Sintering method and power device

Abstract

The invention provides a sintering method and a power device, and the method comprises the steps: coating a sintering surface of a ceramic substrate / heat dissipation substrate of the power device with a connecting material, so as to form a connecting material layer which comprises a plurality of independent partitions, the position of each independent partition corresponds to the position of at least one chip of the power device; the ceramic substrate / the heat dissipation substrate coated with the connecting material layer and the heat dissipation substrate / the ceramic substrate are subjected to surface mounting, so that a to-be-sintered part is formed; and carrying out pressure sintering on the to-be-sintered part so as to complete the connection between the ceramic substrate and the heat dissipation substrate. Through the application, not only can the use amount of the connecting material be saved and the large-area sintering cost be reduced, but also the intervals between the independent subareas can be used as volatilization channels of a solvent in the drying and sintering process, so that the formation of holes and air channels in the connecting material layer during drying and sintering is reduced or avoided, and the heat dissipation performance of the connecting layer after sintering is improved.

Description

Technical Field

[0001] The present application relates to the technical field of power device preparation, and in particular to a sintering method and a power device. Background Art

[0002] The current power module integration is getting higher and higher, and the number of chips used inside is increasing, which leads to the increasing area of ​​the copper-clad ceramic substrate of the power module, that is, the area of ​​the connection between the power module and the heat sink becomes larger. For the connection between the silicon carbide power module and the heat sink, the sintering solution can improve the thermal conductivity and connection strength of the connection layer, and more effectively exert the performance of the silicon carbide chip.

[0003] Since sintering usually uses sintering silver paste and sintering copper paste as connection materials, their current prices are basically close to or even higher than the price of precious metals, and the cost is relatively high. For power modules, the effective heat dissipation path is mainly concentrated directly under the chip, and the area far away from the chip contributes less to heat dissipation. Therefore, for such large-area sintering, if the coating solution covering the entire sintering surface is still used, it will lead to a great consumption of connection materials.

[0004] On the other hand, if the coating area covers the entire copper surface of the copper-clad ceramic substrate, the large area of ​​sintered silver paste and sintered copper paste is not conducive to the volatilization of the solvent during the sintering process, which is likely to cause more holes, airways, etc. and affect the heat dissipation performance of the connection layer.

[0005] Therefore, it is necessary to find a solution that can reduce the cost of large-area sintering without affecting the sintering performance. Summary of the invention

[0006] In view of the above-mentioned problems in the prior art, the purpose of the present application is to provide a sintering method and a power device, which can reduce the large-area sintering cost without affecting the sintering performance.

[0007] To achieve the above-mentioned purpose and other related purposes, the present application provides a sintering method, which is applied to the interconnection between a ceramic substrate and a heat dissipation substrate of a power device, wherein the power device includes a plurality of chips, and the sintering method includes:

[0008] Applying a connection material on the sintering surface of the ceramic substrate / the heat dissipation substrate to form a connection material layer, wherein the connection material layer includes a plurality of independent partitions, and the position of each of the independent partitions corresponds to the position of at least one chip of the power device;

[0009] Mounting the ceramic substrate / the heat dissipation substrate coated with the connection material and the heat dissipation substrate / the ceramic substrate to form a to-be-sintered part;

[0010] The sintered part is subjected to pressure sintering to complete the connection between the ceramic substrate and the heat dissipation substrate.

[0011] In an optional embodiment of the present application, a vertical projection of a chip corresponding to each independent partition on the connection material layer is located within each independent partition.

[0012] In an optional embodiment of the present application, a connection material is coated on the sintering surface of the ceramic substrate / the heat dissipation substrate to form a connection material layer, including:

[0013] forming a coating on the sintered surface of the ceramic substrate / the heat dissipation substrate;

[0014] A connection material is coated on the sintered surface of the ceramic substrate / the heat dissipation substrate on which the plating layer is formed to form a connection material layer, wherein the plating layer is a silver plating layer, a nickel plating layer, a copper plating layer or a titanium plating layer.

[0015] In an optional embodiment of the present application, a connection material is coated on the sintering surface of the ceramic substrate / the heat dissipation substrate to form a connection material layer, including:

[0016] The connection material is coated on the sintering surface of the ceramic substrate / the heat dissipation substrate by using a steel screen printing method or a dispensing coating method to form a connection material layer.

[0017] In an optional embodiment of the present application, in the step of coating the connection material on the sintering surface of the ceramic substrate / the heat dissipation substrate to form a connection material layer, the coating thickness is between 10 μm and 800 μm.

[0018] In an optional embodiment of the present application, in the step of coating a connecting material on the sintering surface of the ceramic substrate / the heat dissipation substrate to form a connecting material layer, the connecting material is a sintering silver paste or a sintering copper paste.

[0019] In an optional embodiment of the present application, the spacing between each independent partition is between 1 mm and 10 mm.

[0020] In an optional embodiment of the present application, the ceramic substrate is a copper-clad ceramic substrate packaged in the power module and exposing a sintered surface, or a copper-clad ceramic substrate not packaged in the power module.

[0021] In an optional embodiment of the present application, the boundary of each of the independent partitions avoids the etching groove on the internal metal layer of the ceramic substrate.

[0022] To achieve the above-mentioned purpose and other related purposes, the present application also provides another sintering method, which is applied to the interconnection between the ceramic substrate and the heat dissipation substrate of a power device, wherein the power device includes a plurality of chips, and the sintering method includes:

[0023] Coating a connection material on the sintered surfaces of the ceramic substrate and the heat dissipation substrate respectively to form a connection material layer, wherein the connection material layer includes a plurality of independent partitions, and the position of each independent partition corresponds to the position of at least one chip of the power device, and the connection material of at least one independent partition is coated on the connection surface of the ceramic substrate, and the connection materials of other independent partitions are coated on the connection surface of the heat dissipation substrate;

[0024] Mounting the ceramic substrate coated with the connection material and the heat dissipation substrate to form a to-be-sintered component;

[0025] The sintered part is subjected to pressure sintering to complete the connection between the ceramic substrate and the heat dissipation substrate.

[0026] In order to achieve the above-mentioned purpose and other related purposes, the present application also provides a power device, wherein the ceramic substrate and the heat dissipation substrate of the power device are interconnected by adopting the above-mentioned method.

[0027] The sintering method of the present application is applied to a large-area sintering process. When the connecting material is coated between the connecting area between the ceramic substrate and the heat dissipation substrate of the power device, the entire connecting area is first divided into several independent areas for coating to ensure that the area corresponding to each chip of the power device has a connecting material layer to ensure effective heat transfer, and the connecting material is partially coated on the peripheral area below the chip, thereby forming a connecting material layer including multiple independent partitions on the sintering surface of the ceramic substrate and / or the heat dissipation substrate. This not only saves the amount of connecting material and reduces the cost of large-area sintering, but also the intervals between the independent partitions can also serve as solvent volatilization channels during drying and sintering, thereby reducing or avoiding the formation of holes and airways in the connecting material layer during drying and sintering, and improving the heat dissipation performance of the connecting layer between the ceramic substrate and the heat dissipation substrate after sintering.

[0028] In the sintering method of the present application, when a connecting material layer including multiple independent partitions is coated on the sintering surface of the ceramic substrate and / or the heat dissipation substrate, the boundaries of each independent partition avoid the etched grooves on the internal metal layer of the ceramic substrate, thereby preventing the ceramic substrate from experiencing stress concentration in the overlapping area due to the overlap between the connecting material layer and the etched grooves on the internal metal layer of the ceramic substrate, thereby preventing the ceramic in the ceramic substrate from cracking and causing insulation failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a flow chart of a sintering method in one embodiment of the present application.

[0030] Figure 2 This is a schematic diagram of a coating pattern for coating a connection material on a sintering surface of a ceramic substrate in the present application.

[0031] Figure 3This is a schematic diagram of another coating pattern for coating the connection material on the sintering surface of the ceramic substrate in the present application.

[0032] Figure 4 This is a schematic diagram of another coating pattern for coating a connection material on a sintering surface of a ceramic substrate in the present application.

[0033] Figure 5 A photograph of a copper-clad ceramic substrate coated with two independent partition connection material layers.

[0034] Figure 6 Ultrasonic scanning microscope image of the power device after sintering. DETAILED DESCRIPTION

[0035] The following describes the embodiments of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0036] It should be noted that the diagrams provided in the following embodiments are only schematic illustrations of the basic concept of the present application, and the diagrams only show the components related to the present application rather than the number, shape and size of the components in actual implementation. The type, quantity and proportion of each component in actual implementation can be changed at will, and the layout of the components may be more complicated. The area of ​​each independent partition is larger than the area of ​​the corresponding chip, and each independent partition is located below the corresponding chip and in its peripheral area.

[0037] like Figure 1 As shown, the present application proposes a sintering method. The sintering method is applied to the large-area interconnection sintering process between the ceramic substrate and the heat dissipation substrate of the power device. When the connection material is applied between the connection area between the ceramic substrate and the heat dissipation substrate of the power device, the entire connection area is first divided into several independent areas for coating, ensuring that the area corresponding to each chip of the power device has a connection material layer to ensure effective heat transfer, and the connection material is partially applied to the peripheral area below the chip, thereby forming a connection material layer including multiple independent partitions on the sintering surface of the ceramic substrate and / or the heat dissipation substrate. This not only saves the amount of connection material and reduces the cost of large-area sintering, but also the intervals between the independent partitions can also be used as a solvent volatilization channel during the drying and sintering process, thereby reducing or avoiding the formation of holes and airways in the connection material layer during drying and sintering, and improving the heat dissipation performance of the connection layer after sintering.

[0038] The power device includes a power module, a heat dissipation substrate, and a connection layer to interconnect the two. The power module is an injection-molded power module with multiple chips, which has parts and connections to achieve certain functions, including but not limited to silicon-based chips, silicon carbide-based chips, diodes, bonding wires, copper bridges, lead frames, ceramic substrates, sensors, plastic packaging materials, gaskets and other parts and their combinations.

[0039] The ceramic substrate can be an AMB (Active Metal Brazing) substrate or a DBC (Direct Bonding Copper) substrate. Taking the copper-clad ceramic substrate as an example, it is a ceramic substrate with copper metal layers formed on both sides, wherein the copper metal layer inside the power module is used to connect with the chip, and a circuit is etched thereon, and the copper metal layer outside the power module is used to interconnect with the heat dissipation substrate for heat dissipation.

[0040] The heat dissipation substrate is a substrate with heat dissipation function that can be in direct contact with the coolant. Its material can be copper or aluminum, that is, the heat dissipation substrate can be a copper heat dissipation substrate or an aluminum heat dissipation substrate. The heat dissipation substrate can be a liquid cooling radiator, for example, to achieve heat dissipation of the power module. The liquid cooling radiator can be a liquid cooling radiator with flaps, or a liquid cooling radiator with spoilers.

[0041] Figure 1 The process flow chart of the sintering method of the present application is shown, including:

[0042] Step S110, coating a connection material on the sintering surface of the ceramic substrate / the heat dissipation substrate to form a connection material layer, wherein the connection material layer includes a plurality of independent partitions, and the position of each of the independent partitions corresponds to the position of at least one chip of the power device;

[0043] Step S120, mounting the ceramic substrate / the heat dissipation substrate coated with the connection material and the heat dissipation substrate / the ceramic substrate to form a part to be sintered;

[0044] Step S130 , pressurizing and sintering the part to be sintered to complete the connection between the ceramic substrate and the heat dissipation substrate.

[0045] In step S110, when applying the connection material, it can be applied on the sintered surface of the ceramic substrate or on the sintered surface of the heat dissipation substrate, or the connection material can be applied on the sintered surface of the ceramic substrate and the sintered surface of the heat dissipation substrate respectively and then combined to form a final connection material layer.

[0046] For the sake of convenience, the following will be combined with the attached Figure 2-4 As shown, the entire coating process is described in detail by coating the connection material on the sintering surface 101 of the ceramic substrate 10.

[0047] The connection material can be applied on the sintering surface 101 of the ceramic substrate 10 by steel screen printing or dispensing to form a connection material layer 20, wherein the connection material layer 20 includes a plurality of independent partitions, and the position of each independent partition corresponds to the position of at least one chip of the power device.

[0048] The ceramic substrate 10 can be a copper-clad ceramic substrate that is packaged in the power module and only exposes the metal surface, or it can be a copper-clad ceramic substrate that is not packaged in the power module. The ceramic substrate 10 has a sintered surface 101. The sintered surface 101 refers to the metal surface of the copper-clad ceramic substrate 10 that is in direct contact with the connecting material. It can be a bare copper surface, a silver-plated surface, a nickel-plated surface, or a titanium-plated surface, or a combination of copper, silver, nickel, aluminum, titanium, etc. The coating can improve the oxidation resistance, corrosion resistance and sintering processability of the substrate. The coating can be implemented by chemical plating, electroplating, physical vapor deposition, etc., which is not limited here.

[0049] Taking the silver-plated layer as an example, due to the chemical stability and high oxidation temperature of silver, a silver-plated layer is formed on the sintering surface 101 of the ceramic substrate 10 and / or on the sintering surface 101 of the heat dissipation substrate. In the subsequent sintering process, the silver-plated layer can promote the diffusion connection between the sintered material and the interface, further enhancing the interface connection strength; on the other hand, the silver-plated layer can also hinder the oxidation of the copper matrix during the subsequent sintering process and the high-temperature service process of the power device, further ensuring the connection strength of the interface and preventing the interface oxidation of the product during the sintering process and the high-temperature service process. And by silver-plating the ceramic substrate 10 and / or the heat dissipation substrate, after sintering, the reliability between the heat dissipation substrate and the ceramic substrate 10 can be further improved.

[0050] As an example, the thickness of the coating is between 0.05 μm and 2 μm, such as 0.05 μm, 0.1 μm, 0.3 μm, 0.5 μm, 0.7 μm, 0.9 μm, 1 μm, 1.5 μm, 2 μm, etc. For large-area sintering, the metal surface area of ​​the ceramic substrate 10, i.e., the area of ​​the sintering surface 101, is not less than 500 mm 2 .

[0051] Before coating the connecting material layer 20 on the sintered surface 101 of the ceramic substrate 10, if there are pollutants and / or oxides on the sintered surface 101, it is necessary to first perform a pretreatment process such as cleaning and drying on the sintered surface 101 of the ceramic substrate 10 to remove the pollutants and / or oxides on its surface, thereby improving the adhesion between the connecting material and the sintered surface 101, increasing the connection strength between the connecting material and the sintered surface 101, and increasing the reliability of the power device.

[0052] After pre-treating the sintering surface 101 of the ceramic substrate 10, a connection material layer 20 can be coated on the sintering surface 101 of the ceramic substrate 10 by stencil printing or dispensing to form a connection material layer 20 (as a connection layer). The connection material can be, for example, sintering silver paste, sintering copper paste, etc., and the sintering silver paste or sintering copper paste is a mixture of metal particles and an organic solvent.

[0053] When the connection material layer 20 is coated on the sintering surface 101 of the ceramic substrate 10, the number and shape of the independent partitions in the connection material layer 20 can be reasonably designed according to the position of the chip in the power module to form a similar Figure 2-4 The coating pattern shown is to divide the entire connecting material layer 20 originally corresponding to each power module into multiple independent partitions according to the position of the chip in the power module, so that the position of each independent partition corresponds to the position of at least one chip of the power device, so that the ceramic substrate 10 of each power device and the heat dissipation substrate can be sintered and interconnected through the connecting material layer 20 with multiple independent partitions. This not only saves the amount of connecting material and reduces the cost of large-area sintering, but also the intervals between the independent partitions of the connecting material layer 20 can also serve as volatilization channels for the solvent during the drying and sintering process, thereby reducing or avoiding the formation of holes and airways in the connecting material layer 20 during subsequent drying and sintering, and improving the heat dissipation performance of the connecting layer after sintering.

[0054] When applying, the number of times of application can be single or multiple. When applying multiple times, the coating direction can be in the same direction each time, or in different directions each time.

[0055] During coating, the outer contour of the connection material layer 20 is smaller than the outer contour of the sintering surface 101 of the ceramic substrate 10 , that is, the connection material is completely inside the metal surface of the ceramic substrate 10 without overflowing.

[0056] When coating, the coating thickness, that is, the thickness of the connection material layer 20, should be reasonably selected according to actual needs. It should not be too thick or too thin. If the thickness is too thin, it is easy to break and delaminate, and it is difficult to form an effective connection; if the thickness is too thick, it is difficult to control the thickness of the final connection layer, the amount of solvent volatilization, and the thermal resistance is increased. As an example, the coating thickness is between 10μm-800μm, such as 10μm, 30μm, 60μm, 90μm, 120μm, 200μm, 300μm, 400μm, 500μm, 600μm, 700μm, 800μm.

[0057] When forming a connection material layer 20 including a plurality of independent partitions on the sintering surface 101 of the ceramic substrate 10, it is necessary to take into account the circuit design inside the copper-clad ceramic substrate 10, that is, the etched grooves on the internal metal layer of the copper-clad ceramic substrate 10. The boundaries of each independent partition avoid the etched grooves on the internal metal layer of the ceramic substrate 10 as much as possible, so as to prevent the stress concentration phenomenon in the overlapped area of ​​the ceramic substrate 10 caused by the overlap of the connection material layer 20 and the etched grooves on the internal metal layer of the ceramic substrate 10, thereby causing the ceramic in the ceramic substrate 10 to crack and cause insulation failure. Of course, the boundaries of each independent partition may also overlap with the etched grooves on the internal metal layer of the ceramic substrate 10. The overlap length is not limited here and can be defined in combination with theoretical simulation calculations or experiments, as long as the functional requirements of the product are met.

[0058] It should be noted that the method of coating the connection material on the sintered surface of the heat dissipation substrate is the same as the method of coating the connection material on the sintered surface 101 of the ceramic substrate 10 , so it will not be described in detail here.

[0059] In step S120 and step S130, the connecting material layer 20 can be dried first, and then the ceramic substrate 10 coated with the connecting material is mounted on the heat dissipation substrate to form a sintered part; the sintered part is placed in a sintering device for sintering, so that the solvent in the connecting material is further volatilized and the metal particles undergo atomic diffusion, and finally the connecting material is mechanically connected to the heat dissipation substrate and the ceramic substrate 10 at the same time, thereby forming a reliable system connection layer between the heat dissipation substrate and the ceramic substrate 10.

[0060] The sintering parameters are as follows: sintering temperature is between 180-260, for example, 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃; sintering time is between 5min-20min, for example, 5min, 10min, 15min, 20min; sintering pressure is between 6MPa-25MPa, for example, 6MPa, 8MPa, 10MPa, 12MPa, 15MPa, 20MPa, 25MPa.

[0061] It should be noted that the sintering temperature is crucial during the sintering process. Too high a temperature will damage the parts (chips, bonding wires, plastic packaging materials, etc.) in the power module, while too low a sintering temperature will cause the connection materials to fail to form an effective connection.

[0062] It should be noted that, when the sintered part is pressurized and sintered to complete the connection between the ceramic substrate 10 and the heat dissipation substrate, a fixed target sintering pressure can be used, or the target sintering pressure can be reached by gradually increasing the pressure. When the sintering is completed, the sintering pressure can be released by gradually reducing the pressure. The pressurization rate is 0.05MPa / s-1.5MPa / s, for example, 0.05MPa / s, 0.1MPa / s, 0.3MPa / s, 0.5MPa / s, 0.8MPa / s, 1.0MPa / s, 1.2MPa / s, 1.5MPa / s, and the pressure reduction rate is 0.05MPa / s-1.5MPa / s, for example, 0.05MPa / s, 0.1MPa / s, 0.3MPa / s, 0.5MPa / s, 0.8MPa / s, 1.0MPa / s, 1.2MPa / s, 1.5MPa / s.

[0063] The use of pressure sintering can not only enhance the density of the sintered connecting material layer 20 and the connection strength between the heat dissipation substrate and the ceramic substrate 10, but also prevent the heat dissipation substrate and the ceramic substrate 10 from warping during the sintering process, thereby making the sintering method of the present application suitable for large-area reliable interconnection between the ceramic substrate 10 and the heat dissipation substrate.

[0064] During the sintering process, the sintering atmosphere needs to be selected according to the material of the sintering surface 101 and the connecting material. For example, if the sintering surface 101 is a silver-plated surface, a nickel-plated surface or a titanium-plated surface, and the connecting material is a sintered silver paste, the sintering atmosphere can be vacuum, nitrogen or air. For example, if the sintering surface 101 is a bare copper surface or a sintered copper paste, the sintering atmosphere can be vacuum or nitrogen to prevent oxidation of the bare copper surface or the copper paste.

[0065] During the cooling process to room temperature after sintering, the choice of cooling atmosphere also needs to be selected according to the material of the sintering surface 101 and the connecting material. For example, if the sintering surface 101 is a silver-plated surface, a nickel-plated surface or a titanium-plated surface, and the connecting material is a sintered silver paste, the cooling atmosphere can be nitrogen or air. For example, if the sintering surface 101 is a bare copper surface or a sintered copper paste, the sintering atmosphere can be nitrogen to prevent oxidation of the bare copper surface or the copper paste.

[0066] It should be noted that, in an optional embodiment, in order to improve the sintering efficiency and sintering quality, before sintering, the to-be-sintered part may be preheated in a sintering atmosphere; then the preheated part may be pressurized and sintered to complete the connection between the ceramic substrate 10 and the heat dissipation substrate.

[0067] It should be noted that, in addition to coating a sintered material layer on the heat dissipation substrate or the ceramic substrate 10, sintered materials can also be coated on the heat dissipation substrate or the ceramic substrate 10 respectively and then combined. Specifically, a connecting material can be coated on the sintering surfaces 101 of the ceramic substrate 10 and the heat dissipation substrate respectively to form a connecting material layer 20, the connecting material layer 20 includes a plurality of independent partitions, the position of each of the independent partitions corresponds to the position of at least one chip of the power device, the connecting material of at least one independent partition is coated on the connecting surface of the ceramic substrate 10, and the connecting materials of other independent partitions are coated on the connecting surface of the heat dissipation substrate; the ceramic substrate 10 coated with the connecting material and the heat dissipation substrate are mounted to form a part to be sintered; the part to be sintered is pressure-sintered to complete the connection between the ceramic substrate 10 and the heat dissipation substrate. Figure 2 Taking the two rectangular independent partitions shown as an example, the connection material of one rectangular independent partition is coated on the connection surface of the ceramic substrate 10, and the connection material of the other independent partition is coated on the connection surface of the heat dissipation substrate.

[0068] Several specific examples of the coating scheme of the present application are given below.

[0069] Example 1: Using similar Figure 2 The coating pattern shown, on the injection molded power module, the exposed metal surface area of ​​the copper-clad ceramic substrate AMB is 40mm*50mm, the surface is silver-plated, and the thickness of the silver plating layer is 0.8μm. The sintered silver paste is coated in the manner of steel screen printing, and the printing is done twice, in opposite directions; the steel screen thickness is 600μm. The printed shape is two rectangles, with dimensions of 39mm*14mm, 10mm apart, and symmetrically centered relative to the copper-clad ceramic substrate AMB.

[0070] Example 2: Using similar Figure 3 The coating pattern shown is to apply sintered copper paste on the heat dissipation substrate by dot coating, with a coating thickness of 300μm, and a coating shape of 4 rectangles with dimensions of 20mm*18mm, 5mm spacing in the length direction, and 2mm spacing in the width direction, symmetrically centered relative to the heat dissipation substrate. The heat dissipation substrate is made of copper, with a silver-plated surface and a silver-plated layer thickness of 3μm.

[0071] Example 3: Using similar Figure 4 The coating pattern shown is directly coated on the copper-clad ceramic substrate AMB. The exposed metal surface area on the AMB is 40mm*50mm. The surface is silver-plated with a thickness of 0.5μm. The sintered silver is coated by printing using a steel mesh. The printing is done once and the thickness of the steel mesh is 100um. The printed shape is a plurality of irregular patterns.

[0072] Taking Example 1 as an example, Figure 5 The photo shows two rectangular independent partitions coated on a silver-plated copper-clad ceramic substrate. After coating, the surface of the sintered silver paste is flat and there are no missing or missing prints. Ultrasonic scanning after sintering shows that the sintered silver paste has no defects such as stratification, cracking, and air channels. Compared with the method of coating the entire area according to the size of 39mm*49mm, the amount of connecting material used is reduced by 43%, which greatly reduces the cost.

[0073] To summarize, the sintering method of the present application is applied to a large-area sintering process. When the connecting material is coated between the connecting area between the ceramic substrate of the power device and the heat dissipation substrate, the entire connecting area is first divided into several independent areas for coating to ensure that the areas corresponding to each chip of the power device have a connecting material layer to ensure effective heat transfer, and the connecting material is partially coated on the peripheral area below the chip, thereby forming a connecting material layer including multiple independent partitions on the sintering surface of the ceramic substrate and / or the heat dissipation substrate. This not only saves the amount of connecting material and reduces the cost of large-area sintering, but also the intervals between the independent partitions can also serve as a solvent volatilization channel during the drying and sintering process, thereby reducing or avoiding the formation of holes and airways in the connecting material layer during drying and sintering, and improving the heat dissipation performance of the connecting layer between the ceramic substrate and the heat dissipation substrate after sintering.

[0074] In the sintering method of the present application, when a connecting material layer including multiple independent partitions is coated on the sintering surface of the ceramic substrate and / or the heat dissipation substrate, the boundaries of each independent partition avoid the etched grooves on the internal metal layer of the ceramic substrate, thereby preventing the ceramic substrate from experiencing stress concentration in the overlapping area due to the overlap between the connecting material layer and the etched grooves on the internal metal layer of the ceramic substrate, thereby preventing the ceramic in the ceramic substrate from cracking and causing insulation failure.

[0075] In the description herein, many specific details are provided, such as examples of parts and / or methods, to provide a complete understanding of the embodiments of the present application. However, those skilled in the art will recognize that the embodiments of the present application can be practiced without one or more specific details or by other devices, systems, components, methods, parts, materials, parts, etc. In other cases, known structures, materials or operations are not specifically shown or described in detail to avoid blurring the aspects of the embodiments of the present application.

[0076] References throughout the specification to "one embodiment," "an embodiment," or "a specific embodiment" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment is included in at least one embodiment of the present application, and not necessarily in all embodiments. Thus, various appearances of the phrases "in one embodiment," "in an embodiment," or "in a specific embodiment" in different places throughout the specification do not necessarily refer to the same embodiment. In addition, the particular features, structures, or characteristics of any specific embodiment of the present application may be combined with one or more other embodiments in any suitable manner. It should be understood that other variations and modifications of the embodiments of the invention described and illustrated herein may be possible in accordance with the teachings herein and are to be considered part of the spirit and scope of the present application.

[0077] It should also be understood that one or more of the elements shown in the figures may also be implemented in a more separate or more integrated manner, or even removed because they are inoperable in certain circumstances or provided because they may be useful depending on the application.

[0078] In addition, unless otherwise explicitly indicated, any marking arrows in the drawings should be regarded as exemplary only and not limiting. In addition, unless otherwise indicated, the term "or" used herein is generally intended to mean "and / or". In the case where the term is not clear because it is anticipated that the ability to separate or combine is provided, the combination of components or steps will also be regarded as indicated.

[0079] As used in the description herein and throughout the claims that follow, "a", "an", and "the" include plural references unless otherwise indicated. Likewise, as used in the description herein and throughout the claims that follow, the meaning of "in" includes "in" and "on" unless otherwise indicated.

[0080] The above description of the embodiment shown in the application (including the content described in the abstract of the specification) is not intended to be exhaustive or to limit the application to the precise form disclosed herein. Although the specific embodiment of the application and the example of the application are described herein for the purpose of illustration only, as those skilled in the art will recognize and understand, various equivalent modifications can be within the spirit and scope of the application. As pointed out, these modifications can be made to the application according to the above description of the embodiment described in the application, and these modifications will be within the spirit and scope of the application.

[0081] This paper has generally described systems and methods as details that are helpful for understanding the application. In addition, various specific details have been given to provide an overall understanding of the embodiments of the application. However, those skilled in the relevant art will recognize that the embodiments of the application can be put into practice without one or more specific details, or put into practice using other devices, systems, accessories, methods, assemblies, materials, parts, etc. In other cases, known structures, materials and / or operations are not particularly shown or described in detail to avoid confusion in various aspects of the embodiments of the application.

[0082] Thus, although the present application has been described herein with reference to specific embodiments thereof, freedom of modification, various changes and substitutions are also within the above disclosure, and it should be understood that in some cases, some features of the present application will be adopted without corresponding use of other features without departing from the scope and spirit of the proposed invention. Therefore, many modifications may be made to adapt specific environments or materials to the substantial scope and spirit of the present application. The present application is not intended to be limited to the specific terms used in the claims below and / or the specific embodiments disclosed as the best mode for carrying out the present application, but the present application will include any and all embodiments and equivalents falling within the scope of the appended claims. Thus, the scope of the present application will be determined solely by the appended claims.

Claims

1. A sintering method, applied to the interconnection between a ceramic substrate and a heat dissipation substrate of a power device, wherein the power device comprises a plurality of chips, characterized in that: The sintering method comprises: Applying a connection material on the sintering surface of the ceramic substrate / the heat dissipation substrate to form a connection material layer, wherein the connection material layer includes a plurality of independent partitions, and the position of each of the independent partitions corresponds to the position of at least one chip of the power device; Mounting the ceramic substrate / the heat dissipation substrate coated with the connection material and the heat dissipation substrate / the ceramic substrate to form a to-be-sintered part; The sintered part is subjected to pressure sintering to complete the connection between the ceramic substrate and the heat dissipation substrate.

2. The sintering method according to claim 1, characterized in that: The vertical projections of the chips corresponding to the independent partitions on the connection material layer are located within the independent partitions.

3. The sintering method according to claim 1, characterized in that: Applying a connection material on the sintering surface of the ceramic substrate / the heat dissipation substrate to form a connection material layer includes: forming a coating on the sintered surface of the ceramic substrate / the heat dissipation substrate; A connection material is coated on the sintered surface of the ceramic substrate / the heat dissipation substrate on which the plating layer is formed to form a connection material layer, wherein the plating layer is a silver plating layer, a nickel plating layer, a copper plating layer or a titanium plating layer.

4. The sintering method according to claim 1, characterized in that: Applying a connection material on the sintering surface of the ceramic substrate / the heat dissipation substrate to form a connection material layer includes: The connection material is coated on the sintering surface of the ceramic substrate / the heat dissipation substrate by using a steel screen printing method or a dispensing coating method to form a connection material layer.

5. The sintering method according to claim 1, characterized in that: In the step of coating the connection material on the sintering surface of the ceramic substrate / the heat dissipation substrate to form a connection material layer, the coating thickness is between 10 μm and 800 μm.

6. The sintering method according to claim 1, characterized in that: In the step of coating a connection material on the sintering surface of the ceramic substrate / the heat dissipation substrate to form a connection material layer, the connection material is a sintered silver paste or a sintered copper paste.

7. The sintering method according to claim 1, characterized in that: The distance between each independent partition is between 1mm-10mm.

8. The sintering method according to claim 1, characterized in that: The ceramic substrate is a copper-clad ceramic substrate that is packaged in the power module and has a sintered surface exposed, or a copper-clad ceramic substrate that is not packaged in the power module.

9. The sintering method according to any one of claims 1 to 8, characterized in that: The boundary of each independent partition avoids the etching groove on the inner metal layer of the ceramic substrate.

10. A sintering method, applied to the interconnection between a ceramic substrate and a heat dissipation substrate of a power device, wherein the power device comprises a plurality of chips, characterized in that: The sintering method comprises: Coating a connection material on the sintered surfaces of the ceramic substrate and the heat dissipation substrate respectively to form a connection material layer, wherein the connection material layer includes a plurality of independent partitions, and the position of each independent partition corresponds to the position of at least one chip of the power device, and the connection material of at least one independent partition is coated on the connection surface of the ceramic substrate, and the connection materials of other independent partitions are coated on the connection surface of the heat dissipation substrate; Mounting the ceramic substrate coated with the connection material and the heat dissipation substrate to form a to-be-sintered component; The sintered part is subjected to pressure sintering to complete the connection between the ceramic substrate and the heat dissipation substrate.

11. A power device, characterized in that: The ceramic substrate and the heat dissipation substrate of the power device are interconnected by using the method described in any one of claims 1-10.

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