Method and device for measuring junction-to-case thermal resistance of double-sided heat dissipation module

Abstract

The invention belongs to the field of thermal resistance measurement of power devices, and particularly discloses a junction-to-case thermal resistance measurement method and device for a double-sided heat dissipation module. On the premise that the double-sided heat dissipation module is always in double-sided cooling, the double-sided junction-to-case thermal resistance of the to-be-tested device is determined by using the transient double-interface method under the top surface separation condition, and then the double-sided junction-to-case thermal resistance of the to-be-tested device is determined by using the transient double-interface method under the bottom surface separation condition. And according to the double-sided junction-to-case thermal resistances of the device to be tested obtained under the two separation conditions, the top surface junction-to-case thermal resistance and the bottom surface junction-to-case thermal resistance of the device to be tested are obtained through top surface and bottom surface heat flow proportion decoupling calculation. According to the invention, through decoupling calculation of the heat flow proportion of the top surface and the bottom surface, the influence of the asymmetric structure of the top surface and the bottom surface is eliminated, the measurement precision of the junction-to-case thermal resistance is high, and the problem that the traditional TDIM cannot directly measure the single-sided junction-to-case thermal resistance of the crimped IGBT under the condition of double-sided cooling is solved.

Description

Technical Field

[0001] The present application relates to the field of thermal resistance measurement of power devices, and more specifically, to a method and device for measuring the junction-to-case thermal resistance of a double-sided heat dissipation module. Background Art

[0002] Offshore wind power systems are a renewable energy solution that harnesses ocean wind energy for power generation. The offshore wind power flexible DC converter is a key component of this system, converting the AC power generated by offshore wind turbines into DC power for efficient transmission to the onshore power grid via submarine cables. The offshore converter station, where the flexible DC converter is installed, is typically located at the center of an offshore wind farm or on an offshore platform close to land, centrally processing and converting electrical energy. Pressed-type insulated gate bipolar transistors (IGBTs) are high-power-density power semiconductor devices widely used in offshore wind power flexible DC converters. Pressed-type IGBTs typically consist of a mold, a plastic frame, silver gaskets, molybdenum sheets, and the IGBT chip. The IGBT chip is the core component of the module, responsible for current switching. The plastic frame secures the IGBT chip. The silver gaskets and molybdenum sheets buffer external pressure and internal thermal stress. The mold serves as the module's outer shell, protecting internal components, providing mechanical support, and electrical insulation to prevent external interference and damage to the module. In the compact space of offshore converter stations, the double-sided cooling feature of press-fit IGBTs greatly improves their power density and heat dissipation performance.

[0003] Thermal resistance is an important parameter for evaluating the heat dissipation performance of power devices. As a type of thermal resistance, the junction-to-case thermal resistance The thermal resistance (RT) is the ratio of the temperature difference between the chip's junction and case temperatures to the heat flux through this path. It measures the ease with which heat is transferred from the chip's interior to the package's outer casing. Compared to power devices with traditional single-sided cooling packaging structures, the double-sided cooling feature of press-fit IGBTs enables lower junction-to-case thermal resistance. Generally speaking, traditional thermal resistance measurement methods for power devices are divided into two main categories: the thermocouple method and the transient dual-interface method (TDIM). Most double-sided thermal resistance test methods utilize the thermocouple method. In single-sided thermal resistance testing, the surface of the power module's outer casing exhibits a certain temperature distribution, resulting in a certain degree of error in the case temperature measurement results and poor repeatability. These issues are particularly prominent in double-sided thermal resistance measurements.

[0004] The TDIM method separates the two measured thermal impedance curves by changing the contact interface material between the module housing and the heat sink. Get the junction-to-case thermal resistance The traditional TDIM has only been studied for the thermal resistance measurement of power devices with a single-channel heat flow path. Usually by separating the two The wet curve is usually obtained by applying a thermal interface material with low thermal resistance and high thermal conductivity (such as thermal grease) between the press-fit IGBT module and the heat sink. The dry curve is usually obtained by applying a thermal interface material with high thermal resistance and low thermal conductivity, or by eliminating any thermal interface material (such as an air layer).

[0005] The traditional TDIM method is only applicable to the thermal resistance measurement of power devices with a single heat source, a single direction, and one-dimensional heat conduction. When a single heat source transfers heat through a double-sided heat dissipation path, there is a heat flow distribution between the two paths, and the size of the heat flow distribution is related to the thermal resistance ratio of the two heat dissipation paths. As a typical double-sided heat dissipation power device, the press-fit insulated gate bipolar transistor has two contact interfaces between the housing and the heat sink, namely the top and bottom surfaces. Under double-sided cooling, there is a real-time heat flow distribution problem in the heat dissipation channels on both sides. Due to the asymmetric heat dissipation structure of the upper and lower sides of the press-fit IGBT, such as Figure 1 As shown, the heat flow of the chip will not reach the top and bottom at the same time. The separation point rule of the traditional TDIM method and the double-sided separation obtained by separation The physical meaning of is not clear, and the result is not the true double-sided junction-to-case thermal resistance of the press-bonded IGBT module. Therefore, traditional TDIM cannot directly measure the single-sided junction-to-case thermal resistance of the press-bonded IGBT under double-sided cooling conditions. Summary of the Invention

[0006] In response to the defects of the existing technology, the purpose of this application is to provide a method and device for measuring the junction-to-case thermal resistance of a double-sided heat dissipation module, aiming to solve the problem that traditional TDIM cannot directly measure the single-sided junction-to-case thermal resistance of a press-connected IGBT under double-sided cooling conditions.

[0007] In a first aspect, the present application provides a method for measuring the junction-to-case thermal resistance of a double-sided heat dissipation module, wherein the housing and the radiator of the double-sided heat dissipation module have two contact interfaces and are always cooled on both sides during the entire measurement process. The measurement method comprises: Under the condition of top surface separation, the transient double-interface method is used to determine the double-sided junction-to-case thermal resistance of the device under test. The top surface separation condition is to keep the bottom surface contact interface of the device under test unchanged and change the thermal conductivity of the contact interface between the top surface and the heat sink; Under the condition of bottom surface separation, the transient double-interface method is used to determine the double-sided junction-to-case thermal resistance of the device under test. The bottom surface separation condition is to keep the top surface contact interface of the device under test unchanged and change the thermal conductivity of the contact interface between the bottom surface and the heat sink; According to the double-sided junction-to-case thermal resistance of the device under test obtained under the two separation conditions, the top surface junction-to-case thermal resistance and the bottom surface junction-to-case thermal resistance of the device under test are obtained by decoupling the heat flux ratio between the top surface and the bottom surface.

[0008] Preferably, the top surface junction-to-case thermal resistance and the bottom surface junction-to-case thermal resistance of the device under test are obtained by decoupling the top surface and bottom surface heat flux ratios, as follows:

[0009] in, and are the top junction-to-case thermal resistance and the bottom junction-to-case thermal resistance, is the double-sided junction-to-case thermal resistance, is the power loss of the device under test, and are the power losses through the top and bottom surfaces, respectively. Indicates the separation time, Indicates that the top surface is separated at this time. This indicates that the bottom surface is separated at this time.

[0010] Preferably, the thermal conductivity of the contact interface is changed by: not applying / applying a thermal interface material at the contact interface, applying two different thermal interface materials at the contact interface, or adding a graphite electrode sheet at the contact interface.

[0011] Preferably, when the wet curve is obtained, the changed thermal conductivity at the contact interface is greater than when the dry curve is obtained.

[0012] Preferably, under the condition of top surface separation, the double-sided junction-to-case thermal resistance of the device under test is determined by using a transient double-interface method, specifically: (1) Perform junction temperature correction on the original device under test to obtain a linear curve of the on-state voltage drop of the device under test with respect to the junction temperature; (2) Obtain the on-state voltage drop change curve of the device under test during the transient process of junction temperature reduction, and reversely calculate the junction temperature correction linear curve to obtain the junction temperature reduction curve; (3) Using the transient double interface method, the junction temperature drop curve and thermal resistance calculation formula are used to obtain the dry curve of the device under test; (4) After changing the thermal conductivity of the interface between the top surface of the device under test and the heat sink, re-calibrate the junction temperature to obtain a linear curve of the on-state voltage drop of the device under test with respect to the junction temperature; (5) Obtain the on-state voltage drop change curve of the device under test during the transient process of junction temperature reduction, and reversely calculate the junction temperature correction linear curve to obtain the junction temperature reduction curve; (6) Using the transient double interface method, the junction temperature drop curve and thermal resistance calculation formula are used to obtain the wet curve of the device under test; (7) Separate the two thermal impedance curves at the point where the dry curve and the wet curve of the device under test first differ, and obtain the double-sided junction-to-case thermal resistance of the device under test.

[0013] In a second aspect, the present application provides a device for measuring the junction-to-case thermal resistance of a double-sided heat dissipation module, wherein the housing and the radiator of the double-sided heat dissipation module have two contact interfaces, and the measuring device includes: a radiator, a heating current source, a diode, an IGBT switch tube, a measuring current source, a voltage acquisition device, an IGBT driver and processing unit, wherein; Radiator, used to cool the outer shell of the collector side and emitter side of the device under test; One end of the heating current source is connected to the collector of the IGBT switch tube, and the other end is connected to the device under test. The emitter of the IGBT switch tube is connected to the anode of the diode, the gate and emitter are connected to the IGBT driver, and the cathode of the diode is connected to the device under test, thus forming a heating circuit; The measuring current source is connected in parallel with the device under test to form a measuring loop; A voltage acquisition device is used to measure the conduction and crimping of the device under test and send it to the processing unit; The processing unit is used to control the on and off of the IGBT switch tube by controlling the IGBT drive, and calculate the junction-to-case thermal resistance of the device under test based on the measured conduction pressure of the device under test.

[0014] Preferably, the heating circuit and the measuring circuit do not operate simultaneously.

[0015] Preferably, the sampling speed of the voltage acquisition device is not less than 250 kS / s.

[0016] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the existing technologies: This application proposes a method for measuring the junction-to-case thermal resistance of a double-sided heat dissipation module. Under the premise that the double-sided heat dissipation module is always under double-sided cooling, the double-sided junction-to-case thermal resistance of the device to be tested is first determined using the transient double-interface method under the condition of top surface separation, and then under the condition of bottom surface separation, the double-sided junction-to-case thermal resistance of the device to be tested is determined using the transient double-interface method. Then, based on the double-sided junction-to-case thermal resistance of the device to be tested obtained under the two separation conditions, the top surface and bottom surface heat flux ratio decoupling calculations are performed to obtain the top surface and bottom surface junction-to-case thermal resistances of the device to be tested. By decoupling the top and bottom surface heat flux ratio calculations, the influence of the asymmetric structure of the top and bottom surfaces is eliminated, and the junction-to-case thermal resistance measurement accuracy is high. This solves the problem that traditional TDIM cannot directly measure the single-sided junction-to-case thermal resistance of a press-fit IGBT under double-sided cooling conditions, provides a theoretical basis for the junction-to-case thermal resistance measurement of double-sided heat dissipation modules, and has certain reference value and application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the structure of a press-fit IGBT module provided by the prior art.

[0018] Figure 2This is a schematic diagram of a single heat source dual-channel heat transfer model provided in an embodiment of the present application.

[0019] Figure 3 Schematic diagram of the thermal network model of the crimped IGBT under two conditions provided in the embodiments of the present application; (a) is single-sided removal, and (b) is single-sided insulation.

[0020] Figure 4 The embodiment of the present application provides a single-sided demolition and single-sided insulation Curve (a) is Curve difference comparison, (b) is measured by TDIM method contrast.

[0021] Figure 5 The transient heat flow distribution and the heat flux distribution of the press-fit IGBT module provided by the embodiment of the present application are as follows: The physical meaning of the curve; (a) is the heat flow reaching the top shell, (b) is The curves separate at the top surface, (c) is the heat flow reaching the bottom shell, and (d) is The curves separate at the top surface.

[0022] Figure 6 This is a schematic diagram of the finite element simulation model of the crimped IGBT provided in an embodiment of the present application.

[0023] Figure 7 The TDIM method is used to measure the single-sided cooling condition provided in the embodiment of the present application. and (a) is , (b) is .

[0024] Figure 8 This is a schematic diagram of the internal temperature distribution of the entire thermal transient process of the press-fit IGBT under different heat dissipation conditions provided in an embodiment of the present application.

[0025] Figure 9 It is a single surface of different top and bottom separation materials provided in the embodiment of the present application Results of curve parallel connection; (a) is the top surface (dry curve) - the bottom surface (dry curve), (b) is the top surface (wet curve) - the bottom surface (wet curve), (c) is the top surface (wet curve) - the bottom surface (dry curve), and (d) is the top surface (dry curve) - the bottom surface (wet curve).

[0026] Figure 10 The six groups of TDIM provided in the embodiment of this application are Curve separation results; (a) is group 1, (b) is group 2, (c) is group 3, (d) is group 4, (e) is group 5, and (f) is group 6.

[0027] Figure 11This is a circuit diagram of a junction-to-case thermal resistance measurement device for a double-sided heat dissipation module provided in an embodiment of the present application.

[0028] Figure 12 This is a timing diagram of the load current and the measurement current provided in an embodiment of the present application.

[0029] Figure 13 This is a schematic diagram of the various parts of the press-fit IGBT thermal resistance test experimental platform provided in an embodiment of the present application.

[0030] Figure 14 These are the experimental results of TDIM under double-sided cooling conditions provided in the embodiments of the present application; (a) is top surface separation, and (b) is bottom surface separation.

[0031] Figure 15 This is a flow chart of a method for measuring the junction-to-case thermal resistance of a double-sided heat dissipation module provided in an embodiment of the present application. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0033] The term "and / or" in this application describes an association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, or B exists alone. The symbol " / " in this application indicates that the associated objects are in an "or" relationship, for example, A / B means A or B.

[0034] In this application, the terms "first" and "second" are used to distinguish different objects, rather than to describe a specific order of objects. For example, the terms "first response message" and "second response message" are used to distinguish different response messages, rather than to describe a specific order of response messages.

[0035] The term "electrical connection" in this application can be a direct circuit connection or a signal transmission through a communication protocol.

[0036] In the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0037] In the description of the embodiments of the present application, unless otherwise specified, "multiple" means two or more, for example, multiple processing units means two or more processing units, etc.; multiple elements means two or more elements, etc.

[0038] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0039] The "double-sided heat dissipation module" referred to in this application refers to a device with a housing and a heat sink having two contact interfaces, including but not limited to: a press-fit IGBT. The following description uses a press-fit IGBT as an example.

[0040] like Figure 2 As shown, since both heat dissipation channels of the press-fit IGBT module have a certain thermal resistance ( ) and heat capacity ( ), , ,in, is the thickness of the material layer, is the effective heat transfer area perpendicular to the direction of heat conduction, is the thermal conductivity of the material, is the volume of the material layer, The junction temperature of the double-sided heat dissipation module rises slower than that of the single-sided heat dissipation module. The logarithmic coordinate of time, the vertical coordinate Indicates the chip junction temperature. The power loss of the chip is usually the heat generated by the press-fit IGBT under normal conduction conditions, which is calculated from the on-state pressure and conduction current of the press-fit IGBT.

[0041] To study the double-sided compression bonding of IGBT The measurement method of this application is to measure the top surface shell thermal resistance under single-sided cooling conditions ( ) and bottom-to-case thermal resistance ( ) for analysis. Transient thermal analysis is a method for studying the thermal behavior of semiconductor devices under dynamic operating conditions, such as switching operations. The transient region refers to the brief interval when a device transitions from its initial state (such as static operating conditions) to a new steady-state condition (such as after a switching operation). During this region, the device's temperature and heat flow change rapidly. Thermal impedance curves, derived through transient thermal analysis, describe the temporal changes in device temperature within the transient region, reflecting the device's thermal impedance characteristics under dynamic operating conditions.

[0042] In the thermal simulation analysis, by completely removing the material on the other side of the press-fit IGBT module, the and However, in experimental tests, completely removing the structural material on one side of the crimped IGBT module will destroy the original electrical connection, making it impossible to form a current path. Generally, insulating material is placed at the contact surface between the module housing and the heat sink to simulate single-sided cooling (single-sided insulation). The thermal network models for the two cases are as follows: Figure 3 shown.

[0043] like Figure 3 As shown in (a), in the case of single-sided removal, there is only one heat dissipation path in the thermal network model.

[0044] like Figure 3 As shown in (b), in the case of single-sided insulation, the heat capacity of a part of the material layer still exists in the insulation path in the thermal network model, but heat cannot be transferred and only heat is stored.

[0045] A comparison revealed that the heat transfer process in the transient thermal analysis of press-fit IGBTs differed significantly between the single-sided removal and single-sided insulation cases. While the single-sided removal case allowed for a heat dissipation path, the thermal resistance of the material layer on the insulation side prevented heat transfer. However, the thermal capacitance still allowed for heat storage during the initial stages of transient heat conduction.

[0046] Taking the bottom edge as an example, the thermal impedance of the transient region in two cases is The curves are also different, but the thermal resistance from the chip to the water inlet of the water cooling radiator in the steady state ( ) are the same as Figure 4 As shown in (a). Although the heat transfer path on the bottom side of the chip is blocked by the single-sided insulation, the heat capacitance on the bottom side increases in the initial stage of transient heat transfer (the area where the thermal impedance curve rises). A certain amount of IGBT chip heat flow is still stored. Under the condition of single-sided insulation, the junction temperature of the press-fit IGBT module ( ) rises slower than under the condition of single-sided removal, resulting in thermal impedance The value is small. Separation in TDIM under single-sided insulation The top surface junction-to-case thermal resistance obtained from the curve is smaller than the actual value, such as Figure 4 Therefore, the single-sided insulation condition cannot accurately measure the top surface junction-to-case thermal resistance. and bottom-to-case thermal resistance .

[0047] Due to the top surface junction to case thermal resistance of the press-fit IGBT Less than the bottom-to-case thermal resistance , the heat first reaches the top shell surface, and the heat from the bottom path is only transferred to the middle of the emitter copper base. According to the second law of thermodynamics, the temperature of the area not reached by heat remains unchanged, which is equal to the water inlet temperature of the water cooling radiator ( ),like Figure 5As shown in (a). When only the interface material between the top surface shell and the heat sink is changed, the separation point of TDIM appears at the top surface shell, and the separation time is ,like Figure 5 As shown in (b). When the heat on the bottom path is transferred to the bottom shell, the heat on the top path has been transferred to the middle of the water cooling plate, as shown in Figure 5 As shown in (c). When only the interface material between the bottom shell and the heat sink is changed, the separation point of TDIM appears at the bottom shell, and the separation time is ,like Figure 5 As shown in (d). Less than ,so Less than When the interface materials between the top and bottom shell and heat sink are changed simultaneously, the separation point of TDIM will be and The smaller side between the two sides is given priority, that is, the top side. Under the condition of top or bottom surface separation, the TDIM method can measure the two sides. Then, according to the parallel connection rule of the class circuit, the heat flow ratio of the top and bottom surfaces can be decoupled and calculated to obtain the single-sided junction-to-case thermal resistance of the press-fit IGBT. and .

[0048]

[0049] in, and are the power losses through the top and bottom surfaces, respectively. This is the power loss of the pressed IGBT chip.

[0050] In order to further study the The physical meaning and separation law of the curves were studied, and a transient thermal simulation model of the press-fit IGBT based on the finite element method was established. Figure 6 shown.

[0051] First, when one side is removed, the TDIM method is used to measure the single side and After the bottom structure is completely removed, the measured 0.263K / W, is 0.28s, such as Figure 7 As shown in (a). After the top surface structure is completely removed, the measured is 0.579K / W, is 1.2s, such as Figure 7 As shown in (b).

[0052] Figure 8For the entire thermal transient process, the IGBT can be pressed with the top surface heat dissipation, bottom surface heat dissipation and double-sided heat dissipation. The simulation results show that during the thermal transient process of the IGBT under pressure, the heat flow first reaches the top shell and then the bottom shell.

[0053] The heat transfer direction of the press-fit IGBT is from the chip to the external environment. During the thermal transient process, the area on both sides where no heat is transferred is the isothermal surface, and its value is .by As the reference temperature, refer to the parallel circuit formula, the single-sided heat dissipation of the two branches can be reduced to The curves are directly connected in parallel to obtain the double-sided cooling condition. Curve. Change the top and bottom interface materials The curves are connected in parallel, such as Figure 9 As shown in (a), the top surface (dry curve) - bottom surface (dry curve) The curves are connected in parallel, such as Figure 9 As shown in (b), the top surface (wet curve) - bottom surface (wet curve) The curves are connected in parallel, such as Figure 9 As shown in (c), the top surface (wet curve) - bottom surface (dry curve) The curves are connected in parallel, such as Figure 9 As shown in (d), the top surface (dry curve) - bottom surface (wet curve) The curves are connected in parallel, Figure 9 It can be seen that the error between the parallel thermal resistance and the double-sided heat dissipation thermal resistance simulation result is within 0.009K / W.

[0054] In order to verify the position rule of TDIM separation point under double-sided cooling conditions: if only one side of the shell and the heat sink interface uses different interface materials, separation will be carried out directly on that side; if different interface materials are used on both sides, separation will be prioritized on the side with lower thermal resistance. A total of six groups of TDIM transient thermal simulation tests were conducted. The measurement conditions of the six groups of TDIM are as follows: The separation point position and separation time of the curve are shown in Table 1.

[0055] Table 1 Six groups of differences Curve separation law

[0056] The results are as follows Figure 10 As shown, the results show that the first and third groups only changed the top surface interface material, and the separation point was at the top surface shell. The second and fourth groups only changed the bottom interface material, and the separation point was at the bottom shell. At the same time, the top and bottom interface materials of Groups 5 and 6 were changed at the same time, and the separation point appeared on the top shell, and the separation time was 0.28s. Even if the thermal transient process of the press-fit IGBT reaches 1.2s, there will be differences in the bottom shell interface, but This change cannot be seen on the separation curve. Curve measurement double side , using the power heat flow ratio to infer the single-sided and They are 0.261K / W and 0.563K / W respectively, as shown in Table 2.

[0057] Table 2 Double-sided , single-sided and Simulation results

[0058] Through the study of the double-sided heat dissipation mechanism, the TDIM thermal impedance curve under double-sided cooling conditions is revealed. On this basis, the present application proposes a device for measuring the junction-to-shell thermal resistance of a double-sided heat dissipation module, wherein the housing and the heat sink of the double-sided heat dissipation module have two contact interfaces, such as Figure 11 As shown, the measuring device includes: a heat sink, a heating current source, a diode, an IGBT switch tube, a measuring current source, a voltage acquisition device, an IGBT drive and processing unit, wherein; Radiator, used to cool the outer shell of the collector side and emitter side of the device under test; One end of the heating current source is connected to the collector of the IGBT switch tube, and the other end is connected to the device under test. The emitter of the IGBT switch tube is connected to the anode of the diode, the gate and emitter are connected to the IGBT driver, and the cathode of the diode is connected to the device under test, thus forming a heating circuit; The measuring current source is connected in parallel with the device under test to form a measuring loop; A voltage acquisition device is used to measure the conduction and crimping of the device under test and send it to the processing unit; The processing unit is used to control the on and off of the IGBT switch tube by controlling the IGBT drive, and calculate the junction-to-case thermal resistance of the device under test based on the measured conduction pressure of the device under test.

[0059] Preferably, the heating circuit and the measuring circuit do not operate simultaneously.

[0060] Preferably, the sampling speed of the voltage acquisition device is not less than 250 kS / s.

[0061] According to the JESD51-14 standard, the cooling curve of the press-fit IGBT is generally measured. , where the heating current ( ) and the measured current ( ) Timing as Figure 12 As shown, is the initial heating moment, To press the IGBT to reach thermal steady state, This is the initial moment of cooling of the crimped IGBT. This is the moment when the press-fit IGBT cooling reaches a steady state. During this period, the press-fit IGBT is in the transient process of junction temperature rising; During this period, the press-fit IGBT is in the steady-state process of increasing junction temperature; During this period, the IGBT is in a transient process of decreasing junction temperature. Flowing into the heating circuit, affecting the thermal resistance measurement results.

[0062] To verify the separation law of TDIM under double-sided cooling conditions, this example built a press-fit IGBT junction-to-case thermal resistance test platform. The device under test (DUT) uses an IXYS 4500V / 50A IGBT chip. Each material component in the press-fit IGBT module is custom-processed and packaged. The press-fit IGBT thermal resistance test platform mainly consists of the device under test, gate driver, DSP, Collection devices, such as Figure 13 As shown, the heating current source is connected to the IGBT switch tube, which is connected to the diode, which is connected to the device under test, thus forming a heating circuit. The measurement power supply and the device under test are connected in parallel to form a measurement circuit. The voltage acquisition device is used to measure the IGBT conduction voltage. The IGBT driver and DSP are used to control the IGBT switching. The water cooling box is connected to the water cooling radiator to cool the IGBT.

[0063] Two sets of TDIM experimental results were obtained by using different interface materials on the top and bottom surfaces, as shown in Figure 2. Figure 14 The results show that Less than , 0.3 s and 1.1 s respectively. The experimental results verify that during the transient thermal process of the press-fit IGBT module, the heat flow first flows to the top shell and then to the bottom shell. Therefore, The curve separates first at the top shell and then at the bottom shell.

[0064] like Figure 15 As shown, the present application proposes a method for measuring the junction-to-case thermal resistance of a double-sided heat dissipation module. The housing and the radiator of the double-sided heat dissipation module have two contact interfaces, and the module is always cooled on both sides during the entire measurement process. The measurement method includes: Under the condition of top surface separation, the transient double-interface method is used to determine the double-sided junction-to-case thermal resistance of the device under test. The top surface separation condition is to keep the bottom surface contact interface of the device under test unchanged and change the thermal conductivity of the contact interface between the top surface and the heat sink; Under the condition of bottom surface separation, the transient double-interface method is used to determine the double-sided junction-to-case thermal resistance of the device under test. The bottom surface separation condition is to keep the top surface contact interface of the device under test unchanged and change the thermal conductivity of the contact interface between the bottom surface and the heat sink; According to the double-sided junction-to-case thermal resistance of the device under test obtained under the two separation conditions, the top surface junction-to-case thermal resistance and the bottom surface junction-to-case thermal resistance of the device under test are obtained by decoupling the heat flux ratio between the top surface and the bottom surface.

[0065] The following uses the top surface separation condition as an example to explain how to determine the double-sided junction-to-case thermal resistance of the device under test using the transient double-interface method. Specifically: Step 1: First, perform the junction temperature correction of the press-fit IGBT to obtain the on-state voltage drop of the press-fit IGBT and junction temperature relationship.

[0066] Specifically, two heated aluminum plates are placed on both sides of the IGBT module and heated continuously. When the pressed IGBT reaches thermal steady state, the temperature of the aluminum plate is approximately equal to the chip junction temperature. The temperature of the aluminum plate and the temperature of the pressed IGBT are measured at different temperatures. , the junction temperature correction curve with good linear relationship is obtained by fitting .

[0067] Step 2: Measure the junction temperature drop curve of the press-fit IGBT under cooling, and obtain the thermal impedance curve of the press-fit IGBT using the transient double interface method. .

[0068] Specifically, first, a constant heating current is applied to the device under test. and heating current The conduction time is 5 minutes. When the IGBT reaches the thermal steady state, the heating current is turned off. , while measuring the crimped IGBT Change curve until the press-fit IGBT is completely cooled, and the junction temperature correction curve is used The junction temperature drop curve is obtained by reverse deduction. The thermal impedance curve of the press-fit IGBT is obtained by using the transient double interface method, the junction temperature drop curve and the thermal resistance calculation formula. (Measure the dry curve, do not apply silicone grease between the top surface and the water cooling radiator, and the bottom surface remains unchanged).

[0069] Step 3: Change the material of the top or bottom shell contact surface of the crimped IGBT and repeat steps 1 and 2 to obtain the second crimped IGBT thermal impedance curve. (Measure the wet curve and apply silicone grease between the top surface and the water cooling radiator).

[0070] Step 4: Separate the two thermal impedance curves at the point where the two curves first differ to obtain the double-sided junction-to-case thermal resistance of the press-bonded IGBT.

[0071] The separation method is in accordance with JESD51-14 standard.

[0072] It should be understood that the above-mentioned device is used to execute the method in the above-mentioned embodiment. The implementation principle and technical effect of the corresponding program module in the device are similar to those described in the above-mentioned method. The working process of the device can refer to the corresponding process in the above-mentioned method and will not be repeated here.

[0073] Based on the methods in the above embodiments, embodiments of the present application provide an electronic device that may include: a processor, a communications interface, a memory, and a communication bus, wherein the processor, the communications interface, and the memory communicate with each other via the communication bus. The processor may invoke logic instructions in the memory to execute the methods in the above embodiments.

[0074] In addition, the logical instructions in the above-mentioned memory can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when sold or used as an independent product. Based on this understanding, the technical solution of the present application, or the part that contributes to the existing technology, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a number of instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application.

[0075] Based on the method in the above embodiment, an embodiment of the present application provides a computer-readable storage medium, which stores a computer program. When the computer program runs on a processor, the processor executes the method in the above embodiment.

[0076] Based on the method in the above embodiment, an embodiment of the present application provides a computer program product. When the computer program product runs on a processor, the processor executes the method in the above embodiment.

[0077] It is understood that the processor in the embodiments of the present application may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA), other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

[0078] The method steps in the embodiments of the present application can be implemented by hardware or by a processor executing software instructions. The software instructions can be composed of corresponding software modules, which can be stored in random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, mobile hard disks, CD-ROMs, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. Of course, the storage medium can also be an integral part of the processor. The processor and storage medium can be located in an ASIC.

[0079] The above embodiments can be implemented in whole or in part using software, hardware, firmware, or any combination thereof. When implemented using software, they can be implemented in whole or in part in the form of a computer program product. The computer program product comprises one or more computer instructions. When loaded and executed on a computer, the computer program instructions fully or partially produce the processes or functions described in the embodiments of this application. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted via the computer-readable storage medium. The computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible by a computer or a data storage device such as a server or data center that integrates one or more available media. The available medium can be magnetic media (e.g., floppy disk, hard disk, tape), optical media (e.g., DVD), or semiconductor media (e.g., solid-state drive (SSD)).

[0080] It will be understood that the various numerical numbers involved in the embodiments of the present application are merely distinctions for the convenience of description and are not intended to limit the scope of the embodiments of the present application.

[0081] It is easy for those skilled in the art to understand that the above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for measuring the junction-to-case thermal resistance of a double-sided heat dissipation module, characterized in that: The housing and the radiator of the double-sided heat dissipation module have two contact interfaces, and the module is always cooled on both sides during the entire measurement process. The measurement method includes: Under the condition of top surface separation, the transient double-interface method is used to determine the double-sided junction-to-case thermal resistance of the device under test. The top surface separation condition is to keep the bottom surface contact interface of the device under test unchanged and change the thermal conductivity of the contact interface between the top surface and the heat sink; Under the condition of bottom surface separation, the transient double-interface method is used to determine the double-sided junction-to-case thermal resistance of the device under test. The bottom surface separation condition is to keep the top surface contact interface of the device under test unchanged and change the thermal conductivity of the contact interface between the bottom surface and the heat sink; According to the double-sided junction-to-case thermal resistance of the device under test obtained under the two separation conditions, the top surface junction-to-case thermal resistance and the bottom surface junction-to-case thermal resistance of the device under test are obtained by decoupling the heat flux ratio between the top surface and the bottom surface.

2. The measuring method according to claim 1, wherein The top surface junction-to-case thermal resistance and the bottom surface junction-to-case thermal resistance of the device under test are obtained by decoupling the top surface and bottom surface heat flux ratios, as follows: in, and are the top junction-to-case thermal resistance and the bottom junction-to-case thermal resistance, is the double-sided junction-to-case thermal resistance, is the power loss of the device under test, and are the power losses through the top and bottom surfaces, respectively. Indicates the separation time, Indicates that the top surface is separated at this time. This indicates that the bottom surface is separated at this time.

3. The measuring method according to claim 1, wherein: The thermal conductivity of the contact interface is changed by: applying / not applying a thermal interface material at the contact interface, applying two different thermal interface materials at the contact interface, or adding a graphite electrode sheet at the contact interface.

4. The measuring method according to claim 3, wherein: The changed thermal conductivity at the contact interface is greater when the wet curve is obtained than when the dry curve is obtained.

5. The measuring method according to claim 1, wherein: Under the condition of top surface separation, the double-sided junction-to-case thermal resistance of the device under test is determined by using the transient double-interface method, specifically: (1) Perform junction temperature correction on the original device under test to obtain a linear curve of the on-state voltage drop of the device under test with respect to the junction temperature; (2) Obtain the on-state voltage drop change curve of the device under test during the transient process of junction temperature reduction, and reversely calculate the junction temperature correction linear curve to obtain the junction temperature reduction curve; (3) Using the transient double-interface method, the junction temperature drop curve and thermal resistance calculation formula are used to obtain the dry curve of the device under test; (4) After changing the thermal conductivity of the interface between the top surface of the device under test and the heat sink, re-calibrate the junction temperature to obtain a linear curve of the on-state voltage drop of the device under test with respect to the junction temperature; (5) Obtain the on-state voltage drop change curve of the device under test during the transient process of junction temperature reduction, and reversely calculate the junction temperature correction linear curve to obtain the junction temperature reduction curve; (6) Using the transient double interface method, the junction temperature drop curve and thermal resistance calculation formula are used to obtain the wet curve of the device under test; (7) Separate the two thermal impedance curves at the point where the dry curve and the wet curve of the device under test first differ, and obtain the double-sided junction-to-case thermal resistance of the device under test.

6. A device for measuring the junction-to-case thermal resistance of a double-sided heat dissipation module, characterized in that: The housing and the radiator of the double-sided heat dissipation module have two contact interfaces, and the measuring device includes: a radiator, a heating current source, a diode, an IGBT switch tube, a measuring current source, a voltage acquisition device, an IGBT drive and processing unit, wherein; Radiator, used to cool the outer shell of the collector side and emitter side of the device under test; One end of the heating current source is connected to the collector of the IGBT switch tube, and the other end is connected to the device under test. The emitter of the IGBT switch tube is connected to the anode of the diode, the gate and emitter are connected to the IGBT driver, and the cathode of the diode is connected to the device under test, thus forming a heating circuit; The measuring current source is connected in parallel with the device under test to form a measuring loop; A voltage acquisition device is used to measure the conduction and crimping of the device under test and send it to the processing unit; The processing unit is used to control the on and off of the IGBT switch tube by controlling the IGBT drive, and calculate the junction-to-case thermal resistance of the device under test based on the measured conduction pressure of the device under test.

7. The measuring device according to claim 6, wherein The heating circuit and the measuring circuit do not operate simultaneously.

8. The measuring device according to claim 6, wherein The sampling speed of the voltage acquisition device is not less than 250 kS / s.

Images