaped structure.

[0010] According to another aspect of the present application, a method for preparing an IGBT substrate is provided, which is applied to the above-mentioned IGBT substrate. The method for preparing the IGBT substrate comprises the following steps:

[0011] S100: Selecting two silicon carbide particles of different particle sizes and mixing them evenly, adding an aqueous solution of aluminum dihydrogen phosphate at 1-2% of the total mass of the silicon carbide particles and water at 4% of the total mass of the silicon carbide particles, mixing evenly, drying and granulating to obtain an initial powder, pressing the initial powder into a green billet through a mold, and curing the green billet to obtain a silicon carbide preform billet;

[0012] S200: Processing the silicon carbide preform blank into a silicon carbide preform by CNC;

[0013] S300: placing the silicon carbide preform into a mold and preheating the mold together with the mold, pouring molten aluminum alloy after reaching the preheating temperature, and performing vacuum pressure infiltration to obtain an aluminum silicon carbide blank;

[0014] S400: CNC machining the aluminum silicon carbide blank to a preset size to obtain an aluminum silicon carbide substrate material;

[0015] S500: polishing and sandblasting the aluminum silicon carbide substrate material, and then performing surface nickel plating treatment to obtain the aluminum silicon carbide substrate;

[0016] S600: The aluminum silicon carbide substrate is filled and etched by laser to form a grid-shaped solder mask on the welding surface.

[0017] In some embodiments of the present application, step S100 specifically includes: uniformly mixing first silicon carbide particles and second silicon carbide particles, wherein the particle size of the first silicon carbide particles is 80-100 μm, the particle size of the second silicon carbide particles is 8-12 μm, and the ratio of the first silicon carbide particles to the second silicon carbide particles is 8:2; then adding 1-2% of the total mass of the silicon carbide particles to an aqueous solution of aluminum dihydrogen phosphate and 4% of the total mass of the silicon carbide particles to water, mixing evenly, and then drying and granulating to obtain an initial powder, and the tap density of the initial powder is not less than 2.2 g / cm 3 The initial powder is pressed into a green billet by a mold under a pressure of 200 MPa, and the green billet is solidified at a temperature of 750° C. to obtain a silicon carbide preform blank.

[0018] In some embodiments of the present application, the porosity of the silicon carbide preform reaches 25%-31%, so that the thermal expansion coefficient of the aluminum silicon carbide substrate obtained by compounding the silicon carbide preform with the aluminum alloy reaches a preset value.

[0019] In some embodiments of the present application, the thermal expansion coefficient of the aluminum silicon carbide substrate is preset to 6-8 ppm / K, 50-150°C.

[0020] In some embodiments of the present application, when the silicon carbide preform is placed in the mold in step S300, a gap of 0.05-0.35 mm is left between the silicon carbide preform and the side wall of the mold, and then the preform is preheated to a preheating temperature of 580-650°C together with the mold, and the temperature of the poured molten aluminum alloy is 700-760°C.

[0021] In some embodiments of the present application, in step S400, one side of the aluminum silicon carbide blank is processed into a flat surface by CNC, and the opposite side is processed into a curved surface, and the curvature radius of the curved surface ranges from 11000 to 17000.

[0022] In some embodiments of the present application, in step S500 , a layer of nickel with a thickness of 5-20 μm is plated on the surface of the aluminum silicon carbide substrate material.

[0023] In some embodiments of the present application, in step S600, the power of the laser is 30-100 W, the frequency is 50 Hz, and the scanning speed is 600 mm / s; the laser etching depth is 1-4 μm, and the etching width is 1-20 mm.

[0024] This application has the following beneficial effects:

[0025] The present application discloses an IGBT substrate comprising an aluminum silicon carbide layer, an aluminum alloy layer, and a nickel-plated layer. The aluminum alloy layer is disposed on opposite sides of the aluminum silicon carbide layer, and a nickel-plated layer is disposed on the outside of the aluminum alloy layer on both sides. The aluminum silicon carbide composite material achieves high thermal conductivity, high strength, and a lower expansion coefficient relative to the external chip. The aluminum alloy coating on the aluminum silicon carbide improves the plating performance of the aluminum silicon carbide layer. The nickel-plated layer disposed on the outside of the aluminum alloy layer on both sides effectively improves the welding performance and salt spray performance of the IGBT substrate, resolving the problem of poor welding performance of both aluminum silicon carbide and aluminum alloy. The nickel-plated layer on one side is a planar structure and serves to form a welding surface, while the nickel-plated layer on the other side is an arc-shaped structure and serves to form a heat dissipation surface. The arc-shaped heat dissipation surface achieves better heat dissipation. The grid-shaped solder mask on the welding surface can be enclosed by the grid of the solder mask to form multiple welding areas. The solder mask prevents the solder paste from flowing easily when the IGBT substrate is soldered to the chip, thereby achieving the effect of solder resistance and ensuring smooth and high-quality chip soldering.

[0026] The preparation method of the IGBT substrate of the present application also has the above-mentioned beneficial effects. It also includes the following steps: mixing silicon carbide particles of different particle sizes with an aqueous solution of aluminum dihydrogen phosphate and water to form an initial powder, using the initial powder to press and form a blank through a mold, and then solidifying the blank to obtain a silicon carbide preform blank. The silicon carbide preform blank can be processed by CNC to obtain a silicon carbide preform, and the silicon carbide preform is preheated in the mold and then poured with molten aluminum alloy and subjected to vacuum pressure infiltration to obtain an aluminum silicon carbide blank. The aluminum silicon carbide blank is processed by CNC, polished, sandblasted, and then nickel-plated on the surface to obtain an aluminum silicon carbide base. Finally, a grid-like solder mask is formed on the welding surface by laser filling and etching, thereby completing the preparation of the entire substrate. The overall preparation process is very clear and efficient. Compared with ink solder mask, laser filling and etching of the solder mask has a simple process, high dimensional accuracy, and high production efficiency. It improves the solder mask capability while solving the problem of the influence of burrs on the edge of the engraved line on welding.

[0027] Of course, any product implementing this application does not necessarily need to achieve all of the advantages described above. In addition to the purposes, features, and advantages described above, this application also has other purposes, features, and advantages. This application will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of this application. The exemplary embodiments and descriptions of this application are intended to explain this application and do not constitute an improper limitation on this application. In the accompanying drawings:

[0029] Figure 1 This is a schematic diagram of the overall structure of the IGBT substrate in a preferred embodiment of the present application;

[0030] Figure 2 Schematic diagram of the structure of each layer of the IGBT substrate of the preferred embodiment of the present application;

[0031] Figure 3 It is a structural schematic diagram of the welding surface of the IGBT substrate of the preferred embodiment of the present application.

[0032] Legend: 100, substrate body; 101, welding surface; 102, heat dissipation surface; 103, solder mask; 104, welding area; 1, aluminum silicon carbide layer; 11, first curved surface; 2, aluminum alloy layer; 21, second curved surface; 3, nickel plating layer; 31, third curved surface. DETAILED DESCRIPTION

[0033] The embodiments of the present application are described in detail below with reference to the accompanying drawings, but the present application can be implemented in a variety of different ways defined and covered below.

[0034] Figure 1 This is a schematic diagram of the overall structure of the IGBT substrate in a preferred embodiment of the present application; Figure 2 Schematic diagram of the structure of each layer of the IGBT substrate of the preferred embodiment of the present application; Figure 3 It is a structural schematic diagram of the welding surface of the IGBT substrate of the preferred embodiment of the present application.

[0035] An IGBT substrate includes a substrate body 100, which includes an aluminum silicon carbide layer 1. An aluminum alloy layer 2 is provided on opposite sides of the aluminum silicon carbide layer 1. A nickel-plated layer 3 is provided on the outer side of the aluminum alloy layer 2. The nickel-plated layer 3 on one side of the substrate body 100 has a planar structure and is used to form a welding surface 101. The nickel-plated layer 3 on the other side of the substrate body 100 has an arc-shaped structure and is used to form a heat dissipation surface 102. A grid-shaped solder resist tape 103 is provided on the welding surface 101. The grid of the solder resist tape 103 encloses a welding area 104. The solder resist tape 103 is used to prevent solder paste from flowing when the IGBT substrate is soldered to a chip through the welding area 104.

[0036] The "solder resist 103" here means a mesh structure that prevents the solder paste from flowing when the IGBT substrate is soldered to the chip through the welding area 104. Preferably, the solder resist 103 is filled and etched by laser, and is etched with a small depth (1-4 μm deep) and a width range of 1-20 mm to achieve the effect of no burrs on the etching edge and avoid breakdown of the nickel-plated layer 3.

[0037] It should be noted that by providing an arc-shaped structure on one side of the nickel-plated layer 3 to form the heat dissipation surface 102, the heat dissipation effect of the heat dissipation surface 102 can be effectively improved. Preferably, the heat dissipation surface 102 is an outwardly convex curved surface structure, and its curvature radius R is 11000-17000. Due to the difference in the expansion coefficient of the chip and the aluminum silicon carbide substrate when soldering the chip, the curvature of the aluminum silicon carbide substrate will become smaller after soldering the chip. Therefore, if the processing curvature radius of the heat dissipation surface 102 is too large, the original curvature of the aluminum silicon carbide substrate will be too small, and the curvature of the aluminum silicon carbide substrate may become negative after the chip is soldered, that is, the heat dissipation surface will become an inward concave surface, which is not conducive to the heat dissipation of the IGBT module; if the processing curvature radius is too small, the original curvature of the aluminum silicon carbide substrate will be too large, and the curvature of the aluminum silicon carbide substrate will be too large after the chip is soldered. The torque will be too large when installing the IGBT module, causing risks such as cracking of the aluminum silicon carbide substrate mounting hole.

[0038] The present application discloses an IGBT substrate comprising an aluminum silicon carbide layer 1, an aluminum alloy layer 2, and a nickel-plated layer 3. The aluminum alloy layer 2 is disposed on opposite sides of the aluminum silicon carbide layer 1, and the nickel-plated layer 3 is disposed on the outside of the aluminum alloy layer 2 on both sides. The aluminum silicon carbide composite material is used to achieve high thermal conductivity, high strength, and a lower expansion coefficient relative to an external chip. The aluminum silicon carbide layer 1 can be improved by coating the aluminum alloy with aluminum alloy. The nickel-plated layer 3 is disposed on the outside of the aluminum alloy layer 2 on both sides, effectively improving the welding performance and salt spray resistance of the IGBT substrate and resolving the problem of poor welding performance of both aluminum silicon carbide and aluminum alloy. The nickel-plated layer 3 on one side is a planar structure and is used to form a welding surface 101, while the nickel-plated layer 3 on the other side is an arc-shaped structure and is used to form a heat dissipation surface 102. The heat dissipation surface 102 having an arc-shaped structure can achieve better heat dissipation. The grid-shaped solder resist tape 103 on the welding surface 101 can form multiple welding areas 104 by enclosing the grid of the solder resist tape 103. The solder resist tape 103 prevents the solder paste from flowing easily when the IGBT substrate is welded to the chip, thereby achieving the effect of solder resistance and ensuring smooth and high-quality welding of the chip.

[0039] Preferably, please refer to Figure 1 and 2 As shown, the side of the aluminum silicon carbide layer 1 close to the heat dissipation surface 102 is a curved surface structure, and the aluminum alloy layer 2 close to the heat dissipation surface 102 is an arc structure.

[0040] It can be understood that since the heat dissipation surface 102 is a curved surface structure, and the heat dissipation surface 102 is composed of a nickel-plated layer 3 with a curved structure, specifically, the side of the aluminum silicon carbide layer 1 close to the heat dissipation surface 102 is a first curved surface 11, the side of the aluminum alloy layer 2 close to the heat dissipation surface 102 is a second curved surface 21, and the outer side surface of the nickel-plated layer 3 with a curved structure is a third curved surface 31. The curvature of the first curved surface 11, the second curved surface 21 and the third curved surface 31 are similar. In order to ensure better adhesion between the aluminum alloy layer 2 and the nickel-plated layer 3 on the side close to the heat dissipation surface 102, and at the same time ensure better adhesion between the aluminum alloy layer 2 and the aluminum silicon carbide layer 1 on this side, so as to ensure the overall strength, reliability and heat dissipation performance of the aluminum silicon carbide substrate, the side of the aluminum silicon carbide layer 1 close to the heat dissipation surface 102 is designed as a curved surface structure, and the aluminum alloy layer 2 close to the heat dissipation surface 102 is designed as an arc structure, so that the integrity of the aluminum silicon carbide substrate is stronger, which is also beneficial to increase the connection strength between the aluminum silicon carbide layer 1, the aluminum alloy layer 2 and the nickel-plated layer 3, and avoid the occurrence of offset and dislocation between the layers.

[0041] According to another aspect of the present application, a method for preparing an IGBT substrate is provided, which is applied to the above-mentioned IGBT substrate. The method for preparing the IGBT substrate comprises the following steps:

[0042] S100: Selecting two silicon carbide particles of different particle sizes and mixing them evenly, adding an aqueous solution of aluminum dihydrogen phosphate at 1-2% of the total mass of the silicon carbide particles and water at 4% of the total mass of the silicon carbide particles, mixing evenly, drying and granulating to obtain an initial powder, pressing the initial powder into a green billet through a mold, and curing the green billet to obtain a silicon carbide preform billet;

[0043] S200: Processing the silicon carbide preform blank into a silicon carbide preform by CNC;

[0044] S300: placing the silicon carbide preform into a mold and preheating the mold together with the mold, pouring molten aluminum alloy after reaching the preheating temperature, and performing vacuum pressure infiltration to obtain an aluminum silicon carbide blank;

[0045] S400: CNC machining the aluminum silicon carbide blank to a preset size to obtain an aluminum silicon carbide substrate material;

[0046] S500: polishing and sandblasting the aluminum silicon carbide substrate material, and then performing surface nickel plating treatment to obtain the aluminum silicon carbide substrate;

[0047] S600 : The aluminum silicon carbide substrate is filled and etched by laser to form a grid-shaped solder resist 103 on the soldering surface 101 .

[0048] The preparation method of the IGBT substrate of the present application also has the above-mentioned beneficial effects. It also includes mixing silicon carbide particles of different particle sizes with an aqueous solution of aluminum dihydrogen phosphate and water to form an initial powder, using the initial powder to press and form a blank through a mold, and then solidifying the blank to obtain a silicon carbide preform blank. Based on the silicon carbide preform blank, a silicon carbide preform blank can be processed by CNC (numerical control machine tool) to obtain a silicon carbide preform. After the silicon carbide preform is preheated in the mold, molten aluminum alloy is poured and vacuum pressure infiltrated to obtain an aluminum silicon carbide blank. The aluminum silicon carbide blank is processed by CNC, polished, sandblasted, and then nickel-plated on the surface to obtain an aluminum silicon carbide base. Finally, a grid-shaped solder mask 103 is formed on the welding surface 101 by laser filling and etching, thereby completing the overall substrate preparation. The overall preparation process is very clear and efficient. By laser filling and etching the solder mask 103, compared with ink solder mask, the process is simple, the dimensional accuracy is high, and the production is efficient. It improves the solder resistance while solving the problem of the influence of the burrs on the edge of the line on the welding.

[0049] Preferably, step S100 specifically includes: mixing the first silicon carbide particles and the second silicon carbide particles evenly, wherein the particle size of the first silicon carbide particles is 80-100 μm, the particle size of the second silicon carbide particles is 8-12 μm, and the ratio of the first silicon carbide particles to the second silicon carbide particles is 8:2; then adding 1-2% of the total mass of the silicon carbide particles to the aluminum dihydrogen phosphate aqueous solution and 4% of the total mass of the silicon carbide particles to the water, mixing evenly, and then drying and granulating to obtain an initial powder, and the tap density of the initial powder is not less than 2.2 g / cm 3 The initial powder is pressed into a green billet by a mold under a pressure of 200 MPa, and the green billet is solidified at a temperature of 750° C. to obtain a silicon carbide preform blank.

[0050] It can be understood that two silicon carbide particles of different particle sizes, one of which has a much larger particle size than the other, and the proportion of the larger particle size silicon carbide particles in the total silicon carbide particles is 80%, can meet the requirement that the tap density of the initial powder is not less than 2.2 g / cm 3 At the same time, the initial powder is pressed into a blank through a mold at a pressure of 200 MPa, and the blank is solidified at a temperature of 750°C to obtain a silicon carbide preform blank, ensuring that the porosity of the silicon carbide preform blank obtained by processing the silicon carbide particle mixed raw material meets the requirements, and then ensuring that the thermal expansion coefficient of the aluminum silicon carbide material obtained after subsequent compounding with aluminum alloy meets the requirements, ensuring a better match between the IGBT substrate and the chip, and ensuring the high thermal reliability of the IGBT module.

[0051] It should be noted that two silicon carbide particles of different particle sizes are mixed evenly, and an aqueous solution of aluminum dihydrogen phosphate accounting for 1 to 2% of the total mass of the silicon carbide particles and water accounting for 4% of the total mass of the silicon carbide particles are added and mixed evenly, and then dried. The mixture is granulated by a granulator to obtain an initial powder, and the initial powder is pressed into a blank by a mold. The granulator and the mold are both existing devices and are not introduced in detail here.

[0052] Preferably, the porosity of the silicon carbide preform blank reaches 25%-31%, so that the thermal expansion coefficient of the aluminum silicon carbide substrate obtained by compounding the silicon carbide preform blank with the aluminum alloy reaches a preset value.

[0053] It is understandable that the porosity of the silicon carbide preform blank needs to reach 25%-31%, and the subsequent pouring of molten aluminum alloy must ensure good compounding with the aluminum alloy to ensure the smooth preparation of aluminum silicon carbide composite materials and achieve excellent properties such as high thermal conductivity, high strength, and a lower expansion coefficient than chips.

[0054] Preferably, the thermal expansion coefficient of the aluminum silicon carbide substrate is preset to 6-8 ppm / K, 50-150°C.

[0055] It can be understood that by setting the preset value of the thermal expansion coefficient of the aluminum silicon carbide substrate at 6-8ppm / K, 50-150℃, the expansion coefficient is lower than that of the chip welded to the IGBT substrate, which is conducive to better welding matching between the IGBT substrate and the chip, reducing the deformation of the IGBT substrate and other phenomena, and ultimately ensuring the high thermal reliability of the entire IGBT module composed of the IGBT substrate welded with the chip.

[0056] Preferably, when the silicon carbide preform is placed in the mold in step S300, a gap of 0.05-0.35 mm is left between the silicon carbide preform and the side wall of the mold, and then it is preheated to a preheating temperature of 580-650°C together with the mold, and the temperature of the poured molten aluminum alloy is 700-760°C.

[0057] It can be understood that by controlling the gap between the silicon carbide preform and the side wall of the mold to be 0.05-0.35 mm, a certain thickness of aluminum alloy can be reserved on the surface of the aluminum silicon carbide substrate, which facilitates the processing of the heat dissipation surface 102 with a curved surface structure on the surface of the aluminum silicon carbide substrate, solving the problem of difficulty in processing directly on the aluminum silicon carbide substrate.

[0058] Optionally, the heat dissipation surface 102 with a curved surface structure is machined on the surface of the aluminum silicon carbide substrate. Compared with the traditional curved surface net forming method, the accuracy of the curved surface curvature is guaranteed and the yield rate of the curvature forming is greatly improved.

[0059] Preferably, in step S400, one side of the aluminum silicon carbide blank is processed into a flat surface by CNC, and the opposite side is processed into a curved surface, and the curvature radius of the curved surface is in the range of 11000-17000.

[0060] It is understood that processing one side of the aluminum silicon carbide blank into a curved surface to serve as the heat dissipation surface 102, specifically, the heat dissipation surface 102 is a curved surface structure that convexly extends outward, which effectively increases the area of ​​the heat dissipation surface 102 and improves the heat dissipation effect of the heat dissipation surface 102. Due to the difference in expansion coefficient between the chip to be soldered and the aluminum silicon carbide substrate, the curvature of the aluminum silicon carbide substrate will become smaller after the chip is soldered. The curvature radius of the heat dissipation surface 102 is in the range of 11000-17000, which prevents the original curvature of the aluminum silicon carbide substrate from being too small, and avoids the curvature of the aluminum silicon carbide substrate from becoming negative after the chip is welded, that is, the heat dissipation surface 102 becomes concave, and the concave structure easily causes heat accumulation and difficulty in heat dissipation, which is not conducive to the heat dissipation of the IGBT module; at the same time, the curvature radius range of the heat dissipation surface 102 will not lead to the problem of the processing curvature radius being too small, and avoids the original curvature of the aluminum silicon carbide substrate from being too large, resulting in the curvature of the aluminum silicon carbide substrate being too large after the chip is welded, and the torque is too large when the IGBT module is installed, causing the risk of cracking the mounting hole of the aluminum silicon carbide substrate.

[0061] Preferably, in step S500 , a layer of nickel with a thickness of 5-20 μm is plated on the surface of the aluminum silicon carbide substrate material.

[0062] It is understandable that in order to improve the overall welding performance of the aluminum silicon carbide substrate and to improve the stability of the aluminum silicon carbide substrate welding chip, by plating a layer of 5-20μm thick nickel on the surface of the aluminum silicon carbide substrate material, the welding performance of the aluminum silicon carbide substrate can be effectively improved while controlling costs and reducing material waste. At the same time, the nickel coating can also effectively improve the salt spray performance of the aluminum silicon carbide substrate.

[0063] In this preferred embodiment, the thickness of the aluminum silicon carbide layer 1 in the center of the aluminum silicon carbide substrate is 2-5 mm, and the thickness of the aluminum alloy layer 2 is in the range of 0.05-0.35 mm. Under the premise of effectively controlling costs and avoiding material waste, various performance parameters of the aluminum silicon carbide substrate can be guaranteed.

[0064] Preferably, in step S600, the power of the laser is 30-100 W, the frequency is 50 Hz, and the scanning speed is 600 mm / s; the laser etching depth is 1-4 μm, and the etching width is 1-20 mm.

[0065] It is understandable that by controlling the laser etching depth within the range of 1-4 μm, it is possible to avoid etching too shallowly, which would be detrimental to the formation of the solder resist tape 103 or reduce the solder resistance performance of the solder resist tape 103, and to prevent etching too deeply, which would cause burning through the nickel plating layer 3. Increasing the laser etching width to greater than 1 mm effectively improves the solder resistance of the substrate, reduces the difficulty of etching, and avoids the phenomenon of burning through the nickel layer due to excessive etching. At the same time, controlling the laser etching width to less than 20 mm reduces the impact of burrs caused by etching on welding performance and on the salt spray performance of the aluminum silicon carbide substrate, thereby achieving an overall effect of improving the processing quality of the aluminum silicon carbide substrate.

[0066] In summary, the present application processes the solder mask 103 on the nickel-plated layer 3 of the aluminum silicon carbide substrate through laser filling and etching, that is, an oxidized area of ​​a certain width is formed on the nickel-plated layer 3, which prevents the solder paste from flowing when the aluminum silicon carbide substrate is soldered to the chip, thereby achieving the effect of solder mask. Compared with ink solder mask, the process is simple, the dimensional accuracy is high, and the production is efficient; and the etching depth is small and the width is large, which improves the solder mask ability while solving the problem of the influence of burrs on the edge of the engraved line on welding. At the same time, due to the small etching depth, the nickel layer on the surface of the substrate is avoided from being burned through, thereby ensuring the salt spray performance of the substrate.

[0067] It should be noted that, in this article, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements that are inherent to such process, method, article or apparatus.

[0068] This article uses specific examples to illustrate the principles and implementation methods of this application. The above examples are only used to help understand the method and core ideas of this application. The above is only the preferred implementation method of this application. It should be pointed out that due to the limitations of textual expression, there are objectively infinite specific structures. For ordinary technicians in this technical field, without departing from the principles of this application, they can make several improvements, modifications or changes, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the inventive concept and technical solution to other occasions without improvement, should be regarded as protected by this application.

Claims

1. An IGBT substrate, characterized in that: The invention comprises a substrate body (100), wherein the substrate body (100) comprises an aluminum silicon carbide layer (1), an aluminum alloy layer (2) is provided on opposite sides of the aluminum silicon carbide layer (1), a nickel plating layer (3) is provided on the outer side of the aluminum alloy layer (2), the nickel plating layer (3) on one side of the substrate body (100) is a planar structure and is used to form a welding surface (101), the nickel plating layer (3) on the other side of the substrate body (100) is an arc structure and is used to form a heat dissipation surface (102), a grid-shaped solder resist tape (103) is provided on the welding surface (101), the grid of the solder resist tape (103) encloses a welding area (104), and the solder resist tape (103) is used to prevent solder paste from flowing when an IGBT substrate is welded to a chip through the welding area (104).

2. The IGBT substrate according to claim 1, characterized in that: The side of the aluminum silicon carbide layer (1) close to the heat dissipation surface (102) is a curved surface structure, and the aluminum alloy layer (2) close to the heat dissipation surface (102) is an arc-shaped structure.

3. A method for preparing an IGBT substrate, characterized in that: Applied to the IGBT substrate according to any one of claims 1 to 2, the IGBT substrate preparation method comprises the following steps: S100: Selecting two silicon carbide particles of different particle sizes and mixing them evenly, adding an aqueous solution of aluminum dihydrogen phosphate at 1-2% of the total mass of the silicon carbide particles and water at 4% of the total mass of the silicon carbide particles, mixing evenly, drying and granulating to obtain an initial powder, pressing the initial powder into a green billet through a mold, and curing the green billet to obtain a silicon carbide preform billet; S200: Processing the silicon carbide preform blank into a silicon carbide preform by CNC; S300: placing the silicon carbide preform into a mold and preheating the mold together with the mold, pouring molten aluminum alloy after reaching the preheating temperature, and performing vacuum pressure infiltration to obtain an aluminum silicon carbide blank; S400: CNC machining the aluminum silicon carbide blank to a preset size to obtain an aluminum silicon carbide substrate material; S500: polishing and sandblasting the aluminum silicon carbide substrate material, and then performing surface nickel plating treatment to obtain the aluminum silicon carbide substrate; S600: The aluminum silicon carbide substrate is filled and etched by laser to form a grid-shaped solder resist strip (103) on the welding surface (101).

4. The method for preparing an IGBT substrate according to claim 3, wherein: Step S100 specifically includes: mixing the first silicon carbide particles and the second silicon carbide particles evenly, wherein the particle size of the first silicon carbide particles is 80-100 μm, the particle size of the second silicon carbide particles is 8-12 μm, and the ratio of the first silicon carbide particles to the second silicon carbide particles is 8:2; then adding 1-2% of the total mass of the silicon carbide particles to an aqueous solution of aluminum dihydrogen phosphate and 4% of the total mass of the silicon carbide particles to water, mixing evenly, and then drying and granulating to obtain an initial powder, the tap density of the initial powder is not less than 2.2 g / cm3, the initial powder is pressed into a blank by a mold at a pressure of 200 MPa, and the blank is cured at a temperature of 750°C to obtain a silicon carbide preform blank.

5. The method for preparing an IGBT substrate according to any one of claims 3 or 4, characterized in that: The porosity of the silicon carbide preform blank reaches 25%-31%, so that the thermal expansion coefficient of the aluminum silicon carbide substrate obtained by compounding the silicon carbide preform blank with the aluminum alloy reaches a preset value.

6. The method for preparing an IGBT substrate according to claim 5, wherein: The thermal expansion coefficient of the aluminum silicon carbide substrate is preset to 6-8ppm / K, 50-150℃.

7. The method for preparing an IGBT substrate according to claim 3, wherein: When the silicon carbide preform is placed in the mold in step S300, a gap of 0.05-0.35 mm is left between the silicon carbide preform and the side wall of the mold. The preform is then preheated to a preheating temperature of 580-650°C together with the mold, and the temperature of the poured molten aluminum alloy is 700-760°C.

8. The method for preparing an IGBT substrate according to claim 3, wherein: In step S400, one side of the aluminum silicon carbide blank is processed into a flat surface by CNC, and the opposite side is processed into a curved surface, and the curvature radius of the curved surface ranges from 11000 to 17000.

9. The method for preparing an IGBT substrate according to claim 3, wherein: In step S500 , a layer of nickel with a thickness of 5-20 μm is plated on the surface of the aluminum silicon carbide substrate material.

10. The method for preparing an IGBT substrate according to claim 3, wherein: In step S600 , the power of the laser is 30-100 W, the frequency is 50 Hz, and the scanning speed is 600 mm / s; the laser etching depth is 1-4 μm, and the etching width is 1-20 mm.

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