Power module with high reliability and high outflow capacity

Abstract

The invention provides the power module with high reliability and high outflow capacity. The power module comprises at least one power unit, and the power unit is provided with a radiator, a copper-clad ceramic substrate, a silicon-based chip and a connecting layer which are sequentially stacked along a first direction. The substrate is electrically connected with the chip and conducts heat with the radiator, and the chip conducts heat with the radiator through the substrate; the connecting layer is electrically connected with the chip, has conductivity and bonding performance, and is electrically connected with other parts through the connecting piece, so that the chip is electrically connected with the other parts through the connecting layer and the connecting piece. The high heating area of the bonding point on the upper surface of the chip is transferred to the surface of the connecting layer through the connecting layer, the chip failure is avoided, the high outflow capacity and the high reliability are achieved, and the connecting layer serves as an intermediate medium and provides a platform for follow-up fine design.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of new energy vehicles, and in particular to a power module with high reliability and high outflow capacity. BACKGROUND

[0002] As a core component of the electric drive system of new energy vehicles, the performance of the power module directly affects the efficiency and reliability of the vehicle. A typical power unit includes, from bottom to top, a heat sink, an insulating substrate, and IGBT (Insulated Gate Bipolar Transistor) and FRD (Fast Recovery Diode) chips carried thereon, and the electrodes of the chips are electrically interconnected with the substrate circuit through bonding wires. This layered structure collectively undertakes the key tasks of large current on-off and heat dissipation.

[0003] With the advancement of semiconductor technology, the ability of silicon-based power chips to withstand high temperatures has been significantly improved. However, the temperature bottleneck within the module has gradually shifted from the inside of the chip to its interconnection structure, particularly around the bonding points of the traditional bonding wires and chips. When a large current flows through the bonding wires, significant concentrated Joule heat is easily generated at this point. On the one hand, the high temperature at this point can cause chip failure, limiting the outflow capacity; on the other hand, more critically, the difference in the thermal expansion coefficient between the bonding wires and the chips can cause alternating stress under rapid temperature changes, leading to fatigue, cracking, and even shedding of the bonding points, thereby damaging the chips. This variety of failure modes caused by local overheating and thermal mechanical stress has become a key factor restricting the performance of silicon-based chips and limiting the overall outflow capacity of the module.

[0004] In summary, there is currently no power module that can operate stably at a high current outflow. SUMMARY

[0005] In order to overcome the above technical defects, the purpose of the present application is to provide a power module with high reliability and high outflow capacity.

[0006] The present application discloses a power module with high reliability and high outflow capacity.

[0007] The power module comprises at least one power unit; the at least one power unit comprises, in sequence from bottom to top, a heat sink, a substrate, a chip, and a connection layer; The substrate is a copper-clad ceramic substrate, electrically connected to the chip and thermally conductive with the heat sink; The chip is a silicon-based chip, thermally conductive with the heat sink through the substrate; The connecting layer is electrically connected with the chip; the connecting layer has conductivity and bondability and is electrically connected with other components through the connecting member; so that the chip can be electrically connected with other components through the connecting layer and the connecting member.

[0008] Preferably, the material of the connecting layer comprises at least one of tungsten-copper alloy, molybdenum-copper alloy and aluminum-based silicon carbide composite material.

[0009] Preferably, the connecting layer and the chip are fixedly connected through soldering of tin-based material or lead-based material.

[0010] Preferably, the connecting layer and the chip are fixedly connected through sintering of sintering material, and the sintering material comprises at least one of silver sintering material and copper sintering material.

[0011] Preferably, the projection of the connecting layer in the first direction covers more than 50% of the area of the chip; and the shape of the connecting layer comprises at least one of a circle, a square and an ellipse.

[0012] Preferably, the thickness of the connecting layer in the first direction is 0.05mm-2mm.

[0013] Preferably, the connecting member comprises at least one of copper wire, aluminum strip and copper strip.

[0014] Preferably, the power module comprises a plurality of power units.

[0015] Preferably, the plurality of connecting layers corresponding to the plurality of power units are integrally formed as an integral structure; and the connecting member is integrated in the connecting layer.

[0016] Preferably, the power module is a silicon-based insulated gate bipolar transistor type power module or a silicon-based fast recovery diode power module.

[0017] After the above technical scheme is adopted, the following beneficial effects are obtained compared with the prior art: 1. By additionally providing the connecting layer with conductivity and bondability above the chip, the fundamental effect is that the high heat generation area of the bonding point on the upper surface of the chip in the traditional structure is effectively transferred to the surface of the connecting layer. Since the connecting layer itself does not involve the sensitive structure of the silicon-based chip, local overheating will not directly cause the chip to fail, thereby realizing high current-carrying capacity and high reliability of the module. Further, the connecting layer as an intermediate medium will not affect the working state of the chip, providing a key platform for subsequent fine design (for example, fine design of the connecting member); 2. By selecting specific materials such as tungsten-copper alloy, molybdenum-copper alloy or aluminum-based silicon carbide composite to make the connecting layer, the connecting layer can ensure certain electrical conductivity and bondability. It also has certain heat conduction capacity, which facilitates heat transfer while matching the thermal expansion coefficient of the chip, significantly reducing the thermal stress generated at the interface due to temperature cycling. This double advantage significantly inhibits the failure risk of the connecting layer itself and its interface with the chip and the connecting piece, ensuring the structural stability under high current. By reasonably setting the surface area, shape and thickness of the connecting layer, the uniform heating efficiency of the connecting layer on the chip can be optimized, and the overall volume of the power module can be controlled; 3. Further, due to the isolation effect of the connecting layer, the connecting piece can be selected as a copper connecting piece (such as a copper wire or a copper strip) to enhance the electrical conductivity, without considering the damage to the chip after thermal expansion of the copper wire, thereby significantly reducing the connection loss and improving the current carrying capacity. Alternatively, an aluminum connecting piece can also be selected to reduce costs. The design of integrating multiple power units improves the power density of the module. Further integrating the connecting layers of multiple power units into an integrated structure and optimizing the setting method of the connecting piece (such as a copper strip) therein not only simplifies the electrical interconnection, reduces parasitic parameters, and improves current balance, but more importantly, fundamentally reduces the number of independent interconnection points, effectively eliminating the failure risk of the traditional bonding point, a weak link, and significantly enhancing the stability and long-term operation reliability of the overall structure of the module; 4. This scheme is particularly suitable for power modules composed of silicon-based insulated gate bipolar transistors and fast recovery diodes. Such modules are the core of the electric drive system of new energy vehicles and work in high-frequency switching and high-current conditions, which are extremely sensitive to the electrical and thermal stress of the interconnection structure. The connecting layer structure provided by the present scheme and the supporting optimization measures successfully solve the common bottleneck problem of bonding point failure in such silicon-based power modules, fully release the temperature resistance potential of silicon-based chips, and ultimately meet the core requirements of new energy vehicles for high-current capacity, high reliability and compactness of power modules. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 Structure diagram of a power unit of the high-reliability and high-current-capacity power module provided by the present application; Figure 2 Connection relationship diagram of two power units of the high-reliability and high-current-capacity power module provided by the present application.

[0019] Reference signs: 100, power unit; 1, heat sink; 2, substrate; 3, chip; 4, connecting layer; 41, connecting piece; z, first direction. DETAILED DESCRIPTION

[0020] The advantages of the present application are further set forth in the description that follows, and will be appreciated by persons skilled in the art upon reading and understanding the attached figures and detailed description.

[0021] Exemplary embodiments are described herein with reference to the accompanying drawings, of which examples are shown. The following description, in conjunction with the drawings, relates to the preferred embodiments. Unless otherwise noted, like numerals in different drawings denote like or similar elements. The embodiments described in the following examples do not represent all of the embodiments consistent with the present disclosure. Instead, they are merely examples of apparatuses and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0022] The terminology used in the description of the present disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used in the description of the present disclosure and the appended claims, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It also will be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0023] It will be understood that, although the terms first, second, third, etc. can be used herein to describe various information, these terms are not intended to denote a temporal or chronological order. Rather, these terms are used only as a shorthand notation to first, second, third, etc. terms in describing various embodiments. For example, a first information can also be termed a second information, and similarly, a second information can also be termed a first information, without departing from the scope of the present disclosure. As used herein, the term "if' can be construed to mean "when" or "in response to determining" that a certain condition precedent has been satisfied or obtained, unless and except the context clearly indicates otherwise. In the description of the present disclosure, it should be understood that the terms "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate the orientation or positional relationship based on the orientation or position shown in the drawings, and are only used to facilitate the description of the present disclosure and simplify the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present disclosure.

[0024] In the description of the present disclosure, unless otherwise specified and limited, it should be noted that the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be a mechanical connection or an electrical connection, or a communication between two elements, or a direct connection, or an indirect connection through an intermediate medium, and the specific meaning of the above terms can be understood by those skilled in the art according to the specific circumstances.

[0025] In the following description, the suffixes such as "module", "part", or "unit" used for an element are merely intended for facilitating explanation of the present application and by itself do not have a specific meaning. Thus, "module" and "part" can be used in mixture.

[0026] Referring to Figure 1 , Figure 1 A schematic structural diagram of a power unit of a power module with high reliability and high outflow capacity provided by the present application.

[0027] As Figure 1 indicated, the present application provides a power module with high reliability and high outflow capacity. The power module comprises at least one power unit 100; the at least one power unit 100 comprises, in sequence along a first direction z, a heat sink 1, a substrate 2, a chip 3, and a connecting layer 4; The substrate 2 is a copper-clad ceramic substrate, is electrically connected with the chip 3, and conducts heat with the heat sink 1. The chip 3 is a silicon-based chip, conducts heat with the heat sink 1 through the substrate 2. The connecting layer 4 is electrically connected with the chip 3; the connecting layer 4 has electrical conductivity and bondability, and is electrically connected with other components through a connecting piece 41; so that the chip 3 can be electrically connected with other components through the connecting layer 4 and the connecting piece 41.

[0028] By additionally providing the connecting layer 4 with electrical conductivity and bondability above the chip 3, the fundamental effect is that the high-heat area concentrated on the bonding point on the upper surface of the chip 3 in the traditional structure is effectively transferred to the surface of the connecting layer 4. Since the connecting layer 4 itself does not involve the sensitive structure of the silicon-based chip 3, local overheating will not directly cause the chip 3 to fail, thereby realizing high outflow capacity and high reliability of the module. Further, the connecting layer 4 as an intermediate medium will not affect the working state of the chip 3, providing a key platform for subsequent fine design (for example, fine design of the connecting piece 41).

[0029] The above is a description of the basic concept of the present application, and the specific embodiments of the present application will be further described below with reference to the accompanying drawings.

[0030] As mentioned above, the connecting layer 4 can also be designed further to improve its heat conduction performance, etc.

[0031] Therefore, it can be understood that, first, the specific material of the connecting layer 4 is not limited.

[0032] In one possible implementation, the material of the connecting layer 4 includes at least one of tungsten-copper alloy, molybdenum-copper alloy, and aluminum-based silicon carbide composite material.

[0033] The connecting layer 4 is made of tungsten-copper alloy, molybdenum-copper alloy or aluminum-based silicon carbide composite material, so that the connecting layer 4 has certain electrical conductivity and bondability, and has certain heat conduction capacity, so that heat can be transferred, the thermal expansion coefficient is matched with the chip 3, and the thermal stress generated at the interface due to temperature cycles is greatly weakened. The double advantages significantly inhibit the failure risk of the connecting layer 4 and the interface between the connecting layer 4, the chip 3 and the connecting piece 41, and ensure the structural stability under high current.

[0034] In another possible implementation, the material of the connecting layer 4 can also be other materials in addition to the above materials. Those skilled in the art can freely choose according to needs and chip 3 characteristics, which are not limited herein.

[0035] Secondly, the fixing manner between the connecting layer 4 and the chip 3 is also not limited.

[0036] In one possible implementation, the connecting layer 4 and the chip 3 are fixedly connected by soldering a tin-based material or a lead-based material.

[0037] In another possible implementation, the connecting layer 4 and the chip 3 are fixedly connected by sintering sintering material, and the sintering material includes at least one of silver sintering material and copper sintering material.

[0038] Those skilled in the art can understand that the connection relationship between other components can also be applicable to the above-mentioned manner. For example, the chip 3 and the substrate 2, the substrate 2 and the heat sink 1, etc. can also be connected by the above-mentioned soldering or sintering manner.

[0039] Thirdly, the shape and size of the connecting layer 4 are also not limited.

[0040] In one possible implementation, the projection of the connecting layer 4 in the first direction z covers more than 50% of the area of the chip 3; and the shape of the connecting layer 4 includes at least one of a circular shape, a square shape and an elliptical shape.

[0041] By limiting the area of the projection of the connecting layer 4 covering the surface of the chip 3, the area available for heat exchange between the two can be expanded, and a larger contact area directly reduces the local density of current transmission and the interface contact resistance, thereby reducing the generation of Joule heat from the source; at the same time, the efficiency of heat diffusion from the chip 3 to the connecting layer 4 is significantly improved, and the excessive concentration of heat in the edge or center area of the chip 3 is avoided. By setting the connecting layer 4 to be a regular shape such as a circular shape, a square shape or an elliptical shape, the uniformity of current distribution and the heat flow path can be optimized, the distortion of electric field or thermal field caused by sharp corners is avoided, and the heat dissipation reliability and current uniformity are further improved.

[0042] Further, the thickness of the connecting layer 4 in the first direction z is 0.05mm-2mm.

[0043] By reasonably setting the thickness, on the one hand, the connection layer 4 can be prevented from being too thick, which leads to high cost and increases the overall size of the power module. On the other hand, the connection layer 4 can also be prevented from being too thin, which leads to poor heat dissipation and large deformation when heated. Therefore, by accurately designing the thickness, the connection layer 4 can have high heat dissipation and long-term structural integrity when carrying large current.

[0044] The above is a detailed description of the specific implementation of the connection layer 4. Those skilled in the art can understand that the specific material of the connecting piece 41 is also not limited.

[0045] Please refer to Figure 2 , Figure 2 The connection relationship diagram of the two power units of the high-reliability and high-outflow-capability power module provided by the present application is shown.

[0046] As Figure 2 indicated and understood in combination Figure 1 . In a possible implementation, the connecting piece 41 is a connecting piece including a copper wire, an aluminum strip, and a copper strip.

[0047] Here, the principle needs to be explained: in the prior art, the connecting piece 41 is often directly connected to the top of the chip 3. Therefore, in terms of material selection, the connecting piece 41 often adopts aluminum material. This is because the aluminum connecting piece 41 is less likely to cause damage to the chip 3 when deformed by heat. However, the aluminum connecting piece 41 has lower conductivity and weaker current-carrying capacity.

[0048] Therefore, because the connection layer 4 in the present application can isolate thermal stress outside the chip 3, a copper wire with high conductivity can be safely selected. Moreover, because the area available for electrical connection of the connection layer 4 is larger, a copper strip / aluminum strip with stronger current-carrying capacity can be further applied. This not only significantly reduces the resistance loss and heat generation of the connecting piece 41 itself, but also greatly improves the current transmission efficiency and directly enhances the overall current-carrying capacity of the module, which is particularly suitable for the instantaneous large-current working condition requirements of new energy vehicles.

[0049] Of course, in another possible implementation, the connecting piece 41 can also adopt an aluminum strip to adapt to some special settings, and those skilled in the art can design as needed, which is not limited by the present application.

[0050] The above is a description of the connecting piece 41 provided by the present application. The overall structure of the power module is described below.

[0051] Those skilled in the art can understand that the number of power units 100 included in the power module is not limited.

[0052] As Figure 2As shown, in one possible implementation, the power module includes a plurality of power units 100. By employing the foregoing structure in each power unit 100, it can be ensured that heat can be efficiently conducted out of the unit. Such a modular design enables power expansion without sacrificing the heat dissipation performance of the unit level, and the plurality of units can still maintain uniform temperature distribution when working together, avoiding local overheating as a system bottleneck, thereby supporting the power module to continuously and stably output a large current in high-power application scenarios such as new energy vehicles.

[0053] Further, the plurality of connection layers 4 corresponding to the plurality of power units 100 are of an integrated structure formed integrally; and the connecting pieces 41 are integrated in the connection layers 4.

[0054] The integrated connection layer 4 can simplify the number of parts and reduce production and processing costs. Embedding or integrating the connecting pieces 41 (such as copper strips) in the integrated structure can shorten the current path, enhance mechanical stability, and effectively increase the heat dissipation surface area.

[0055] Further integrating the connecting pieces 41 in the connection layers 4 enables the power module to be connected directly through the connection layers 4 without the connecting pieces 41, which on the one hand can further reduce the number of connection points, thereby reducing the probability of occurrence of the traditional bonding wire failure mode from the root, and significantly improving the overall reliability and power density of the module; on the other hand, the volume available for connection is also greatly increased, thereby greatly enhancing the current-carrying capacity, and further improving the current output capacity of the power module.

[0056] It should be noted that the type of power module to which the present application is applicable is also not limited. Exemplarily, the power module can be a silicon-based insulated gate bipolar transistor (IGBT) power module or a silicon-based fast recovery diode (FRD) power module.

[0057] In order for those skilled in the art to more clearly and intuitively understand the technical effects of the scheme provided by the present application, an embodiment is provided below for reference.

[0058] In one possible embodiment, in the on-state loss test, the power module is set to: junction temperature Tvj = 185 °C; IGBT collector current Ice / FRD forward current If = 450 A. The final result is that the IGBT saturation voltage drop Vcesat is 1.50 V. Compared with the scheme in the prior art, the test result under the same conditions is 1.63 V. The FRD forward conduction voltage drop FRDVF is 1.70 V, and in the prior art, it is 1.91 V. It can be seen that the on-state loss is significantly reduced.

[0059] In the stability test, the input DC voltage of the power module is Vdc=480V; the switching frequency is fsw=10kHz; the coolant flow rate is Frate=8L / min; the coolant temperature is Tcoolant=85℃; the power factor is PF=0; and the output AC frequency is fac=50Hz. The final result is that the maximum output current Ioutput of the power module reaches 550A without failure. The prior art solution provided under the same conditions fails at 430A. It can be seen that the outflow capacity is significantly increased, and the reliability is high.

[0060] In summary, the power module provided by the application has high reliability and high outflow capacity.

[0061] It should be noted that the embodiments of the application have better implementation, and do not limit the application in any form. Any skilled person in the art can change or modify the above disclosed technical content into equivalent effective embodiments without departing from the technical scheme of the application. Any modification or equivalent change and modification of the above embodiments according to the technical essence of the application still belongs to the scope of the technical scheme of the application.

Claims

1. A power module with high reliability and high current output capability, characterized in that, The power module includes at least one power unit; the at least one power unit includes a heat sink, a substrate, a chip, and a connection layer stacked sequentially along a first direction; The substrate is a copper-clad ceramic substrate, which is electrically connected to the chip and conducts heat with the heat sink; The chip is a silicon-based chip, and heat is conducted between the substrate and the heat sink. The connection layer is electrically connected to the chip; the connection layer is conductive and bondable, and is electrically connected to other components through connectors; so that the chip can be electrically connected to other components through the connection layer and the connectors.

2. The power module as described in claim 1, characterized in that, The material of the connecting layer includes at least one of tungsten copper alloy, molybdenum copper alloy, and aluminum-based silicon carbide composite material.

3. The power module as described in claim 2, characterized in that, The connection layer and the chip are fixedly connected by soldering with tin-based solder or lead-based solder.

4. The power module as described in claim 2, characterized in that, The connecting layer and the chip are fixedly connected by a sintering material, which includes at least one of silver sintering material and copper sintering material.

5. The power module as described in claim 1, characterized in that, The projection of the connection layer in the first direction covers more than 50% of the area of ​​the chip; and the shape of the connection layer includes at least one of the following: circular, square, and elliptical.

6. The power module as described in claim 1, characterized in that, The thickness of the connecting layer in the first direction is 0.05mm-2mm.

7. The power module as described in claim 1, characterized in that, The connector includes at least one of copper wire, aluminum strip, and copper strip.

8. The power module as described in claim 1, characterized in that, The power module includes multiple power units.

9. The power module as described in claim 8, characterized in that, The multiple connection layers corresponding to the multiple power units are integrally formed structures; the connectors are integrated within the connection layers.

10. The power module as described in claims 1-9, characterized in that, The power module is a silicon-based insulated gate bipolar transistor power module or a silicon-based fast recovery diode power module.

Images