A device and method for testing temperature and stress of an IGBT module generated by power cycle

Abstract

The invention discloses an IGBT module temperature and stress test device and method for generating heat by power circulation. The device comprises a DC stable power supply, a time delay relay, a micro circular high temperature ceramic rapid heating sheet, an IGBT module, an oscilloscope, an infrared camera, a right-angle strain rosette, a dynamic strain gauge and a PC. The method uses a time delay relay to connect a power supply and the micro circular high temperature ceramic rapid heating sheet, and utilizes the time delay circulation function of the time delay relay to provide different voltages to the micro circular high temperature ceramic rapid heating sheet in a cycle, so as to achieve the purpose of generating heat for the IGBT module in a cycle. The temperature of the IGBT module at this time can be accurately measured by the infrared camera, so as to provide a basis for subsequent stress-strain experiments at a certain temperature. The IGBT module is connected to the dynamic strain gauge by a right-angle strain rosette, so as to measure the strain of the measured position in real time, and the strain result is displayed on the PC. The temperature and stress test of the IGBT module under different power load loading conditions can be realized by utilizing the experimental data.

Description

Technical Field

[0001] The invention relates to the technical field of electronic component packaging and testing, in particular to an IGBT module temperature and stress testing device and method that generates heat through power circulation. Background Art

[0002] Insulated Gate Bipolar Transistor (IGBT) is a power semiconductor device with high input impedance, low on-state voltage, high current, good thermal stability, and extremely fast switching speed. It is widely used in high-speed rail control systems, automotive electronic components, wind and solar power generation, and home appliance working modules. During the operation of the IGBT module, the IGBT module will have a working cycle, that is, the process of power-on-operation-power-off. In this process, the temperature change will cause the IGBT module to be subjected to the temperature cycle load. Because the thermal expansion coefficients of the various parts of the IGBT module are different, thermal stress will be generated, resulting in the peeling of the solder layer. The solder layer not only plays a role in connection and support in the module, but also an important heat dissipation channel. Therefore, its reliability plays a key role in the reliability of the entire IGBT module. For the research on the thermal reliability of solder joints, most domestic and foreign scholars conduct thermal analysis of the module from the perspective of thermal design through simulation, analyze the temperature distribution law of the module, or study the temperature distribution or mechanical response of the module from the perspective of power cycle. Whether the simulation of the IGBT module is correct or not still needs to be verified experimentally. Summary of the invention

[0003] The purpose of the present invention is to provide an IGBT module temperature and stress testing device and method generated by power cycle heat. The method experimentally verifies the temperature and stress of the solder layer of the IGBT module based on the power cycle heat generation; the loading conditions of the power cycle are formed by a time delay relay module, and then the temperature and stress test of the solder layer of the IGBT module is realized by an infrared camera and a dynamic strain gauge. The device is simple in design and can realize the loading of different power loads, which greatly facilitates the verification of the correctness of software simulation.

[0004] The technical solution for achieving the purpose of the present invention is:

[0005] A temperature and stress test device for an IGBT module generated by power cycle heat comprises a DC regulated power supply, a time delay relay and a micro circular high temperature ceramic heating plate connected in sequence; the micro circular high temperature ceramic heating plate is placed on the chip of the IGBT module to simulate chip heating; a blind hole is opened on the back of the chip of the IGBT module to expose a solder layer, a right-angle strain gauge is adhered to the solder layer, and the right-angle strain gauge is connected to a dynamic strain gauge to display the strain of the solder layer of the IGBT module due to power cycle heat generation on a PC; an infrared camera is arranged around the IGBT module to record the temperature of the IGBT module test piece at two moments of high and low power; both ends of the micro circular high temperature ceramic heating plate are also connected in parallel with the signal input end of an oscilloscope to detect the voltage on the ceramic heating plate to form a voltage waveform.

[0006] The time delay relay is a cyclic timing relay.

[0007] The right-angle strain gauge adopts a right-angle strain rosette that can withstand a temperature of -40-150°C and has medium temperature resistance, which can ensure that the strain gauge is basically not affected by temperature when the device is working, thereby ensuring the accuracy of the strain test.

[0008] The method for measuring the temperature and stress of an IGBT module using the above-mentioned IGBT module temperature and stress testing device generated by power cycle heat comprises the following steps:

[0009] 1) Based on ANSYS APDL, an IGBT module simulation model is established and a cyclic power load is applied to it to obtain the simulated temperature and simulated stress values ​​of the IGBT module solder layer;

[0010] 2) Obtain the total thermal power applied to n chips on the IGBT module simulation model: The power applied to the chip in the simulation is loaded in the form of density. The total cyclic high and low power applied to the n chips in the IGBT module is obtained by multiplying the power density by the total volume of the chip;

[0011] 3) Obtaining the output voltage value of the DC stabilized power supply: According to P=UI, n chips in the IGBT module correspond to n miniature circular high-temperature ceramic heating plates, and the miniature circular high-temperature ceramic heating plates are connected in series. By adjusting the output voltage of the DC stabilized power supply, the output voltage value of the DC stabilized power supply is obtained when the total thermal power is known;

[0012] 4) Making an IGBT module test sample, and opening a blind hole on the back of the chip of the IGBT module test sample that is large enough to place a right-angle strain gauge, and the solder layer can be seen;

[0013] 5) Paste the right-angle strain gauge on the solder layer, connect the right-angle strain gauge to the dynamic strain gauge through three signal output lines, and place n miniature circular high-temperature ceramic heating plates on the n chips of the IGBT module test sample, and connect the n miniature circular high-temperature ceramic heating plates in series between the delay relay and the DC stable power supply;

[0014] 6) Connect the overall physical circuit: connect the DC stable power supply, the delay relay, and the micro-circular high-temperature ceramic heating plate end to end to form a closed loop. After power is turned on, the micro-circular high-temperature ceramic heating plate heats up and plays a role in heating the chip, realizing the chip power cycle heat generation;

[0015] 7) Connect the two ends of the oscilloscope to the overall physical circuit, first calibrate the oscilloscope, then connect the clip and hook of the oscilloscope signal input end in parallel to the two ends of n miniature circular high-temperature ceramic heating plates connected in series, where the hook is connected to the positive electrode and the clip is connected to the negative electrode, so as to detect the voltage on the n miniature circular high-temperature ceramic heating plates and form a corresponding voltage waveform;

[0016] 8) Obtaining the temperature of the IGBT module test sample: According to the voltage waveform displayed by the oscilloscope in step 7), when the last cycle is reached, the temperature of the IGBT module test sample at high and low power moments is recorded by an infrared camera;

[0017] 9) Obtain the strain value of the solder layer of the IGBT module test sample: According to the right-angle strain gauge connected to the dynamic strain gauge, the strain values ​​of the solder layer measured by the three-axis right-angle strain gauge in the three directions of 0°, 45° and 90° under the plane stress state are displayed on the PC;

[0018] 10) Compare the actually measured temperature with the temperature obtained by simulation in step 1), and calculate the stress value obtained by the actually measured strain value using the strain rosette formula and compare it with the stress value obtained by simulation in step 2).

[0019] In step 3), the output voltage value of the DC stable power supply is obtained by first connecting n miniature circular high-temperature ceramic heating plates in series to the positive and negative ends of the DC stable power supply, and then gradually adjusting the output voltage of the DC stable power supply under known high and low power loading conditions through the formula P=UI. The display button on the DC stable power supply is used to switch the displayed voltage and current values. According to the equal current values ​​in the series circuit, the voltage values ​​on the n identical miniature circular high-temperature ceramic heating plates are equal, and finally the high and low powers that need to be loaded on the ceramic heating plates are adjusted.

[0020] In step 4), the preparation of the IGBT module test sample is specifically carried out according to step 1) to obtain the solder layer of which chip the maximum stress value appears under the condition of applying a cyclic power load, and then drilling a hole on the back of the corresponding chip, using a flat milling head with a diameter slightly larger than the right-angle strain gauge to drill a blind hole of a certain depth on a drilling machine so that the solder layer is just exposed.

[0021] In step 6), the connection of the overall physical circuit is specifically as follows: first, one output end of the DC stable power supply is connected to the driving end of the delay relay to drive the delay relay module, and then the positive poles of the high-power output end and the low-power output end of the DC stable power supply are respectively connected to the two output ports of the output end of the delay relay, and then the input port of the output end of the delay relay is connected in series with n miniature circular high-temperature ceramic heating plates, and then the miniature circular high-temperature ceramic heating plates are connected to the negative poles of the two output ends of the DC stable power supply.

[0022] In step 10), the calculation formula of the stress value is as follows:

[0023]

[0024]

[0025]

[0026] Where σ1 is the maximum principal stress, σ3 is the minimum principal stress, ε1 is the maximum principal strain, and ε3 is the minimum principal strain; ε 0° , ε 45° and ε 90° They are the linear strains in three directions measured by the triaxial right-angle strain gauge under plane stress state; E is the elastic modulus; μ is the Poisson's ratio.

[0027] The present invention provides an IGBT module temperature and stress test device and method for heat generation by power cycle. The method uses a time delay relay to connect the power supply and the micro-circular high-temperature ceramic rapid heating plate. The time delay cycle function of the time delay relay can provide different voltages to the micro-circular high-temperature ceramic rapid heating plate to achieve the purpose of cyclic heat generation for the IGBT module. The temperature of the IGBT module at this time can be accurately measured by an infrared camera, providing a basis for subsequent stress-strain experiments at a certain temperature. The IGBT module and the dynamic strain gauge are connected by a right-angle strain rosette, and the strain of the measured position can be measured in real time. The strain result is displayed on a PC, and the temperature and stress test of the IGBT module can be realized by using the experimental data. The device has the characteristics of simple structure, strong flexibility, and affordable price. It can realize temperature and stress testing under different power load loading conditions, greatly facilitates the verification of the correctness of software simulation, and has certain significance for verifying the reliability of simulation results. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The present invention is a structural block diagram of an IGBT module temperature and stress test device that generates heat through power circulation;

[0029] Figure 2 This is a finite element analysis model diagram of the IGBT module based on power cycle heat generation;

[0030] Figure 3 It is a heat generating power loading curve diagram;

[0031] Figure 4 This is the temperature distribution diagram of the solder layer of the IGBT module;

[0032] Figure 5 This is the stress distribution diagram of the solder layer of the IGBT module;

[0033] Figure 6 This is a real sample picture;

[0034] Figure 7 This is the sample picture after pasting the right-angle strain rosette;

[0035] Figure 8 This is the overall physical picture;

[0036] Fig. 9 It is the overall circuit connection diagram;

[0037] Fig.10 This is the voltage waveform of the oscilloscope output;

[0038] Fig.11 is the temperature diagram of the test sample;

[0039] Fig.12 Strain curve diagram for dynamic strain gauge measurement. DETAILED DESCRIPTION

[0040] The present invention is further described below with reference to the accompanying drawings and embodiments, but the present invention is not limited thereto.

[0041] like Figure 1As shown, a temperature and stress test device for an IGBT module generated by power cycle heat comprises a DC regulated power supply, a time delay relay and a micro circular high temperature ceramic heater connected in sequence; the micro circular high temperature ceramic heater is placed on the chip of the IGBT module to simulate chip heating; a blind hole is opened on the back of the chip of the IGBT module to expose the solder layer, a right-angle strain gauge is adhered to the solder layer, and the right-angle strain gauge is connected to a dynamic strain gauge to display the strain of the solder layer of the IGBT module due to power cycle heat generation on a PC; an infrared camera is arranged around the IGBT module to record the temperature of the IGBT module test piece at two moments of high and low power; both ends of the micro circular high temperature ceramic heater are also connected in parallel with the signal input end of the oscilloscope to detect the voltage on the ceramic heater to form a voltage waveform.

[0042] The time delay relay is a cyclic timing relay.

[0043] The right-angle strain gauge adopts a right-angle strain rosette that can withstand a temperature of -40-150°C and has medium temperature resistance, which can ensure that the strain gauge is basically not affected by temperature when the device is working, thereby ensuring the accuracy of the strain test. This embodiment adopts a right-angle strain rosette model ZF120-05CA(11)-Q100.

[0044] The method for measuring the temperature and stress of an IGBT module using the above-mentioned IGBT module temperature and stress testing device generated by power cycle heat comprises the following steps:

[0045] 1) Based on ANSYS APDL, an IGBT module simulation model is established and a cyclic power load is applied to it to obtain the simulated temperature and simulated stress values ​​of the IGBT module solder layer;

[0046] The specific dimensions of the simulation model are as follows: the substrate size is 58.5mm×45mm×1.5mm, 7 IGBT tubes are arranged on the substrate, the IGBT tube size is 10mm×15mm×4.4mm, the upper IGBT tube edge spacing is 1mm, and the lower chip edge spacing is 2mm; each IGBT power tube has three solder layers, two small ones and one large one, the size of the large solder layer is 10mm×10mm×0.4mm, the size of the small solder layer is 0.85mm×3mm×0.1mm, and there is a pad under the small solder layer, the size of which is 1.15mm×3mm×0.3mm.

[0047] 2) Obtain the total thermal power applied to the 7 chips on the IGBT module simulation model: In the simulation, the power applied to the chip is loaded in the form of density. Based on the power load applied in step 1), within 10 minutes, the power rises to 1.4e6w / m^3. When the power is 1.4e6w / m^3, the power is kept constant for 10 minutes, and then the power drops from 1.4e6w / m^3 to 0.8e6w / m^3 within 10 minutes. When the power is 0.8e6w / m^3, the power is kept constant for 10 minutes (this is one cycle), and then the power rises from 0.8e6w / m^3 to 1.4e6w / m^3 within 10 minutes. The cycle of one cycle is 2400s. Four cycles are performed in this way, and transient power analysis is performed. Finally, the total high and low cycle power applied to the 7 IGBT tubes is obtained by multiplying the power density by the total volume of the chip. ;

[0048] 3) Obtaining the output voltage value of the DC stabilized power supply: According to P=UI, n chips in the IGBT module correspond to n miniature circular high-temperature ceramic heating plates, and the miniature circular high-temperature ceramic heating plates are connected in series. By adjusting the output voltage of the DC stabilized power supply, the output voltage value of the DC stabilized power supply is obtained when the total thermal power is known;

[0049] Specifically, first connect 7 miniature circular high-temperature ceramic heating plates in series to the positive and negative ends of a DC stable power supply, and then, under known high and low power loading conditions, gradually adjust the output voltage of the DC stable power supply through the formula P=UI, and switch the displayed voltage and current values ​​through the display button on the DC stable power supply. According to the equal current value in the series circuit, the voltage values ​​on the 7 identical miniature circular high-temperature ceramic heating plates are equal, and finally adjust the high and low powers that need to be loaded on the ceramic heating plates.

[0050] 4) Making an IGBT module test sample, and opening a blind hole on the back of the chip of the IGBT module test sample that is large enough to place a right-angle strain gauge, and the solder layer can be seen;

[0051] Specifically, according to step 1), it can be determined on which chip's solder layer the maximum stress value appears under the condition of applying a cyclic power load, and then a hole is drilled on the back of the corresponding chip. A flat milling head with a diameter slightly larger than the right-angle strain gauge is used to drill a blind hole of a certain depth on a drilling machine so that the solder layer is just exposed.

[0052] 5) Paste the right-angle strain gauge on the solder layer, connect the right-angle strain gauge to the dynamic strain gauge through three signal output lines, and place 7 miniature circular high-temperature ceramic heating plates on the 7 chips of the IGBT module test sample, and connect the 7 miniature circular high-temperature ceramic heating plates in series between the delay relay and the DC stable power supply;

[0053] 6) Connect the overall physical circuit: connect the DC stable power supply, the delay relay, and the micro-circular high-temperature ceramic heating plate end to end to form a closed loop. After power is turned on, the micro-circular high-temperature ceramic heating plate heats up and plays a role in heating the chip, realizing the chip power cycle heat generation;

[0054] Specifically: first connect one output end of the DC stable power supply to the driving end of the delay relay to drive the delay relay module, and then connect the positive poles of the high-power output end and the low-power output end of the DC stable power supply to the two output ports of the output end of the delay relay respectively, and then connect the input port of the output end of the delay relay in series with 7 miniature circular high-temperature ceramic heating plates, and then connect the miniature circular high-temperature ceramic heating plates to the negative poles of the two output ends of the DC stable power supply.

[0055] 7) Connect the two ends of the oscilloscope to the overall physical circuit. First, calibrate the oscilloscope. Then connect the clip and hook at the signal input end of the oscilloscope in parallel to the two ends of the seven miniature circular high-temperature ceramic heating plates connected in series, with the hook connected to the positive electrode and the clip connected to the negative electrode, so as to detect the voltage on the seven miniature circular high-temperature ceramic heating plates and form a corresponding voltage waveform;

[0056] 8) Obtaining the temperature of the IGBT module test sample: According to the voltage waveform displayed by the oscilloscope in step 7), when the last cycle is reached, the temperature of the IGBT module test sample at high and low power moments is recorded by an infrared camera;

[0057] 9) Obtain the strain value of the solder layer of the IGBT module test sample: According to the right-angle strain gauge connected to the dynamic strain gauge, the strain values ​​of the solder layer measured by the three-axis right-angle strain gauge in the three directions of 0°, 45° and 90° under the plane stress state are displayed on the PC;

[0058] 10) Compare the actually measured temperature with the temperature obtained by simulation in step 1), and calculate the stress value obtained by the actually measured strain value using the strain rosette formula and compare it with the stress value obtained by simulation in step 2); the calculation formula of the stress value is as follows:

[0059]

[0060]

[0061]

[0062] Where σ1 is the maximum principal stress, σ3 is the minimum principal stress, ε1 is the maximum principal strain, and ε3 is the minimum principal strain; ε 0° , ε 45° and ε 90°They are the linear strains in three directions measured by the triaxial right-angle strain gauge under plane stress state; E is the elastic modulus; μ is the Poisson's ratio.

[0063] Example:

[0064] The method for measuring the temperature and stress of an IGBT module using the above-mentioned IGBT module temperature and stress testing device generated by power cycle heat specifically comprises the following steps:

[0065] 1) Establish an IGBT module simulation model based on ANSYS APDL. The simulation model is as follows Figure 2 As shown, a cyclic power load is applied to it. The cyclic power load is as follows Figure 3 As shown, the temperature and stress value of the solder layer of the IGBT module under high power are finally obtained. The temperature diagram obtained by simulation is shown in Figure 4 As shown in Figure 2, the stress diagram obtained by simulation is shown in Figure 2. Figure 5 shown.

[0066] 2) Obtain the total thermal power applied to the chip on the IGBT module. In the simulation, the power applied to the chip is loaded in the form of density. By multiplying the power density by the total volume of the chip, the total cyclic high and low powers applied to the 7 IGBT tubes are obtained. The high power of the total thermal power is 3.8808W, and the low power is 2.4276W.

[0067] 3) Obtain the output voltage value of the DC stabilized power supply. According to P=UI, 7 IGBT tubes correspond to 7 ceramic heating plates, and the ceramic heating plates are connected in series. By adjusting the output voltage of the DC stabilized power supply, the output voltage value of the DC stabilized power supply is obtained when the total thermal power is known. The voltage value corresponding to high power is 6.2V, and the voltage value corresponding to low power is 4.6V.

[0068] 4) Make an IGBT module test sample, and open a blind hole of a size large enough to accommodate a right-angle strain rosette on the back of the chip with the largest stress value in the IGBT module test sample, and see the solder layer. The actual sample is shown in the figure Figure 6 shown.

[0069] 5) Paste the right-angle strain rosette on the blind hole on the back of the IGBT module test sample, connect the right-angle strain rosette to the dynamic strain gauge through three signal output lines, and place 7 ceramic heating plates on the chip of the IGBT module test sample. Connect the 7 ceramic heating plates in series between the delay relay and the DC stable power supply. The sample after pasting the right-angle strain rosette is shown in the figure below. Figure 7 shown.

[0070] 6) Connect the overall physical circuit, connect the DC stable power supply with the delay relay and the ceramic heating plate end to end to form a closed loop. After power is turned on, the ceramic heating plate heats up to heat the chip, realizing the chip power cycle heat generation. The overall physical picture is as follows Figure 8 As shown, the overall circuit connection diagram is as follows Fig. 9 shown.

[0071] 7) Connect the two ends of the oscilloscope to the overall physical circuit, detect the voltage on the 7 ceramic heating plates, and form the corresponding voltage waveform. The oscilloscope output voltage waveform is shown in the figure below: Fig.10 shown.

[0072] 8) Obtain the temperature of the IGBT module test sample. According to the voltage waveform displayed by the oscilloscope in step 7), when the last cycle is reached, use an infrared camera to record the temperature of the IGBT module test sample at the high power moment. The temperature graph of the test sample is as follows: Fig.11 As shown, Fig.11 The value 71.4 shown in the upper right corner is the highest temperature.

[0073] 9) Obtain the strain value of the solder layer of the IGBT module test sample. At the same time as step 8), the strain values ​​in three directions measured are displayed on the PC according to the right-angle strain rosette connected to the dynamic strain gauge. The strain curve measured by the dynamic strain gauge is as follows: Fig.12 As shown, Fig.12 The strain values ​​in the three directions (0°, 45° and 90°) shown are:

[0074] ε 0° =129.31×10 -6 , ε 45° =-1767.84×10 -6 , ε 90° =-473.42×10 -6 .

[0075] 10) Compare the actual measured temperature with the simulated temperature: At room temperature, Fig.11 The measured maximum temperature is 71.4℃, which is 78.3545℃ compared with the maximum temperature obtained by finite element simulation. The relative error between the measured temperature and the simulated temperature is 9.74%. Within a certain error range, the measured results are relatively consistent with the simulation. The reason for the error is that the material parameters of each part in the simulation are different from the material parameters used in the actual sample. There is a certain thermal resistance from the heat source to the substrate, which leads to the corresponding error. The experimental results show that the simulation analysis results are consistent with the experimental results.

[0076] 11) Calculate the stress value obtained by the actual measured strain value through the strain rosette formula and compare it with the stress value obtained by simulation: Fig.12Substituting the strain values ​​in the three directions shown into the strain rosette formula, we can calculate: σ1=23.92556×10 6 pa,σ3=-37.4253×10 6 pa, combined with the area measured by the strain gauge in the actual measurement, the nodes of the solder layer in this area are selected in the simulation model, and the principal stress simulation values ​​of the nodes in the same area are 25.078MPa and -39.119MPa respectively. Comparing the simulation results with the experimental results, it can be seen that the error between the experimental and simulated principal stress results is 4.82% and 4.53% respectively. Within a certain error range, the measured results are relatively consistent with the simulation. The experimental results show that the simulation analysis results are consistent with the experimental results.

[0077] Table 1 IGBT model material parameters

[0078]

[0079] Table 2 SAC305 material parameters

[0080]

Claims

1. A method for measuring the temperature and stress of an IGBT module, using an IGBT module temperature and stress test device that generates heat through power circulation, the test device comprising a DC regulated power supply, a time delay relay and a miniature circular high-temperature ceramic heater connected in sequence; the miniature circular high-temperature ceramic heater is placed on the chip of the IGBT module to simulate chip heating; a blind hole is opened on the back of the chip of the IGBT module to expose the solder layer, a right-angle strain gauge is adhered to the solder layer, the right-angle strain gauge is connected to a dynamic strain gauge to display the strain of the IGBT module solder layer due to power circulation heat generation on a PC; an infrared camera is arranged around the IGBT module to record the temperature of the IGBT module test piece; both ends of the miniature circular high-temperature ceramic heater are also connected in parallel with the signal input end of the oscilloscope to detect the voltage on the ceramic heater to form a voltage waveform, characterized in that The steps include: 1) Based on ANSYS APDL, an IGBT module simulation model is established and a cyclic power load is applied to it to obtain the simulated temperature and simulated stress values ​​of the IGBT module solder layer; 2) Obtain the total thermal power applied to n chips on the IGBT module simulation model: The power applied to the chip in the simulation is loaded in the form of density. The total cyclic high and low power applied to the n chips in the IGBT module is obtained by multiplying the power density by the total volume of the chip; 3) Obtaining the output voltage value of the DC stabilized power supply: According to P=UI, n chips in the IGBT module correspond to n miniature circular high-temperature ceramic heating plates, and the miniature circular high-temperature ceramic heating plates are connected in series. By adjusting the output voltage of the DC stabilized power supply, the output voltage value of the DC stabilized power supply is obtained when the total thermal power is known; 4) Making an IGBT module test sample, and opening a blind hole on the back of the chip of the IGBT module test sample that is large enough to place a right-angle strain gauge, and the solder layer can be seen; 5) Paste the right-angle strain gauge on the solder layer, connect the right-angle strain gauge to the dynamic strain gauge through three signal output lines, and place n miniature circular high-temperature ceramic heating plates on the n chips of the IGBT module test sample, and connect the n miniature circular high-temperature ceramic heating plates in series between the delay relay and the DC stable power supply; 6) Connect the overall physical circuit: connect the DC stable power supply, the delay relay, and the micro-circular high-temperature ceramic heating plate end to end to form a closed loop. After power is turned on, the micro-circular high-temperature ceramic heating plate heats up and plays a role in heating the chip, realizing the chip power cycle heat generation; 7) Connect the two ends of the oscilloscope to the overall physical circuit, first calibrate the oscilloscope, then connect the clip and hook of the oscilloscope signal input end in parallel to the two ends of n miniature circular high-temperature ceramic heating plates connected in series, where the hook is connected to the positive electrode and the clip is connected to the negative electrode, so as to detect the voltage on the n miniature circular high-temperature ceramic heating plates and form a corresponding voltage waveform; 8) Obtaining the temperature of the IGBT module test sample: According to the voltage waveform displayed by the oscilloscope in step 7), when the last cycle is reached, the temperature of the IGBT module test sample at high and low power moments is recorded by an infrared camera; 9) Obtain the strain value of the solder layer of the IGBT module test sample: According to the right-angle strain gauge connected to the dynamic strain gauge, the strain values ​​of the solder layer measured by the three-axis right-angle strain gauge in the three directions of 0°, 45° and 90° under the plane stress state are displayed on the PC; 10) Compare the actually measured temperature with the temperature obtained by simulation in step 1), and calculate the stress value obtained by the actually measured strain value using the strain rosette formula and compare it with the stress value obtained by simulation in step 2).

2. The method for measuring temperature and stress of an IGBT module according to claim 1, characterized in that: The time delay relay is a cyclic timing relay.

3. The method for measuring temperature and stress of an IGBT module according to claim 1, characterized in that: The right-angle strain gauge adopts a right-angle strain rosette that can withstand a temperature of -40-150°C.

4. The method for measuring temperature and stress of an IGBT module according to claim 1, characterized in that: In step 3), the output voltage value of the DC stable power supply is obtained by first connecting n miniature circular high-temperature ceramic heating plates in series to the positive and negative ends of the DC stable power supply, and then gradually adjusting the output voltage of the DC stable power supply under known high and low power loading conditions through the formula P=UI. The display button on the DC stable power supply is used to switch the displayed voltage and current values. According to the equal current values ​​in the series circuit, the voltage values ​​on the n identical miniature circular high-temperature ceramic heating plates are equal, and finally the high and low powers that need to be loaded on the ceramic heating plates are adjusted.

5. The method for measuring temperature and stress of an IGBT module according to claim 1, characterized in that: In step 4), the preparation of the IGBT module test sample is specifically carried out according to step 1) to obtain the solder layer of which chip the maximum stress value appears under the condition of applying a cyclic power load, and then drilling a hole on the back of the corresponding chip, using a flat milling head with a diameter slightly larger than the right-angle strain gauge to drill a blind hole of a certain depth on a drilling machine so that the solder layer is just exposed.

6. The method for measuring temperature and stress of an IGBT module according to claim 1, characterized in that: In step 6), the connection of the overall physical circuit is specifically as follows: first, one output end of the DC stable power supply is connected to the driving end of the delay relay to drive the delay relay module, and then the positive poles of the high-power output end and the low-power output end of the DC stable power supply are respectively connected to the two output ports of the output end of the delay relay, and then the input port of the output end of the delay relay is connected in series with n miniature circular high-temperature ceramic heating plates, and then the miniature circular high-temperature ceramic heating plates are connected to the negative poles of the two output ends of the DC stable power supply.

7. The method for measuring temperature and stress of an IGBT module according to claim 1, characterized in that: In step 10), the calculation formula of the stress value is as follows: Where σ1 is the maximum principal stress, σ3 is the minimum principal stress, ε1 is the maximum principal strain, and ε3 is the minimum principal strain; ε0°, ε 45 ° and ε 90 ° is the linear strain in three directions measured by the triaxial right-angle strain gauge under plane stress state; E is the elastic modulus; μ is the Poisson's ratio.

Images