A press-fit type IGBT power module based on functionally graded composite material packaging

Abstract

The present invention relates to a press-fit type IGBT power module encapsulated with gradient functional composite materials. The IGBT sub-module between the collector metal layer and the emitter metal layer includes a collector gradient functional composite material layer, an IGBT power chip, an emitter gradient functional composite material layer, a copper base, and a gate PCB board that are press-fitted in sequence from top to bottom. After press-fitting, the IGBT sub-module is sleeved with a packaging shell bracket. Gate spring thimbles are placed in the notches of the emitter gradient functional composite material layer and the copper base after press-fitting. The thermal expansion coefficients of the collector gradient functional composite material layer and the collector metal layer, the surface of the collector of the IGBT power chip, the emitter gradient functional composite material layer, the surface of the emitter of the IGBT power chip, and the copper base are matched, solving the problems of the decline in the electrothermal contact performance of the component interface, the reduction in heat dissipation efficiency, and the shortening of the device service life caused by the mismatch of the thermal expansion coefficients between the IGBT power chip and the packaging material components in the existing press-fit type IGBT power module.

Description

Technical Field

[0001] The present invention belongs to the field of power semiconductor devices, and relates to a press-pack IGBT power module based on a functionally graded composite material package. Background Art

[0002] Compared with the IGBT power module with a welded package structure, the IGBT power module with a press-pack package structure has the advantages of high power density, double-sided heat dissipation, low on-state loss, strong shock resistance, large current-carrying capacity, failure short circuit, and easy series connection. It is suitable for the application conditions of high-voltage and large-capacity power equipment such as MMC converters in flexible DC transmission systems. Using a smaller number of press-pack IGBT power modules can meet the voltage level and capacity requirements of MMC converters, effectively reducing the integration manufacturing and operation and maintenance difficulties of large-capacity power equipment, and having broad market and application prospects.

[0003] The schematic diagram of the package structure of a traditional press-pack IGBT power device is as Figure 1 shown, which is composed of seven layers of packaging materials. When the IGBT power chip works, the interface between each layer of packaging components realizes electrothermal conduction by relying on pressure contact. Due to the mismatch of the thermal expansion coefficients of the materials of each layer of components, the expansion and deformation of the IGBT power chip and the rigid packaging material are inconsistent when the device works, resulting in continuous contact friction and extrusion between the emitter surface of the IGBT power chip and the rigid component, making dents appear on the surface of the IGBT power chip, accelerating the fatigue failure process of the power device; and the mismatch of the thermal expansion coefficients causes the effective contact area between the components to gradually decrease under the action of alternating thermal stress, affecting the electrothermal conduction efficiency when the IGBT power device works, resulting in an increase in the contact resistance and contact thermal resistance of the device, an increase in working loss, a decrease in heat dissipation efficiency, and a shortening of the service life of the entire press-pack IGBT power module. Summary of the Invention

[0004] In view of this, in order to solve the problem that the mismatch of the thermal expansion coefficients between the IGBT power chip and the packaging material components in the existing press-pack IGBT power module leads to a gradual decrease in the effective contact area between the components under the action of alternating thermal stress, resulting in a decline in the electrothermal contact performance of the component interface, a decrease in heat dissipation efficiency, and a shortening of the service life of the device, the present invention provides a press-pack IGBT power module based on a functionally graded composite material package, realizing the best match of the thermal expansion coefficients between the IGBT power chip and the packaging material, improving the electrothermal conduction performance when the IGBT power device works, and extending the service life of the device.

[0005] To achieve the above object, the present invention provides the following technical solution: A press-fit type IGBT power module based on gradient functional composite material packaging, comprising a coaxially arranged collector metal layer and emitter metal layer, with an IGBT sub-module press-fitted between the collector metal layer and the emitter metal layer. The IGBT sub-module includes a collector gradient functional composite material layer, an IGBT power chip, an emitter gradient functional composite material layer, a copper base, and a gate PCB board, which are press-fitted in sequence from top to bottom. The shapes of the emitter gradient functional composite material layer and the copper base are both rectangular parallelepipeds with notches. After press-fitting, the IGBT sub-module is sleeved with a packaging housing bracket. A gate spring thimble is placed in the notches of the emitter gradient functional composite material layer and the copper base after press-fitting. The thermal expansion coefficients of the collector gradient functional composite material layer match those of the collector metal layer and the surface of the collector of the IGBT power chip respectively, and the thermal expansion coefficients of the emitter gradient functional composite material layer match those of the emitter surface of the IGBT power chip and the copper base respectively.

[0006] Furthermore, a press-fit type IGBT power module based on gradient functional composite material packaging, comprising a coaxially arranged collector metal layer and emitter metal layer, with a plurality of parallel-connected IGBT sub-modules press-fitted between the collector metal layer and the emitter metal layer. A ring of Diode sub-modules, that is, reverse freewheeling diodes without cut corners, is installed on the emitter metal layer outside the parallel-connected IGBT sub-modules. The IGBT sub-module includes a collector gradient functional composite material layer, an IGBT power chip, an emitter gradient functional composite material layer, a copper base, and a gate PCB board, which are press-fitted in sequence from top to bottom. The shapes of the emitter gradient functional composite material layer and the copper base are both rectangular parallelepipeds with notches. After press-fitting, the emitter gradient functional composite material layer and the copper base are sleeved with a packaging housing bracket. A gate spring thimble is placed in the notches of the emitter gradient functional composite material layer and the copper base after press-fitting. Gate drive terminals are led out from the gate PCB board, and the gate PCB boards of each IGBT sub-module are connected through the gate drive terminals. The external drive circuit transmits signals through the gate drive terminals, and after passing through the PCB board and the gate spring thimble, controls the on-off of the IGBT sub-module. The thermal expansion coefficients of the collector gradient functional composite material layer match those of the collector metal layer and the surface of the collector of the IGBT power chip respectively, and the thermal expansion coefficients of the emitter gradient functional composite material layer match those of the emitter surface of the IGBT power chip and the copper base respectively.

[0007] Furthermore, the difference in thermal expansion coefficients between the collector gradient functional composite material layer and the collector metal layer and the surface of the collector of the IGBT power chip is within 5%; the difference in thermal expansion coefficients between the emitter gradient functional composite material layer and the emitter surface of the IGBT power chip and the copper base is within 5%.

[0008] Furthermore, the material hardness of the side of the collector gradient functional composite material layer in contact with the surface of the collector of the IGBT power chip is the same; the material hardness of the side of the emitter gradient functional composite material layer in contact with the surface of the emitter of the IGBT power chip is the same.

[0009] Furthermore, both the collector metal layer and the emitter metal layer are cylindrical and are made of materials with high electrical conductivity and high thermal conductivity. Beneficial effects: The collector metal layer and the emitter metal layer serve as the connection medium between the IGBT power device and the radiator, playing a role in fastening the packaging components and providing support. Their sizes are determined by the current-carrying capacity of the IGBT power module.

[0010] Furthermore, the upper end of the gate spring thimble is connected to the IGBT power chip, and the lower end is connected to the gate PCB board. It is a cylinder with a diameter of 2 mm, and both ends are hemispherical arcs.

[0011] The beneficial effects of the present invention are as follows:

[0012] 1. The press-packaged IGBT power module based on gradient functional composite material packaging disclosed in the present invention reduces the number of component layers of the packaging material of the traditional press-packaged IGBT power module from 7 layers to 6 layers, reducing the packaging integration difficulty, shortening the electrical and thermal conduction paths during device operation, greatly improving the electrothermal performance of the IGBT power device during operation, and significantly enhancing the heat dissipation efficiency.

[0013] 2. The press-packaged IGBT power module based on gradient functional composite material packaging disclosed in the present invention achieves an optimal matching state of the thermal expansion coefficients among the gradient functional composite material, the IGBT power chip, the collector metal material, and the emitter metal material components, effectively curbing the problem that the difference in thermal expansion deformation among components gradually expands under the action of alternating thermal stress, resulting in a reduction in the effective contact area, and keeping the electrothermal contact performance between the interfaces of the IGBT power device components in a good state all the time.

[0014] 3. In the press-packaged IGBT power device with the traditional packaging structure, under the action of alternating thermal stress, the surface of the emitter of the chip will come into contact and friction with the rigid component, generating indentations, which will accelerate the fatigue failure of the device. The emitter gradient functional composite material adopted in the present invention has the same material hardness as the surface of the emitter of the IGBT power chip, achieving the best matching of the thermal expansion coefficients between the IGBT power chip and the packaging material, effectively eliminating the problem of indentations generated by the friction between the IGBT power chip and the rigid component, delaying the aging failure rate of the IGBT power device, and improving the service life of the device.

[0015] Other advantages, objects and features of the present invention will be set forth in part in the following description, and in part will be obvious to those skilled in the art upon examination of the following, or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained by the following description of the specification. Brief Description of the Drawings

[0016] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in detail preferably with reference to the accompanying drawings, wherein:

[0017] Figure 1 It is a schematic diagram of the packaging structure of a traditional press-fit type IGBT power device;

[0018] Figure 2 It is a schematic diagram of the packaging structure of a single device of a press-fit type IGBT power module based on gradient functional composite material packaging of the present invention;

[0019] Figure 3 For the present invention Figure 2 It is a schematic diagram of the structure of the IGBT power chip in the present invention;

[0020] Figure 4 For the present invention Figure 2 It is a schematic diagram of the structures of the collector gradient functional composite material layer, the IGBT power chip, and the emitter gradient functional composite material layer in the present invention;

[0021] Figure 5 It is a schematic diagram of the structure of a press-fit type IGBT power module formed by paralleling press-fit type IGBT power devices based on gradient functional composite material packaging of the present invention.

[0022] Reference numerals: collector copper layer 1, collector molybdenum layer 2, IGBT power chip 3, emitter gate of IGBT power chip 31, emitter active region of IGBT power chip 32, collector of IGBT power chip 33, emitter of IGBT power chip 34, gate spring thimble 4, emitter molybdenum layer 5, emitter silver gasket 6, packaging housing bracket 7, copper base 8, gate PCB board 9, emitter copper layer 10, collector metal layer 11, collector gradient functional composite material layer 12, emitter gradient functional composite material layer 13, emitter metal layer 14, IGBT sub-module 15, reverse freewheeling diode 16. Detailed Embodiments

[0023] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand the other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the drawings provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0024] Among them, the drawings are only for illustrative purposes, showing only schematic diagrams, not physical diagrams, and should not be construed as a limitation on the present invention; in order to better illustrate the embodiments of the present invention, some components in the drawings will be omitted, enlarged or reduced, which does not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0025] In the drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and should not be construed as a limitation on the present invention. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0026] As Figure 1 shown, a traditional press-fit type IGBT power module includes a coaxially arranged collector copper layer and emitter copper layer. One IGBT sub-module is press-fitted between the collector copper layer 1 and the emitter copper layer 10.

[0027] The IGBT sub-module includes a collector molybdenum layer 2, an IGBT power chip 3, an emitter molybdenum layer 5, an emitter silver gasket 6, a copper base 8, and a gate PCB board 9 that are press-fitted in sequence from top to bottom. The emitter molybdenum layer 5, the emitter silver gasket 6, and the copper base 8 are all in the shape of a cuboid with a notch. After press-fitting, the collector molybdenum layer 2, the IGBT power chip 3, the emitter molybdenum layer 5, the emitter silver gasket 6, and the copper base 8 are sleeved with a packaging housing bracket 7. A gate spring thimble 4 is placed in the notch of the emitter molybdenum layer 5, the emitter silver gasket 6, and the copper base 8 after press-fitting.

[0028] As Figures 2 to 5A crimped IGBT power module based on functionally graded material (FGM) encapsulation is shown, which includes a coaxially arranged collector metal layer 11 and an emitter metal layer 14. A number of IGBT sub-modules connected in parallel are crimped between the collector metal layer 11 and the emitter metal layer 14. The collector metal layer is cylindrical and made of materials with high electrical conductivity and high thermal conductivity such as copper or aluminum. As the connection medium between the IGBT power device and the radiator, it plays a role in fastening the encapsulation components and providing support. Its size is determined by the current-carrying capacity of the IGBT power module and can be calculated as 8mm 2 / A; the emitter metal layer is also cylindrical and made of materials with high electrical conductivity and high thermal conductivity such as copper or aluminum, and its size is the same as that of the collector metal material layer.

[0029] Figure 2 As shown, there is 1 IGBT sub-module 15 crimped between the collector metal layer and the emitter metal layer. Figure 5 As shown, there are a number of IGBT sub-modules connected in parallel crimped between the collector metal layer and the emitter metal layer. Each IGBT sub-module is connected through a gate PCB board and then led out to the gate drive terminal of the entire IGBT power module. A ring of Diode sub-modules, that is, a non-cutoff reverse freewheeling diode 16, is installed on the emitter metal layer outside the parallel-connected IGBT sub-modules.

[0030] The IGBT sub-module includes a collector functionally graded material layer 12, an IGBT power chip 3, an emitter functionally graded material layer 13, a copper base 8, and a gate PCB board 9 crimped in sequence from top to bottom. The shapes of the emitter functionally graded material layer 13 and the copper base 8 are both rectangular parallelepipeds with notches. After crimping, the collector functionally graded material layer 12, the IGBT power chip 3, the emitter functionally graded material layer 13, and the copper base 8 are sleeved with an encapsulation housing bracket 7. After crimping, a gate spring thimble 4 is placed in the notch of the emitter functionally graded material layer 13 and the copper base 8.

[0031] The collector functionally graded material layer 12 is made of a new composite material, which is respectively matched with the thermal expansion coefficients of the collector metal layer and the surface of the collector of the IGBT power chip, and its shape is the same as the size of the IGBT power chip; the collector functionally graded material layer is used to connect the collector metal layer and the IGBT power chip, and the IGBT power chip and the collector metal layer are connected by the functionally graded material of the collector functionally graded material layer.

[0032] The gate spring thimble 4 is made of copper and is placed directly below the emitter gate 31 area of the IGBT power chip. After the IGBT sub-module is crimped, the upper end is connected to the IGBT power chip and the lower end is connected to the gate PCB board. Its size is a cylinder with a diameter of 2mm, and both ends are hemispherical arcs.

[0033] The emitter gradient functional composite material layer 13 is made of a new composite material, which is respectively matched with the thermal expansion coefficients of the emitter surface of the IGBT power chip and the copper base. It is in the shape of a rectangular cuboid with a notch at one corner. The length and width correspond to the size of the active area of the IGBT power chip, and the length and width at the notch are slightly larger than the diameter of the spring pogo pin.

[0034] The copper base 8 is a rectangular cuboid with a notch at one corner. Its shape is the same as the size of the emitter active area 32 of the IGBT power chip, and the notch size is slightly larger than the diameter of the spring pogo pin.

[0035] Gate drive terminals are led out on the gate PCB board 9. The gate PCB boards of each IGBT sub-module are connected through the gate drive terminals. The external drive circuit transmits signals through the gate drive terminals and controls the on-off of the IGBT sub-module after passing through the PCB board and the gate spring pogo pin. The gate PCB board is the medium for connecting the IGBT power chip, the gate spring pogo pin and the external drive signal.

[0036] The gate region of the IGBT power chip 3 is connected to the PCB board via the gate spring pogo pin and then connected to the gate drive terminal of the module. The area of the chip active region is equal to the area of the emitter gradient functional composite material. The collector gradient functional composite material layer 12 is composed of multiple materials and has high conductivity and high thermal conductivity. The material on the side in contact with the collector surface of the IGBT power chip has the same hardness as the material on the collector surface of the IGBT power chip 33, and the difference in thermal expansion coefficient from the material on the collector surface of the IGBT power chip 33 is within 5%. The difference in thermal expansion coefficient between the material in contact with the surface of the collector metal layer and the gradient functional composite material layer is within 5%.

[0037] The emitter gradient functional composite material layer 13 is composed of multiple materials and has high conductivity and high thermal conductivity. The material on the side in contact with the emitter surface of the IGBT power chip has the same hardness as the material on the emitter 34 surface of the IGBT power chip, and the difference in thermal expansion coefficient from the material on the emitter 34 surface of the IGBT power chip is within 5%. The difference in thermal expansion coefficient between the material in contact with the surface of the copper base and copper is within 5%.

[0038] The gate PCB board 9 is the carrier of the gate spring pogo pin of the IGBT power chip and the external drive control circuit. The drive signal transmitted by the gate PCB board controls the on-off of the IGBT power chip via the gate spring pogo pin.

[0039] 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. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the present technical solution, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A press-fit type IGBT power module encapsulated with gradient functional composite materials, characterized in that It includes a coaxially arranged collector metal layer and emitter metal layer. An IGBT sub-module is press-fitted between the collector metal layer and the emitter metal layer. The IGBT sub-module includes a collector gradient functional composite layer, an IGBT power chip, an emitter gradient functional composite layer, a copper base, and a gate PCB board that are press-fitted in sequence from top to bottom. The shapes of the emitter gradient functional composite layer and the copper base are both rectangular cuboids with notches. After press-fitting, the IGBT sub-module is sleeved with a packaging housing bracket. Gate spring thimbles are placed in the notches of the emitter gradient functional composite layer and the copper base after press-fitting. The thermal expansion coefficients of the collector gradient functional composite layer match those of the collector metal layer and the surface of the collector of the IGBT power chip respectively. The thermal expansion coefficients of the emitter gradient functional composite layer match those of the emitter surface of the IGBT power chip and the copper base respectively; The material hardness of the side of the collector gradient functional composite layer in contact with the collector surface of the IGBT power chip is the same; the material hardness of the side of the emitter gradient functional composite layer in contact with the emitter surface of the IGBT power chip is the same; The difference in thermal expansion coefficients between the collector gradient functional composite layer and the collector metal layer and the surface of the collector of the IGBT power chip is within 5%; the difference in thermal expansion coefficients between the emitter gradient functional composite layer and the emitter surface of the IGBT power chip and the copper base is within 5%.

2. A press-fit type IGBT power module encapsulated with gradient functional composite materials, characterized in that, It includes a coaxially arranged collector metal layer and emitter metal layer. A number of parallel-connected IGBT sub-modules are press-fitted between the collector metal layer and the emitter metal layer. A ring of Diode sub-modules, that is, a non-cutoff reverse freewheeling diode, is installed on the emitter metal layer outside the parallel-connected IGBT sub-modules. The IGBT sub-module includes a collector gradient functional composite layer, an IGBT power chip, an emitter gradient functional composite layer, a copper base, and a gate PCB board that are press-fitted in sequence from top to bottom. The shapes of the emitter gradient functional composite layer and the copper base are both rectangular cuboids with notches. After press-fitting, the emitter gradient functional composite layer and the copper base are sleeved with a packaging housing bracket. Gate spring thimbles are placed in the notches of the emitter gradient functional composite layer and the copper base after press-fitting. Gate drive terminals are led out from the gate PCB board. The gate PCB boards of each IGBT sub-module are connected through the gate drive terminals. The external drive circuit transmits signals through the gate drive terminals, and after passing through the PCB board and the gate spring thimbles, controls the on-off of the IGBT sub-module. The thermal expansion coefficients of the collector gradient functional composite layer match those of the collector metal layer and the surface of the collector of the IGBT power chip respectively. The thermal expansion coefficients of the emitter gradient functional composite layer match those of the emitter surface of the IGBT power chip and the copper base respectively; The material hardness of the side of the collector gradient functional composite layer in contact with the collector surface of the IGBT power chip is the same; the material hardness of the side of the emitter gradient functional composite layer in contact with the emitter surface of the IGBT power chip is the same; The difference in the coefficient of thermal expansion between the collector gradient functional composite material layer and the collector metal layer and the surface of the IGBT power chip collector is within 5%; the difference in the coefficient of thermal expansion between the emitter gradient functional composite material layer and the emitter surface of the IGBT power chip and the copper base is within 5%.

3. The crimped IGBT power module according to claim 1 or 2, characterized in that Both the collector metal layer and the emitter metal layer are cylindrical and are made of materials with high conductivity and high thermal conductivity.

4. The crimped IGBT power module according to claim 1 or 2, wherein The upper end of the gate spring thimble is connected to the IGBT power chip, and the lower end is connected to the gate PCB board. It is a cylinder with a diameter of 2 mm, and both ends are hemispherical arcs.

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