Method and device for detecting aging-related damage or delamination on components, in particular power modules of power electronics and power electronics, in particular converters

Abstract

In order to enable reliable detection of aging-related damage or delamination on components, such as power modules used in power electronics or converters, which detection allows a sufficiently precise prediction of the remaining operating life of the component or power module, it is proposed that: [i] in the course of a high-frequency reflection measurement, the component (BT), in particular the power module (LM), is scanned point by point, one-dimensionally or two-dimensionally, by irradiating a high-frequency signal in the microwave or millimeter wave range and by measuring at least one reflection signal (RSI) reflected on the component (BT, LM) as a result of the high-frequency signal radiation, in order to generate, in particular on the basis of a mathematical method for image reconstruction, at least one first high-frequency image (HFA1); [i i] scanning the component (BT, LM) point by point, one-dimensionally or two-dimensionally, by a combination of ultrasound signal radiation and high-frequency signal radiation in the microwave or millimeter wave range, directly time-shifted with the high-frequency signal radiation, and by measuring at least one other reflection signal (RSI') reflected on the component (BT, LM) as a result of the ultrasound signal and the high-frequency signal radiation, to generate at least one second high-frequency image (HFA2); and [iii] comparing the high-frequency images (HFA1, HFA2) generated based on the reflection signals (RSI, RSI'), wherein changes detected in the high-frequency images (HFA1, HFA2) indicate damage or delamination on the component (BT, LM).

Description

Technical Field

[0001] The invention relates to: a method for detecting aging-related damage or delamination on a component, in particular a power module of a power electronic device, according to the preamble of patent claim 1; a device for detecting aging-related damage or delamination on a component, in particular a power module of a power electronic device, according to the preamble of patent claim 6; and a power electronic device, in particular a converter, according to the preamble of patent claim 13. Background Art

[0002] In principle, ageing-related damage or delamination can be observed in components of various material properties or compositions that are subjected to continuous or cyclically changing physical loads under given use or operating conditions. Thus, in power electronics, such as power modules in converters, such as "insulated gate bipolar transistors" <igbt>The module ages due to normal operation within its specified operating range. This aging is primarily caused by numerous load cycles of heating and cooling during operation, which lead to a gradual destruction of the chip solder layer beneath the semiconductor chip and fatigue of the bonding wires and chip metallization that conduct the current to the switching and rectifying chip. Typical error mechanisms that occur in this regard are bond lift-off, heel cracks, and solder fatigue of the chip and system solder.

[0003] Therefore, a reliable aging determination of components, in particular power modules in power electronics such as converters, which allows a sufficiently precise prediction of the remaining operating service life, is of interest.

[0004] With the help of radar, electrical and mechanical changes associated with aging can be detected. To this end, changes in the reflection of components or power modules in the microwave or millimeter wave range must be monitored over a period of up to 30 years. However, radar systems are usually not stable over this period of time, so that it is not possible to compare HF reference measurements with measurements in an aged operating state. Therefore, due to the drift of the radar system, reliable aging determination is not easy to achieve.

[0005] In application areas where failure of components or power modules must be avoided, such as in converters in offshore wind farms, in traction applications, etc., there are various approaches to solving the problem, either through maintenance, redundancy or preventive replacement of components or power modules in the event of failure. Here, thermal models and accelerated service life tests can be used to infer the expected and already consumed service life. However, these calculations are subject to large errors due to the models used.

[0006] As for power modules, some power module manufacturers, for example, provide IGBT modules that contain diodes integrated as temperature sensors for IGBT chips. <igbt>"Aging can be indirectly inferred from the increase in temperature.

[0007] To date, there are no commercial solutions for condition monitoring of power modules in converters for service life prediction.

[0008] To compensate for drift in HF network analyzers, calibration devices are provided which recalibrate the system before each measurement. However, there are currently no commercial radar applications with long-term stability of several years. Summary of the invention

[0009] The object on which the present invention is based is to specify a method and a device for detecting aging-related damage or delamination on components, in particular power modules of power electronics and power electronics, in particular converters, by means of which method or device reliable detection of aging-related damage or delamination on components, such as power modules used in power electronics or converters, is possible, which detection allows a sufficiently precise prediction of the remaining operating service life of the component or the power module.

[0010] This object is achieved on the basis of the detection method defined in the preamble of patent claim 1 by the features specified in the characterizing part of patent claim 1 .

[0011] This object is also achieved on the basis of the detection device defined in the preamble of patent claim 6 by the features specified in the characterizing part of patent claim 6 .

[0012] This object is also achieved on the basis of the power electronics device defined in the preamble of patent claim 13 by the features specified in the characterizing part of patent claim 13 .

[0013] The invention according to independent claims 1, 6 and 13 is based on the idea that:

[0014] 1) in the course of a high-frequency reflection measurement, scanning the component, in particular a power module, point by point, one-dimensionally or two-dimensionally by irradiating a high-frequency signal in the microwave or millimeter wave range and by measuring at least one reflection signal reflected on the component as a result of the irradiation of the high-frequency signal, in order to generate at least one first high-frequency image, in particular based on a mathematical method for image reconstruction;

[0015] 2) scanning the component point by point, one-dimensionally or two-dimensionally, by combining ultrasound signal radiation with high-frequency signal radiation in the microwave or millimeter wave range and by measuring at least one further reflection signal reflected on the component as a result of the ultrasound signal and the high-frequency signal radiation, in order to generate at least one second high-frequency image, directly offset in time from the high-frequency signal radiation; and

[0016] 3) Comparing high-frequency images generated based on the reflection signals, wherein changes detected in the high-frequency images indicate damage or delamination on the component.

[0017] In the case of power modules in particular, aging gradually occurs during decades of electrical operation. According to the invention, preferably in the case of a combination of ultrasonic signal radiation and high-frequency signal radiation in the microwave or millimeter wave range, the reflection signals reflected at the power module should be measured in the case of this combination of ultrasonic signal radiation and high-frequency signal radiation, i.e. under ultrasonic excitation, and these reflection signals should be compared with a temporally subsequent HF measurement in which only the high-frequency signal is radiated, i.e. without ultrasonic excitation.

[0018] The changes in the reflection signal and the high-frequency image observed in this way are directly sensitive to damage or delamination in the power module. Since these measurements are carried out in succession in time, no complex drift correction of the HF measurement system that performs these measurements is required, and the changes in the reflection signal and the high-frequency image are directly related to damage or delamination in the power module and can thus be used to infer aging. Aging of power modules occurs primarily at the location of power semiconductors, such as IGBT chips or diodes.

[0019] Ultrasound-based radiation occurs at frequencies of typically 10-200 kHz, whereas high-frequency signal radiation occurs in a narrowband in the multi-GHz range. In this case, the combined interaction of ultrasound and high frequency can be detected as sidebands of the high-frequency signal.

[0020] For the irradiation of the ultrasonic signals, which preferably takes place according to claims 5 and 12 directly in the base region of the power module, at least one sonotrode is preferably used according to claims 4 and 11 .

[0021] Ultrasonic signal radiation is very sensitive to local cracks in the connection layers of the power module, especially welded and bonded. According to fatigue in the bonding and welding connection planes, these damaged planes are excited to form different local geometric vibrations in the ultrasonic range. Preferably, the scanning by high-frequency radiation in the microwave or millimeter wave range is carried out two-dimensionally, wherein preferably two high-frequency images are generated based on mathematical methods for image reconstruction, a first high-frequency image is generated once without ultrasonic signal radiation and a second high-frequency image is generated once with ultrasonic signal radiation. Here, according to claim 7, a high-frequency antenna device with multiple antennas is preferably provided, which scans the power module in rows and columns, wherein each antenna is alternately used as or acts as a transmitter and a receiver and the duration of acting / acting as a receiver is a multiple of the duration of acting / acting as a transmitter related to the number of antennas in the high-frequency antenna device. According to claim 8, the high-frequency antenna device is preferably designed as an antenna array or a T-shaped device. In the transmitting antenna function, the high-frequency signal is wirelessly coupled into the power module, and in the receiving antenna function, the reflected signal is measured with multiple antennas. The measured reflection characteristics change due to the initiation of thermomechanical cracks in the bonding wires and solder during electrical operation of the power module. By irradiating and detecting with an antenna array, a corresponding high-frequency image of the power module can be generated in the microwave or millimeter wave range.

[0022] These high-frequency images can be calculated using mathematical methods for image reconstruction from the reflected signals received at the HF antenna arrangement in the combined frequency band of the ultrasound.

[0023] In the case of two-dimensional scanning, the changes in the high-frequency image according to claims 2 and 9 are preferably presented as a difference image, with which the location and extent of damage or delamination on the component or power module can be selectively quantified. In this way, aged areas on the component or power module are highlighted as aging increases by areas without local damage.

[0024] In this case, preferably according to claims 3 and 10 , damage or delamination on the component or power module is indicated by the maximum amplitude in the difference image.

[0025] Due to the permanent drift of radar systems in the microwave or millimeter wave range, long-term changes on components or power modules can only be identified with considerable effort. Through the combination of ultrasonic signal radiation and high-frequency signal radiation in the microwave or millimeter wave range, aging-related damage or delamination on components, especially power modules, can be directly detected. The drift of HF measurement systems, also called radar systems, does not have to be corrected in a costly manner, because HF measurements with and without ultrasound that are close to each other in time are compared. The requirements for HF systems and measuring electronics are much lower than in the case of drift-corrected construction. Through the selective high-frequency image of damage or delamination, much higher measurement accuracy and dynamics of the measuring method can be achieved. In addition, it is no longer necessary to perform costly drift correction to monitor the service life of components or power modules over a period of several years or even decades, wherein preferably monitoring is performed at periodic intervals of aging power modules. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Further advantages of the invention emerge from the following description of an exemplary embodiment of the invention with reference to the single figure. DETAILED DESCRIPTION

[0027] The figure shows a device VG for detecting age-related damage or delamination on a power module LM of a power electronics device LEG. However, instead of a power module LM, any other component BT can also be checked for the occurrence of age-related damage or delamination and the occurrence of age-related damage or delamination can be detected. The power electronics device LEG is, for example, a converter in which the device VG described in more detail below is contained.

[0028] The device VG includes a high-frequency antenna device HFAO designed to transmit and receive signals, which during the high-frequency reflection measurement scans the power module LM, BT point by point, one-dimensionally or two-dimensionally by radiating a high-frequency signal in the microwave or millimeter wave range and by measuring at least one reflection signal RSI reflected on the power module LM, BT due to the high-frequency signal radiation. The high-frequency signal radiation is carried out based on the high-frequency signal provided by the high-frequency signal device HFSE. In this case, the high-frequency signal device HFSE can be a component of the device VG, as shown in the figure, or it can be assigned to the device externally instead.

[0029] The number of antennas contained in a high-frequency antenna arrangement HFAO for transmitting and receiving signals depends on the manner in which the scanning is ultimately to be carried out.

[0030] For point-by-point scanning, at least two antennas are required, one antenna is used as a transmitting antenna, and the other antenna is used as a receiving antenna. The high-frequency signal is radiated in the microwave or millimeter wave range on the power module LM, BT through the transmitting antenna, and the reflected signal RSI reflected by the high-frequency signal radiation on the power module LM, BT is measured through the receiving antenna. Then, an antenna transformation occurs, the transmitting antenna becomes the receiving antenna and the receiving antenna becomes the transmitting antenna.

[0031] For one-dimensional scanning, multiple antennas arranged in a row are required, wherein each antenna in the row is used or acts alternately as a transmitter and a receiver, and the duration of the time of acting as a receiver is a multiple of the duration of the time of acting as a transmitter related to the number of antennas arranged in the row in the high-frequency antenna device HFAO.

[0032] In the following, how this alternating use or function as a transmitter and a receiver of different durations generally functions in a preferred implementation form of this embodiment shall be described based on the high-frequency antenna device HFAO shown in the figure with an antenna array for two-dimensional scanning, the antenna array comprising a plurality of antennas A x1 ...A x8 and A y1 ...A y8 Alternatively, the high-frequency antenna arrangement HFAO can also be designed as a T-shaped arrangement instead of as an antenna array. In the case of two-dimensional scanning, the power modules LM, BT are scanned in rows and columns, each antenna again being used or acting alternately as a transmitter and a receiver, and here - as will be shown later - the duration of the function / acting as a receiver is a multiple of the duration of the function / acting as a transmitter in relation to the number of antennas in the high-frequency antenna arrangement HFAO.

[0033] In the case shown in FIG. 1 , in the first scanning step, the antenna A x1 To radiate a first high-frequency signal in the microwave or millimeter wave range on the power modules LM, BT, and transmit the first high-frequency signal through the other antenna A x2 ...A x8 and A y1 ...A y8 To measure the reflected signal RSI reflected by the high frequency signal radiation on the power modules LM and BT. Then, for the second scanning step, the antenna is changed, and the antenna A x1 becomes a receiving antenna and antenna A x2 In the second scanning step, antenna A x2 To radiate a second high-frequency signal in the microwave or millimeter wave range on the power modules LM, BT and transmit the signal through the other antenna A x1 , A x3 ...A x8 and A y1 ...A y8 To measure the reflected signal RSI reflected by the high-frequency signal radiation on the power module LM, BT. According to this principle, the antenna A x1 ...A x8 and A y1 ...A y8 Each antenna in the HFAO becomes a transmitting antenna once, while all other antennas become receiving antennas accordingly. Scanning information S-IF is formed from these reflection signals RSI measured by the high-frequency antenna arrangement HFAO.

[0034] The device VG now also includes a generation device EE for generating high-frequency images, which is connected to the high-frequency antenna device HFAO. The scanning information is transferred from the high-frequency antenna device HFAO to the generation device EE. In the generation device EE, at least one first high-frequency image HFA1 is generated based on the scanning information S-IF provided by the high-frequency antenna device HFAO. Preferably, this generation of the first high-frequency image HFA1 is carried out based on a mathematical method for image reconstruction.

[0035] Also included in the device VG is an ultrasonic signaling device USSE, which together with the high-frequency antenna device HFAO and the generating device EE forms a functional unit FE. The ultrasonic signaling device USSE preferably includes at least one sonotrode.

[0036] The functional unit FE formed is designed with regard to its function so that the power modules LM, BT are scanned point by point, one-dimensionally or two-dimensionally, directly with a time offset from the above-mentioned high-frequency signal radiation - which would mean immediately after the high-frequency signal radiation in the microwave or millimeter wave range and the two-dimensional scanning of the power modules LM, BT by measuring the reflection signal RSI to produce the first high-frequency image HFA1 - by a combination of the ultrasonic signal radiation radiated by the ultrasonic signal device USSE and the high-frequency signal radiation in the microwave or millimeter wave range as described above and by measuring at least one other reflection signal RSI' which is reflected on the power module LM, BT due to the combination of the ultrasonic signal and high-frequency signal radiation.

[0037] The ultrasonic oscillator radiates the ultrasonic signal directly in the bottom region of the power module LM.

[0038] This scanning is carried out similarly to the case of a single, previously described radio-frequency signal radiation in the microwave or millimeter wave range. Based on the other reflection signals RSI' measured by the high-frequency antenna device HFAO, other scanning information S-IF' is formed. These other scanning information are again transferred from the high-frequency antenna device HFAO to the generation device EE. In the generation device EE, at least one second high-frequency image HFA2 is generated based on the other scanning information provided by the high-frequency antenna device HFAO. Preferably, this generation of the second high-frequency image HFA2 is also carried out based on a mathematical method for image reconstruction.

[0039] Finally, the device VG also includes a comparison device VGE, which is connected to the generation device EE and functionally cooperates with the functional unit FE by comparing high-frequency images HFA1, HFA2 generated on the basis of the reflection signals RSI, RSI', wherein changes detected in these high-frequency images HFA1, HFA2 indicate damage or delamination on the power module LM, BT.

[0040] The comparison can preferably be such that changes detected in the high-frequency images HFA1, HFA2 in the case of a two-dimensional scan are presented in a difference image, using the position and extent of damage or delamination on the power module LM, BT. Thus, for example, damage or delamination on the power module LM, BT can be indicated by the maximum amplitude in the difference image. In other words: there is a damage indicator, using which damage can be determined based on the maximum local amplitude of the difference image.< / igbt> < / igbt>

Claims

1. A method for detecting aging-related damage or delamination on a component (BT), wherein during high-frequency reflection measurement, the component (BT) is scanned point by point, one-dimensionally or two-dimensionally by irradiating a high-frequency signal in the microwave or millimeter wave range and by measuring at least one reflection signal (RSI) reflected on the component (BT) as a result of the high-frequency signal radiation, to generate at least one first high-frequency image (HFA1), It is characterized in that a) scanning the component (BT) point by point, one-dimensionally or two-dimensionally, with a direct time offset to the high-frequency signal radiation, by combining ultrasound signal radiation with high-frequency signal radiation in the microwave or millimeter wave range and by measuring at least one further reflection signal (RSI') reflected at the component (BT) by the ultrasound signal and the high-frequency signal radiation, in order to generate at least one second high-frequency image (HFA2), b) comparing a first and a second high-frequency image (HFA1, HFA2) generated on the basis of the reflection signals (RSI, RSI'), wherein changes detected in the high-frequency images (HFA1, HFA2) indicate damage or delamination on the component (BT).

2. The method according to claim 1, characterized in that The component is a power module (LM) of a power electronics device.

3. The method according to claim 1, characterized in that The generation of the at least one first high-frequency image (HFA1) is based on a mathematical method for image reconstruction.

4. The method according to claim 1, characterized in that: In the case of a two-dimensional scan, the position and extent of damage or delamination on the component (BT) are explained using a difference image representing changes in the high-frequency images (HFA1, HFA2).

5. The method according to claim 4, characterized in that Damage or delamination on the component (BT) is indicated by the maximum amplitude in the difference image.

6. The method according to any one of claims 1 to 5, characterized in that At least one sonotrode is used for the ultrasonic signal radiation.

7. The method according to claim 6, characterized in that If the component (BT) is a power module (LM), the ultrasonic signal radiation is radiated directly in the base region of the power module (LM).

8. A device (VG) for detecting aging-related damage or delamination on a component (BT), comprising: a high-frequency antenna device (HFAO) designed for transmitting and receiving, which in the course of a high-frequency reflection measurement scans the component (BT) point by point, one-dimensionally or two-dimensionally by irradiating a high-frequency signal in the microwave or millimeter wave range and by measuring at least one reflection signal (RSI) reflected on the component (BT) as a result of the high-frequency signal radiation; and a generation device (EE) for generating a high-frequency image, which generates at least one first high-frequency image (HFA1) based on the scanning information (S-IF) provided by the high-frequency antenna device (HFAO), Features a) an ultrasonic signal device (USSE), which together with the high-frequency antenna device (HFAO) and the generating device (EE) forms a functional unit (FE), and wherein the functional unit (FE) is designed to scan the component (BT) point by point, one-dimensionally or two-dimensionally, directly with a time offset from the high-frequency signal radiation by a combination of the ultrasonic signal radiation radiated by the ultrasonic signal device (USSE) and the high-frequency signal radiation in the microwave or millimeter wave range and by measuring at least one further reflection signal (RSI') reflected at the component (BT) by the ultrasonic signal and the high-frequency signal radiation, and to generate at least one second high-frequency image (HFA2) based on further scanning information (S-IF') provided by the high-frequency antenna device (HFAO); b) a comparison device (VGE) which cooperates functionally with the functional unit (FE) by comparing first and second high-frequency images (HFA1, HFA2) generated on the basis of the reflection signals (RSI, RSI'), wherein changes detected in the high-frequency images (HFA1, HFA2) indicate damage or delamination on the component (BT).

9. Device (VG) according to claim 8, characterized in that The component is a power module (LM) of a power electronics device.

10. Device (VG) according to claim 8, characterized in that The generating device (EE) generates the at least one first high-frequency image (HFA1) based on a mathematical method for image reconstruction.

11. Device (VG) according to claim 8, characterized in that The high-frequency antenna arrangement (HFAO) is designed such that the component (BT) is scanned in rows and columns in the case of two-dimensional scanning, wherein each antenna is used or acts alternately as a transmitter and a receiver, wherein the duration of the use / acting as a receiver is a multiple of the duration of the use / acting as a transmitter in relation to the number of antennas in the high-frequency antenna arrangement (HFAO).

12. Device (VG) according to claim 11, characterized in that The high-frequency antenna arrangement (HFAO) is designed as an antenna array or as a T-shaped arrangement.

13. Device (VG) according to any one of claims 8 to 12, characterized in that The functional unit (FE) formed by the ultrasonic signal device (USSE) and the high-frequency antenna device (HFAO) and the comparison device (VGE) are designed such that In the case of a two-dimensional scan, the position and extent of damage or delamination on the component (BT) are explained using a difference image representing changes in the high-frequency images (HFA1, HFA2).

14. Device (VG) according to claim 13, characterized in that The functional unit (FE) formed by the ultrasonic signal device (USSE) and the high-frequency antenna device (HFAO) and the comparison device (VGE) are designed such that Damage or delamination on the component (BT) is indicated by the maximum amplitude in the difference image.

15. Device (VG) according to any one of claims 8 to 12, characterized in that The ultrasonic signaling device (USSE) comprises at least one ultrasonic oscillator.

16. Device (VG) according to claim 15, characterized in that The sonotrode is designed in such a way that, if the component (BT) is a power module (LM), the ultrasonic signal radiation is radiated directly in the base region of the power module (LM).

17. A power electronic device (LEG), Features The device (VG) according to any one of claims 8 to 16, which performs the method according to any one of claims 1 to 7.

18. The power electronic device (LEG) according to claim 17, characterized in that The power electronics device (LEG) is a converter.

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