Temperature control method for IGBT testing

Abstract

The application relates to the technical field of semiconductors, and discloses a temperature control method for IGBT testing. The method comprises the following steps: acquiring a theoretical temperature Tj1 of an IGBT chip and a theoretical temperature T41 of an NTC; calculating a target power P2 of a heating device and a target temperature T42 of the NTC when the IGBT module is heated and tested; comparing the theoretical temperature T41 of the NTC with the target temperature T42 of the NTC; when the difference between the theoretical temperature T41 of the NTC and the target temperature T42 of the NTC exceeds an allowable range, adjusting the target power P2, so that the IGBT chip maintains a required target temperature Tj2. The actual temperature of the IGBT chip is characterized by the temperature of the NTC, so that the IGBT chip always maintains the required target temperature Tj2 when the IGBT module is tested, and the accurate and effective control of the junction temperature of the IGBT module is realized.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a temperature control method for IGBT testing. Background Technology

[0002] Currently, IGBTs (Insulated Gate Bipolar Transistors) are widely used. As a typical power semiconductor device, they have advantages such as simple drive circuits and a good balance between steady-state losses and switching losses. To improve the yield during the packaging stage, it is necessary to test the high-temperature leakage characteristics of the chips. However, accurately controlling the test temperature for high-temperature testing of IGBTs has always been a major challenge in the industry. If the temperature of the IGBT module cannot be accurately determined, the consistency of the test temperature cannot be guaranteed, and inconsistent test temperatures will lead to inconsistent quality across products.

[0003] Existing temperature measurement solutions for IGBT modules mostly rely on direct contact thermocouple wires. However, the measured temperature is affected by the heating fixture, the heat dissipation at the thermocouple contact point, and poor contact at the thermocouple contact point. This makes it impossible to accurately and effectively measure the temperature of the IGBT module. Furthermore, the IGBT module generates heat during testing, which affects its internal junction temperature, resulting in test values ​​that cannot accurately reflect the actual situation. Summary of the Invention

[0004] This invention provides a temperature control method for IGBT testing, to solve the technical problem that existing methods cannot accurately and effectively control the junction temperature of IGBT modules.

[0005] This invention proposes a temperature control method for IGBT testing, comprising the following steps:

[0006] The system measures and acquires a first set of data to characterize the operating parameters of the IGBT high-temperature test system in its first state without an IGBT module installed; it acquires the theoretical temperature Tj1 of the IGBT chip and the theoretical temperature T41 of the NTC; based on the first set of data, the theoretical temperature Tj1 of the IGBT chip, and the theoretical temperature T41 of the NTC, it calculates a second set of data to characterize the thermal resistance of the IGBT high-temperature test system in its second state with an IGBT module installed and under heating; based on the target temperature Tj2 of the IGBT chip required for testing the IGBT module, and in conjunction with the second set of data, it calculates the... The IGBT high-temperature testing system, in its third state where an IGBT module is loaded and heating and testing are being performed, specifies the target power P2 of the heating device and the target temperature T42 of the NTC. In this third state, the heating device is controlled to heat the IGBT module at the target power P2. The theoretical temperature T41 of the NTC and the target temperature T42 of the NTC are compared. When the difference between the theoretical temperature T41 and the target temperature T42 of the NTC exceeds the allowable range, the target power P2 is adjusted so that the IGBT chip maintains the required target temperature Tj2 during the testing of the IGBT module.

[0007] Furthermore, the first data set includes: ambient temperature Ta, heating device temperature T1, heating fixture temperature T2, IGBT module housing temperature T3, and NTC resistance R. NTC Voltage V C Current I C And the theoretical power P1 of the heating device.

[0008] Furthermore, the step of obtaining the theoretical temperature Tj1 of the IGBT chip includes:

[0009] The minimum current I was measured using the IGBT high-temperature testing system. C voltage V C Based on formula V C =K×Tj1, calculate the theoretical temperature Tj1 of the IGBT chip; in the above formula, K is a known constant.

[0010] Furthermore, the steps for obtaining the theoretical temperature T41 of the NTC include:

[0011] Based on the resistor R of the NTC NTC Based on the known RT conversion formula, the theoretical temperature T41 of the NTC is calculated.

[0012] Furthermore, the second data group includes thermal resistance R1 from the heating device to the heating fixture, thermal resistance R2 from the heating fixture to the IGBT module housing, thermal resistance R3 from the IGBT module housing to the NTC, thermal resistance R4 from the NTC to the IGBT chip, and thermal resistance R5 from the heating device to the air.

[0013] Further, the step of calculating the second data set includes, based on the following formula:

[0014] T2 = T1 - R1 × P1;

[0015] T3 = T2 - R2 × P1;

[0016] T41 = T3 - R3 × P1;

[0017] Tj1 = T41 - R4 × P1;

[0018] Ta = T1 - R5 × P1;

[0019] A thermal resistance model with a fixed thermal resistance was established. After multiple heating and testing and fitting, the values ​​of R1, R2, R3, R4, and R5 were calculated.

[0020] Further, the step of calculating the target power P2 of the heating device includes calculating the value of the target power P2 based on the formula Tj2=Ta-(R1+R2+R3+R4-R5)×P2.

[0021] Further, the step of calculating the target temperature T42 of the NTC includes calculating the value of the target temperature T42 based on the formula Tj2=T42-R4×P2.

[0022] Furthermore, when the difference between the theoretical temperature T41 and the target temperature T42 of the NTC exceeds the allowable range, the step of adjusting the target power P2 includes:

[0023] When the target temperature T42 of the NTC is greater than the theoretical temperature T41 of the NTC, the target power P2 of the heating device is reduced to the equilibrium power P3, wherein the equilibrium power P3 is calculated using the following formula:

[0024] P3 = P2 × [(T42 - T41) ÷ T41]

[0025] Until the difference between the theoretical temperature T41 and the target temperature T42 of the NTC is within the allowable range.

[0026] Furthermore, when the difference between the theoretical temperature T41 and the target temperature T42 of the NTC exceeds the allowable range, the step of adjusting the target power P2 further includes:

[0027] When the target temperature T42 of the NTC is less than the theoretical temperature T41 of the NTC, the target power P2 of the heating device is increased.

[0028] The beneficial effects of the technical solution provided by this invention include: by adjusting the target power P2 of the heating device during IGBT module testing, the target temperature T42 of the IGBT module's NTC is made as close as possible to the theoretical temperature T41 of the NTC. The temperature of the NTC is used to characterize the actual temperature of the IGBT chip, ensuring that the IGBT chip always maintains the required target temperature Tj2 during IGBT module testing. This achieves accurate and effective control of the IGBT module junction temperature, ensuring temperature consistency of the IGBT module during high-temperature testing and guaranteeing the reliability of the IGBT module quality. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic flowchart of the temperature control method for IGBT testing according to the present invention. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 embodiments of the present invention, not all embodiments. 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.

[0032] like Figure 1 The temperature control method shown for IGBT testing includes the following steps:

[0033] S1. Measure and acquire the first set of data used to characterize the system's operating parameters in the first state of the IGBT high-temperature test system when the IGBT module is not loaded.

[0034] The first data set includes: ambient temperature Ta, heating device temperature T1, heating fixture temperature T2, IGBT module housing temperature T3, and NTC resistance R. NTC Voltage V C Current I C And the theoretical power P1 of the heating device.

[0035] The acquisition results of the first data set mentioned above were obtained using existing technology. In this embodiment, the IGBT high-temperature testing system uses an existing system. The heating device includes the heating rod of the IGBT high-temperature testing system.

[0036] S2. Obtain the theoretical temperature Tj1 of the IGBT chip and the theoretical temperature T41 of the NTC.

[0037] The steps to obtain the theoretical temperature Tj1 of the IGBT chip include:

[0038] The minimum current I was measured using an IGBT high-temperature testing system. C voltage V C Based on formula V C =K × Tj1, calculate the theoretical temperature Tj1 of the IGBT chip; in the above formula, K is a known constant. Those skilled in the art know that the value of K can be found in the IGBT module's product manual. The minimum current I mentioned above... C This refers to the current at which the IGBT module will not heat up when the IGBT high-temperature testing system is operating. In other words, when the current I... C The IGBT module is small enough that it will not overheat; measure the corresponding voltage V at this time. C This can be understood as the theoretical temperature Tj1 of the IGBT chip being the theoretical value of the IGBT module in a non-test state. The purpose of this theoretical temperature Tj1 is to calculate the thermal resistance R4 from the NTC to the IGBT chip.

[0039] The steps to obtain the theoretical temperature T41 of NTC include:

[0040] Based on the measured resistance R of the NTC NTC Based on the RT conversion formula provided by the NTC supplier, the theoretical temperature T41 of the NTC is calculated.

[0041] S3. Based on the first data set, the theoretical temperature Tj1 of the IGBT chip, and the theoretical temperature T41 of the NTC, calculate the second data set used to characterize the thermal resistance of the IGBT high-temperature test system in the second state where the IGBT module is loaded and heated.

[0042] The second data set includes the thermal resistance R1 from the heating device to the heating fixture, the thermal resistance R2 from the heating fixture to the IGBT module housing, the thermal resistance R3 from the IGBT module housing to the NTC, the thermal resistance R4 from the NTC to the IGBT chip, and the thermal resistance R5 from the heating device to the air.

[0043] The second data set is calculated based on the following formula:

[0044] T2 = T1 - R1 × P1;

[0045] T3 = T2 - R2 × P1;

[0046] T41 = T3 - R3 × P1;

[0047] Tj1 = T41 - R4 × P1;

[0048] Ta = T1 - R5 × P1;

[0049] Since the ambient temperature Ta, the temperature T1 of the heating device, the temperature T2 of the heating fixture, the temperature T3 of the IGBT module casing, and the theoretical power P1 of the heating device in the first data set can all be considered as known values.

[0050] By establishing a fixed thermal resistance model, and performing multiple heating and testing tests and fitting, the values ​​of R1, R2, R3, R4, and R5 in the above formula can be calculated.

[0051] S4. Based on the target temperature Tj2 of the IGBT chip required when testing the IGBT module, and in conjunction with the second data set, calculate the target power P2 of the heating device and the target temperature T42 of the NTC in the third state of the IGBT high temperature test system when the IGBT module is loaded and heating and testing are performed.

[0052] Specifically, the target power P2 of the heating device is calculated based on the following formula:

[0053] Tj2=Ta-(R1+R2+R3+R4-R5)×P2

[0054] In the above formula, Tj2 is the target value given when testing the IGBT module using the IGBT high-temperature testing system, that is, the temperature value that the IGBT chip is expected to maintain throughout the IGBT module testing. This ensures that the temperature of the IGBT module is consistent during high-temperature testing, guaranteeing the reliability of the IGBT module quality.

[0055] The ambient temperature Ta is a known value from the first data set. The values ​​of R1, R2, R3, R4, and R5 have also been calculated, so given the specific target temperature Tj2, the target power P2 can be determined.

[0056] The target temperature T42 of the NTC is calculated based on the following formula:

[0057] Tj2=T42-R4×P2

[0058] In the above formula, Tj2 is a target value given when testing the IGBT module using the IGBT high-temperature testing system, and it is a known value. The values ​​of R4 and the target power P2 have already been obtained in the previous calculations. Therefore, the target temperature T42 of the NTC can be directly determined.

[0059] S5. After obtaining the above values, start the heating test of the IGBT module.

[0060] In the third state, where the IGBT high-temperature testing system is equipped with an IGBT module and is undergoing heating and testing, the heating device is controlled to heat the IGBT module at the target power P2.

[0061] Compare the theoretical temperature T41 of the NTC with the target temperature T42 of the NTC.

[0062] When the difference between the theoretical temperature T41 and the target temperature T42 of the NTC exceeds the allowable range (which can be -0.1℃ to +0.1℃), the target power P2 is adjusted so that the IGBT chip maintains the required target temperature Tj2 when the IGBT module is tested.

[0063] For example, when the target temperature T42 of the NTC is greater than the theoretical temperature T41 of the NTC, the difference between the theoretical temperature T41 and the target temperature T42 of the NTC is greater than 1℃. The target power P2 of the heating device is reduced to the equilibrium power P3, where the formula for calculating the equilibrium power P3 is:

[0064] P3 = P2 × [(T42 - T41) ÷ T41]

[0065] Until the difference between the theoretical temperature T41 and the target temperature T42 of the NTC is within the allowable range.

[0066] When the target temperature T42 of the NTC is less than the theoretical temperature T41 of the NTC, the target power P2 of the heating device is increased.

[0067] Since the temperature of the IGBT chip is difficult to obtain, the target power P2 of the heating device during IGBT module testing is adjusted to make the target temperature T42 of the IGBT module's NTC as close as possible to the theoretical temperature T41 of the NTC. The temperature of the NTC is used to characterize the actual temperature of the IGBT chip, so that the IGBT chip always maintains the required target temperature Tj2 during IGBT module testing. This achieves accurate and effective control of the IGBT module junction temperature, ensuring temperature consistency of the IGBT module during high-temperature testing and guaranteeing the reliability of the IGBT module quality.

[0068] In the description of this invention, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0069] It should be noted that in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0070] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features of the invention herein.

Claims

1. A temperature control method for IGBT testing, characterized in that, Includes the following steps: The first set of data used to characterize the operating parameters of the IGBT high-temperature test system is obtained in the first state when the IGBT module is not loaded. Obtain the theoretical temperature Tj1 of the IGBT chip and the theoretical temperature T41 of the NTC; Based on the first data set, the theoretical temperature Tj1 of the IGBT chip and the theoretical temperature T41 of the NTC, the second data set used to characterize the thermal resistance of the IGBT high temperature test system in the second state where the IGBT module is loaded and heated is calculated. Based on the target temperature Tj2 of the IGBT chip required when testing the IGBT module, and in conjunction with the second data set, the target power P2 of the heating device and the target temperature T42 of the NTC of the IGBT high temperature test system in the third state when the IGBT module is loaded and heating and testing are performed are calculated. In the third state, the heating device is controlled to heat the IGBT module at the target power P2; Compare the theoretical temperature T41 of the NTC with the target temperature T42 of the NTC; when the difference between the theoretical temperature T41 and the target temperature T42 of the NTC exceeds the allowable range, adjust the target power P2 so that the IGBT chip maintains the required target temperature Tj2 when testing the IGBT module.

2. The temperature control method for IGBT testing as described in claim 1, characterized in that, The first data set includes: ambient temperature Ta, heating device temperature T1, heating fixture temperature T2, IGBT module housing temperature T3, and NTC resistance R. NTC Voltage V C Current I C And the theoretical power P1 of the heating device.

3. The temperature control method for IGBT testing as described in claim 2, characterized in that, The steps for obtaining the theoretical temperature Tj1 of the IGBT chip include: The minimum current I was measured using the IGBT high-temperature testing system. C voltage V C Based on formula V C =K Tj1 is used to calculate the theoretical temperature Tj1 of the IGBT chip; in the above formula, K is a known constant.

4. The temperature control method for IGBT testing as described in claim 3, characterized in that, The steps for obtaining the theoretical temperature T41 of the NTC include: Based on the resistor R of the NTC NTC Based on the known RT conversion formula, the theoretical temperature T41 of the NTC is calculated.

5. The temperature control method for IGBT testing as described in claim 4, characterized in that, The second data group includes the thermal resistance R1 from the heating device to the heating fixture, the thermal resistance R2 from the heating fixture to the IGBT module housing, the thermal resistance R3 from the IGBT module housing to the NTC, the thermal resistance R4 from the NTC to the IGBT chip, and the thermal resistance R5 from the heating device to the air.

6. The temperature control method for IGBT testing as described in claim 5, characterized in that, The steps for calculating the second data set include, based on the following formula: T2=T1-R1 P1; T3=T2-R2 P1; T41=T3-R3 P1; Tj1=T41-R4 P1; Ta=T1-R5 P1; A thermal resistance model with a fixed thermal resistance was established. After multiple heating and testing and fitting, the values ​​of R1, R2, R3, R4, and R5 were calculated.

7. The temperature control method for IGBT testing as described in claim 6, characterized in that, The step of calculating the target power P2 of the heating device includes using the formula Tj2=Ta-(R1+R2+R3+R4-R5). The target power P2 is calculated using P2.

8. The temperature control method for IGBT testing as described in claim 7, characterized in that, The steps for calculating the target temperature T42 of the NTC include, based on the formula Tj2=T42-R4 P2 calculates the value of the target temperature T42.

9. The temperature control method for IGBT testing as described in claim 8, characterized in that, When the difference between the theoretical temperature T41 and the target temperature T42 of the NTC exceeds the allowable range, the step of adjusting the target power P2 includes: When the target temperature T42 of the NTC is greater than the theoretical temperature T41 of the NTC, the target power P2 of the heating device is reduced to the equilibrium power P3, wherein the equilibrium power P3 is calculated using the following formula: Until the difference between the theoretical temperature T41 and the target temperature T42 of the NTC is within the allowable range.

10. The temperature control method for IGBT testing as described in claim 9, characterized in that, When the difference between the theoretical temperature T41 and the target temperature T42 of the NTC exceeds the allowable range, the step of adjusting the target power P2 further includes: When the target temperature T42 of the NTC is less than the theoretical temperature T41 of the NTC, the target power P2 of the heating device is increased.

Images