A curved surface design method of a power module bottom plate

Abstract

The application discloses a curved surface design method of a power module bottom plate. The method comprises the following steps: performing bimodal Gaussian distribution curvature design on a long-side cross-section profile of the power module bottom plate; performing circular arc curve design on a short-side cross-section profile of the power module bottom plate; and attaching the designed power module to a heat sink of a power conversion system. By implementing the method, interface cavities can be effectively reduced, heat conduction efficiency and mechanical stability can be improved, and problems existing in the prior art, such as high contact thermal resistance and poor thermal mechanical reliability, can be solved.

Description

Technical Field

[0001] This invention relates to the field of power module technology, and in particular to a method for designing the curved surface of a power module base plate. Background Technology

[0002] In modern power electronic systems, power modules, as core components, play a crucial role. They not only need to possess extremely high current-carrying capacity to ensure efficient power transmission, but also require excellent operational reliability to operate stably under long-term, high-load conditions. Power modules are typically integrated into a single package, including semiconductor components such as IGBTs and MOSFETs, a substrate, a heat sink, and external connection terminals.

[0003] A tight connection between the power module baseplate and the heatsink is crucial for efficient heat transfer. However, in practical applications, due to manufacturing limitations or design flaws, tiny interface cavities often appear between the baseplate and the heatsink. These cavities significantly increase contact thermal resistance, thus affecting the overall system's heat dissipation efficiency. Contact thermal resistance is a significant component of total thermal resistance, accounting for over 50%, therefore its optimization is crucial for improving the overall performance of the power module.

[0004] To reduce contact thermal resistance, existing technologies primarily involve reducing package thickness and using high thermal conductivity materials. While these methods can improve heat conduction to some extent and reduce interfacial cavities, they may lead to a decrease in the mechanical strength of the package structure, thus affecting the long-term reliability of the module. Although they can improve heat conduction efficiency, these materials are expensive and may, in some cases, sacrifice other performance aspects, such as electrical insulation or manufacturing complexity. Furthermore, system thermal resistance is mainly determined by the design and structure of the power conversion system and cannot be changed by optimizing the power module itself. This means that even if the internal design of the power module is improved, the overall system thermal management performance may still be limited by external factors.

[0005] Therefore, it is necessary to design a new method to effectively reduce interface cavities, improve heat conduction efficiency and mechanical stability, and solve problems such as high contact thermal resistance and poor thermomechanical reliability in existing technologies. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a curved surface design method for a power module base plate.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a curved surface design method for a power module base plate, comprising:

[0008] The long-side cross-sectional profile of the power module base plate is designed with a bimodal Gaussian curvature.

[0009] The short-side cross-sectional profile of the power module base plate adopts a circular arc curve design;

[0010] The designed power module is then attached to the heat sink of the power conversion system.

[0011] The further technical solution is as follows: the height difference between the center symmetry point and the edge point of the long side cross-sectional profile of the power module base plate is defined as the longitudinal arc height, and the longitudinal arc height is not greater than 550μm.

[0012] The further technical solution is as follows: the height difference between the center symmetry point and the edge point of the short side cross-sectional profile of the power module base plate is defined as the lateral arc height, and the lateral arc height is not greater than 75μm.

[0013] The further technical solution is as follows: For the long side cross-sectional profile of the power module base plate, on the line segment formed by connecting the center point and the edge point of the long side cross-section, at the peak point of the curvature of the long side cross-sectional profile curve of the power module base plate, a vertical line segment is connected to the curve. The distance between the vertical line segment and the curve at the peak point of curvature is defined as the characteristic arc height, and the characteristic arc height is not greater than 85μm.

[0014] The further technical solution is as follows: the distance from the vertical line segment to the central symmetrical point is defined as the peak curvature position, and the peak curvature position is no greater than 30mm.

[0015] The further technical solution is as follows: the curvature distribution function corresponding to the long side cross-sectional profile of the power module base plate is: (x)=κmax[exp(-β(xP(d))²)+exp(-β(x+P(d))²)], where κmax is the maximum curvature, x is the horizontal coordinate, β is the curvature concentration, and there are no curvature abrupt inflection points on the curve that affect the curvature concentration; P(d) is the position of the peak curvature. (x) is the curvature distribution function.

[0016] The further technical solution is as follows: fasteners are also installed on the power module base plate; the fasteners are tightened symmetrically at four points.

[0017] The further technical solution is as follows: the power module base plate is provided with a locking hole, the diameter of which is 5mm to 9mm.

[0018] The further technical solution is as follows: the diameter of the fastener is 4mm to 8mm, and the torque is 2.0N·m to 4.5N·m.

[0019] The further technical solution is as follows: the thickness of the thermal interface material used in the heat sink is 100μm to 200μm, and the thermal conductivity is not less than 2.0W / m·K.

[0020] The advantages of this invention compared to existing technologies are as follows: By designing the long side cross-sectional profile as a bimodal Gaussian distribution curve and the short side cross-sectional profile as a circular arc curve, this invention achieves a tighter and smoother contact between the base plate and the heat sink, effectively reducing the presence of interface cavities and thus improving heat transfer efficiency. Furthermore, by combining optimized locking techniques such as the four-point symmetrical tightening method, it ensures uniform pressure distribution during installation, enhancing mechanical stability and preventing deformation or damage caused by localized stress concentration. This method solves the problems of high contact thermal resistance and poor thermomechanical reliability commonly found in existing technologies, providing a solution that significantly improves heat dissipation performance and reliability without additional cost.

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 A flowchart illustrating a curved surface design method for a power module base plate provided in an embodiment of the present invention;

[0024] Figure 2 A schematic diagram of the characteristic curvature parameters of the long side cross-sectional profile curve provided in an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the characteristic curvature parameters of the cross-sectional profile curve of the base plate short plate provided in an embodiment of the present invention;

[0026] Figure 4 This is a schematic diagram of the power module and latching method provided in an embodiment of the present invention. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0029] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0030] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0031] Please see Figure 1 , Figure 1 This is a schematic flowchart illustrating a curved surface design method for a power module base plate provided in an embodiment of the present invention. This method achieves fine adjustment of the base plate's surface morphology by precisely controlling the bimodal Gaussian curvature of the long side cross-section profile and the circular arc curve design of the short side cross-section profile. This effectively reduces the cavity at the interface with the heat sink, thereby improving heat conduction efficiency. The method defines key geometric parameters such as longitudinal arc height, transverse arc height, and characteristic arc height, and strictly limits their maximum values ​​to ensure good fit between the base plate and the heat sink, reducing contact thermal resistance. Furthermore, a four-point symmetrical tightening method is used to fix the fasteners, further enhancing mechanical stability and thermomechanical reliability. Simultaneously, the selection of appropriate locking hole diameters and fastener specifications ensures stability and consistency during installation. For the heat sink, a thermal interface material with excellent thermal conductivity is selected, and its thickness is controlled within the range of 100μm to 200μm, further optimizing the heat conduction path and solving the problems of high contact thermal resistance and poor thermomechanical reliability in existing technologies. Overall, this improves the performance and stability of the power conversion system.

[0032] Figure 1 This is a flowchart illustrating the curved surface design method for the power module base plate provided in an embodiment of the present invention. Figure 1 As shown, the method includes the following steps S110 to S130.

[0033] S110. Design the bimodal Gaussian curvature of the long side cross-sectional profile of the power module base plate.

[0034] In this embodiment, the height difference between the center symmetry point and the edge point of the short side cross-sectional profile of the power module base plate is defined as the lateral arc height, which is no greater than 75μm.

[0035] For the long side cross-sectional profile of the power module base plate, on the line segment connecting the center point and the edge point of the long side cross-section, at the peak point of the curvature of the long side cross-sectional profile curve of the power module base plate, a vertical line segment is connected to the curve. The distance between the vertical line segment and the curve at the peak point of curvature is defined as the characteristic arc height, which is not greater than 85μm.

[0036] The distance from the vertical line segment to the central symmetrical point is defined as the peak curvature position, which is no greater than 30mm.

[0037] The curvature distribution function corresponding to the long side cross-sectional profile of the power module base plate is: (x)=κmax[exp(-β(xP(d))²)+exp(-β(x+P(d))²)], where κmax is the maximum curvature, x is the horizontal coordinate, β is the curvature concentration, and there are no curvature abrupt inflection points on the curve that affect the curvature concentration; P(d) is the position of the peak curvature. (x) is the curvature distribution function.

[0038] In this embodiment, the long-side cross-sectional profile of the power module base plate is designed with a bimodal Gaussian curvature. The core of this design method lies in precisely controlling the surface morphology of the base plate to optimize its contact quality with the heat sink, thereby improving heat conduction efficiency and enhancing mechanical stability.

[0039] like Figure 2 and Figure 3 As shown, firstly, for the long-side cross-sectional profile of the power module base plate, the height difference between its central symmetry point and edge point is defined as the longitudinal arc height, which does not exceed 550μm. This parameter ensures that the base plate can effectively adhere to the heat sink, reducing the existence of interface cavities and thus lowering contact thermal resistance.

[0040] Secondly, for the short-side cross-sectional profile, a circular arc curve design is adopted, with the height difference between the central symmetry point and the edge point defined as the lateral arc height, and the maximum value limited to within 75μm. This further enhances the tightness and consistency between the base plate and the heat sink, contributing to uniform heat distribution.

[0041] Next, during the design of the long-side cross-sectional profile, a line segment is formed by connecting the center point and the edge point. At the peak of curvature, this line segment is extended to the curve using a vertical line. The vertical distance between the two segments is measured as the characteristic arc height, which should not exceed 85 μm. Furthermore, the distance from the vertical line segment to the center symmetry point is defined as the peak curvature location, and it must not exceed 30 mm. Precise control of these geometric parameters is crucial for achieving efficient heat conduction.

[0042] Finally, the expression for the curvature distribution function corresponding to the long side cross-sectional profile is: (x) = κmax[exp(-β(xP(d))²) + exp(-β(x+P(d))²)], where κmax represents the maximum curvature, x represents the lateral coordinate, β is the curvature concentration, and P(d) is the location of the peak curvature (in millimeters). Specifically, this curve should not contain any curvature abrupt inflection points that affect β, to ensure the continuity and stability of the curvature distribution, which is crucial for maintaining good thermal conductivity.

[0043] In summary, by meticulously designing the cross-sectional profiles of the long and short sides and strictly controlling relevant geometric parameters, the method proposed in this invention not only significantly reduces interface cavities and improves heat conduction efficiency but also enhances mechanical stability, solving problems such as high contact thermal resistance and poor thermomechanical reliability in existing technologies. Furthermore, this method requires no additional cost investment and possesses high practical value and application prospects.

[0044] S120. The short side cross-sectional profile of the power module base plate adopts a circular arc curve design.

[0045] In this embodiment, the height difference between the center symmetry point and the edge point of the long side cross-sectional profile of the power module base plate is defined as the longitudinal arc height, which is no greater than 550μm.

[0046] The use of a circular arc curve in the short-side cross-sectional profile is a crucial element. This design aims to optimize the contact quality between the power module and the heat sink, thereby effectively reducing interface cavities, minimizing contact thermal resistance, and improving overall heat dissipation efficiency and mechanical stability.

[0047] The short-side cross-sectional profile of the module base plate is composed of circular arc segments, and the height difference between its central symmetrical point and edge point is defined as the lateral arc height (HS). Figure 3 As shown.

[0048] The maximum value of the lateral arc height HS should not exceed 75μm. This limitation ensures that the base plate can fit tightly against the heat sink, minimizing the interface cavity.

[0049] The arc-curve design allows the base plate to naturally adapt to the slight unevenness of the heat sink surface during the locking process, thereby ensuring a more uniform pressure distribution and better heat conduction.

[0050] In special cases, when the curvature is zero, the circular arc degenerates into a straight line, which means that the design has a certain degree of flexibility and can be adjusted according to specific application requirements.

[0051] In practice, to achieve optimal contact, it is necessary to precisely control the radius of curvature and position of the arc segment. This typically involves precision machining techniques and rigorous quality control processes.

[0052] By adjusting the specific parameters of the arc segment, the contact area between the base plate and the heat sink can be optimized, thereby affecting the thermal resistance. An ideal contact state not only facilitates efficient heat transfer but also prevents material fatigue or damage caused by localized overheating.

[0053] The short-side cross-sectional profile designed with a circular arc curve can significantly improve the thermal performance of the power module, especially in high power density applications.

[0054] Compared to traditional flat designs or other complex shapes, circular curves simplify the manufacturing process, reduce costs, and improve production efficiency.

[0055] Furthermore, this design approach can significantly improve the uniformity of heat distribution within the module without requiring additional cost investment, thereby enhancing the reliability and lifespan of the entire system.

[0056] In summary, by employing a circular arc curve design for the short-side cross-sectional profile of the power module base plate, this invention provides a simple and effective solution to overcome problems such as high contact thermal resistance and poor thermomechanical reliability in existing technologies. This method not only improves heat transfer efficiency but also enhances mechanical stability and system integration, making it suitable for various high-performance power conversion systems.

[0057] S130. Attach the designed power module to the heat sink of the power conversion system.

[0058] Please see Figure 4 The power module base plate is also equipped with fasteners; the fasteners are tightened symmetrically at four points. These fasteners include locking screws.

[0059] The power module base plate is provided with a locking hole, the diameter of which is 5mm to 9mm.

[0060] The fastener has a diameter of 4 mm to 8 mm and a torque of 2.0 N·m to 4.5 N·m.

[0061] The heat sink uses a thermal interface material with a thickness of 100μm to 200μm and a thermal conductivity of not less than 2.0W / m·K.

[0062] In this embodiment, the optimized power module base plate is fastened to the heat sink of the power conversion system using specific fasteners and parameter configurations to ensure optimal thermal conductivity and mechanical stability.

[0063] To ensure a uniform pressure distribution between the power module base plate and the heat sink, a four-point symmetrical tightening method is used for fixation. This layout helps avoid the formation of interface cavities due to excessive or insufficient local pressure, thereby reducing contact thermal resistance.

[0064] The mounting holes on the power module baseplate are set to a diameter of 5mm to 9mm. Appropriate hole dimensions not only provide sufficient installation space but also ensure that the screws do not damage the baseplate during tightening.

[0065] The diameter of the fastening screws ranges from 4mm to 8mm, and the torque is controlled between 2.0N·m and 4.5N·m. Precise screw diameter and torque settings are crucial for achieving ideal contact surface pressure, which directly affects the heat transfer efficiency between the base plate and the heat sink.

[0066] The thickness of the thermal interface material (TIM) used should be maintained between 100 μm and 200 μm, and its thermal conductivity should not be less than 2.0 W / m·K. High thermal conductivity TIM can effectively fill the tiny gaps between the base plate and the heat sink, reduce contact thermal resistance, and improve heat dissipation.

[0067] By following the steps above, the power module base plate can be securely attached to the heat sink, and the thermal management and mechanical stability of the entire system can be significantly improved, meeting the requirements of high-performance power conversion systems.

[0068] In power conversion systems, thermal management is one of the key factors affecting module performance and reliability. This embodiment significantly reduces contact thermal resistance by optimizing the curvature design of the power semiconductor module baseplate and its bonding method with the heat sink, thereby improving the overall system's heat dissipation efficiency and operational stability.

[0069] Contact thermal resistance accounts for more than 50% of the total thermal resistance. This means that even if other components such as junction-shell thermal resistance (Rth, jc) or system thermal resistance (Rth, hc) are effectively controlled, poor heat conduction between the contact surfaces will still result in heat not being effectively dissipated, thus affecting the module's operating efficiency and lifespan.

[0070] By designing the long side cross-sectional profile of the module base plate as a bimodal Gaussian distribution curve and the short side cross-sectional profile as a circular arc curve (including straight lines), the base plate can fit more tightly against the heat sink surface during installation. This curved surface design helps reduce potential gaps between the base plate and the heat sink, forming a more uniform contact surface, thereby achieving more efficient heat transfer.

[0071] Compared to other technical means that may increase costs (such as using materials with higher thermal conductivity or reducing the package thickness), the present invention can reduce contact thermal resistance simply by optimizing the geometry of the existing structure, without the need for additional investment in expensive materials or complex processes.

[0072] By using a four-point symmetrical tightening method to secure the module base plate, it is ensured that the pressure applied across the entire contact surface is evenly distributed, preventing localized overpressure or underpressure. This not only further reduces the formation of interface cavities but also improves the overall mechanical stability and reliability.

[0073] The specified locking hole diameter, screw diameter, and torque range ensure that the tightness of each connection point is consistent and appropriate, preventing deformation of the base plate due to excessive tightness or unnecessary gaps due to excessive looseness.

[0074] In summary, the method of this embodiment effectively solves the high contact thermal resistance problem existing in traditional power modules through an innovative base plate curvature design combined with an optimized locking method. It not only promotes the uniform distribution of heat within the module but also achieves the goal of improving system thermal performance without incurring additional costs. Therefore, compared to existing solutions, the method of this embodiment provides a more economical, efficient, and easy-to-implement optimization scheme, which is of great significance for improving the overall performance of power conversion systems.

[0075] The aforementioned curved surface design method for a power module base plate, by designing the long side cross-sectional profile as a bimodal Gaussian distribution curve and the short side cross-sectional profile as a circular arc curve, makes the contact between the base plate and the heat sink tighter and smoother, effectively reducing the existence of interface cavities and thus improving heat conduction efficiency. Furthermore, combined with optimized locking techniques such as the four-point symmetrical tightening method, it ensures uniform pressure distribution during installation, enhancing mechanical stability and avoiding deformation or damage caused by localized stress concentration. This method solves the problems of high contact thermal resistance and poor thermomechanical reliability commonly found in existing technologies, providing a solution that significantly improves heat dissipation performance and reliability without additional cost.

[0076] In the several embodiments provided by this invention, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For example, the division of each unit is merely a logical functional division, and there may be other division methods in actual implementation. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed.

[0077] The steps in the method of this invention can be adjusted, merged, or reduced in order according to actual needs. The units in the device of this invention can be merged, divided, or reduced according to actual needs. Furthermore, the functional units in the various embodiments of this invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0078] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, a terminal, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention.

[0079] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for designing the curved surface of a power module base plate, characterized in that, include: The long-side cross-sectional profile of the power module base plate is designed with a bimodal Gaussian curvature. The short-side cross-sectional profile of the power module base plate adopts a circular arc curve design; The designed power module is then attached to the heat sink of the power conversion system. The height difference between the center symmetry point and the edge point of the short side cross-sectional profile of the power module base plate is defined as the lateral arc height, and the lateral arc height is not greater than 75μm; For the long side cross-sectional profile of the power module base plate, on the line segment connecting the center point and the edge point of the long side cross-section, at the peak point of the curvature of the long side cross-sectional profile curve of the power module base plate, a vertical line segment is connected to the curve. The distance between the vertical line segment and the curve at the peak point of curvature is defined as the characteristic arc height, and the characteristic arc height is not greater than 85μm. The curvature distribution function corresponding to the long side cross-sectional profile of the power module base plate is: (x)=κmax[exp(-β(xP(d))²)+exp(-β(x+P(d))²)], where κmax is the maximum curvature, x is the horizontal coordinate, β is the curvature concentration, and there are no curvature abrupt inflection points on the curve that affect the curvature concentration; P(d) is the peak curvature position. (x) is the curvature distribution function.

2. The curved surface design method for a power module base plate according to claim 1, characterized in that, The height difference between the center symmetry point and the edge point of the long side cross-sectional profile of the power module base plate is defined as the longitudinal arc height, which is not greater than 550μm.

3. The curved surface design method for a power module base plate according to claim 1, characterized in that, The distance from the vertical line segment to the central symmetrical point is defined as the peak curvature position, which is no greater than 30mm.

4. The curved surface design method for a power module base plate according to claim 1, characterized in that, Fasteners are also installed on the base plate of the power module; the fasteners are tightened symmetrically at four points.

5. The curved surface design method for a power module base plate according to claim 1, characterized in that, The power module base plate is provided with a locking hole, the diameter of which is 5mm to 9mm.

6. The curved surface design method for a power module base plate according to claim 5, characterized in that, The fasteners have a diameter of 4 mm to 8 mm and a torque of 2.0 N·m to 4.5 N·m.

7. The curved surface design method for a power module base plate according to claim 1, characterized in that, The heat sink uses a thermal interface material with a thickness of 100μm to 200μm and a thermal conductivity of not less than 2.0W / m·K.

Images