Power semiconductor device fault defect detection device and detection method

Abstract

The invention discloses a method for detecting faults and defects of a power semiconductor device. The method comprises the following steps: providing periodic square wave detection voltage for a to-be-detected power semiconductor device; capturing infrared thermograms of the to-be-tested power semiconductor device in different periods; analyzing and processing the infrared thermogram and obtaining an actual heating image; determining an abnormal heating image based on the actual heating image; and determining a fault defect position of the to-be-detected power semiconductor device based on the abnormal heating image. The invention further discloses a device for detecting the fault defects of the power semiconductor device. The power semiconductor device comprises but not limited to an IGBT, an MOSFET, a JFET, a BJT, an SCR, an ASIC and the like. The method has the beneficial effects that by setting the periodic square wave detection voltage, the temperature difference of the fault defect with small abnormal heating can be amplified, the detection accuracy is improved, and the infrared thermogram is captured and analyzed and calculated so as to accurately position the fault defect position of the power semiconductor device to be detected.

Description

Technical Field

[0001] The present invention relates to the technical field of power semiconductor device fault defect detection, and in particular to a power semiconductor device fault defect detection device and a detection method. Background Art

[0002] like Figure 1 As shown, in the prior art, after the PCB board under test is powered on, an infrared thermal imager is used to capture images of temperature changes at various points on the surface of the PCB board under test and store them in a computer. The computer compares the images captured by the infrared thermal imager with the infrared thermal images of the normally functioning PCB board collected in advance to determine the fault location of the defective device in the PCB board under test, which is then displayed to the tester on a display for visual analysis. However, this test method cannot avoid external interference, and it is easy to cause a problem where a small abnormal heating defect is submerged in the heating difference between boards and external interference, which results in the inability to detect the defect. Summary of the invention

[0003] In order to solve the above problems, an object of the present invention is to provide a detection device and a detection method for fault defects of power semiconductor devices.

[0004] The present invention provides a method for detecting a fault defect of a power semiconductor device, the method comprising:

[0005] Providing a periodic square wave detection voltage to the power semiconductor device to be tested;

[0006] Capturing infrared thermal images of the power semiconductor device to be tested in different cycles;

[0007] Analyzing and processing the infrared thermal image to obtain an actual heating image;

[0008] determining an abnormal fever image based on the actual fever image;

[0009] The fault defect position of the power semiconductor device to be tested is determined based on the abnormal heating image.

[0010] As a further improvement of the present invention, the capturing of infrared thermal images of the power semiconductor device to be tested in different periods includes:

[0011] In the nth cycle of the periodic square wave detection voltage, the first infrared thermal image P when the voltage changes from a high level to a low level is captured respectively. nt1 And the second infrared thermal image P when the voltage changes from low level to high level nt2 .

[0012] As a further improvement of the present invention, when the voltage changes from a high level to a low level, an infrared thermal image or multiple infrared thermal images are captured as the first infrared thermal image P nt1 , when the voltage changes from a low level to a high level, an infrared thermal image or multiple infrared thermal images are captured as the second infrared thermal image P nt2 .

[0013] As a further improvement of the present invention, when the voltage changes from a high level to a low level, a plurality of infrared thermal images are captured as the first infrared thermal image P nt1 , and capturing multiple infrared thermal images as the second infrared thermal image P when the voltage changes from a low level to a high level nt2 include:

[0014] Determining a weight k of each infrared thermal image in the plurality of infrared thermal images;

[0015] Determine the first infrared thermal image P according to each infrared thermal image and the corresponding weight nt1 And the second infrared thermal image P nt2 ,

[0016] P nt1 =k1·P nt11 +k2·P nt12 +…+k j ·P nt1j +…+k m ·P nt1m ,

[0017] P nt2 =k1·P nt21 +k2·P nt22 +…+k j ·P nt2j +…+k m ·P nt2m ,

[0018] Where m is the number of infrared thermal images, k is j is the weight of the jth infrared thermal image, 1≤j≤m, and the total weight of multiple infrared thermal images is 100%, that is, k1+k2+…+k j +…+k m =100%.

[0019] As a further improvement of the present invention, the step of analyzing and processing the infrared thermal image to obtain an actual heating image includes:

[0020] The first infrared thermal image P in different periods nt1 And the second infrared thermal image P nt2 Perform noise reduction processing;

[0021] Determine an intensity value x, and based on the intensity value x, nt1 And the second infrared thermal image P nt2 The clarity of the details is enhanced to obtain the enhanced first infrared thermal image And the enhanced second infrared thermal image

[0022] Calculate the thermal blur image P of the power semiconductor device under test in the nth cycle n :

[0023]

[0024] The actual heating image P of the power semiconductor device to be tested is obtained by superimposing the heating fuzzy images in different periods. sum :

[0025] P sum =P1+P2+…+P i +…+P n ,

[0026] Among them, P i represents the thermal blurred image of the i-th period, 1≤i≤n.

[0027] As a further improvement of the present invention, the step of analyzing and processing the infrared thermal image to obtain an actual heating image includes:

[0028] The first infrared thermal image P in different periods nt1 And the second infrared thermal image P nt2 Perform noise reduction processing;

[0029] Determine an intensity value x, and based on the intensity value x, nt1 And the second infrared thermal image P nt2 The clarity of the details is enhanced to obtain the enhanced first infrared thermal image And the enhanced second infrared thermal image

[0030] The enhanced first infrared thermal images in different periods and the enhanced second infrared thermal image Superimpose them respectively to obtain the first heating blurred image P t1 and the second thermally blurred image P t2 ,

[0031]

[0032] Calculate the actual heating image P sum :

[0033] P sum =P t1 -P t2 ,

[0034] in, and They respectively represent the enhanced first infrared thermal image and the enhanced second infrared thermal image in the i-th period.

[0035] As a further improvement of the present invention, the determining of the abnormal fever image based on the actual fever image includes:

[0036] Determine the operating state of the power semiconductor device during the detection process:

[0037] If the power semiconductor device is turned on during the detection process, the abnormal heating image P is:

[0038] P=P sum -P0,

[0039] If the power semiconductor device remains in the off state during the detection process, the abnormal heating image P is:

[0040] P=P sum ,

[0041] Among them, P0 is a pre-stored standard heating image of a normal power semiconductor device.

[0042] As a further improvement of the present invention, the step of determining the fault defect position of the power semiconductor device to be tested based on the abnormal heating image includes:

[0043] Capturing a physical image of the power semiconductor device to be tested;

[0044] The abnormal heating image is overlaid on the physical image for simultaneous display to determine the fault defect location of the power semiconductor device to be tested.

[0045] The present invention also provides a detection device for a fault defect of a power semiconductor device, the detection device comprising:

[0046] A power supply module, used for providing a periodic square wave detection voltage to the power semiconductor device to be tested;

[0047] An image acquisition module, arranged above the power semiconductor device to be tested, and used for capturing infrared thermal images of the power semiconductor device to be tested in different periods;

[0048] An analysis and processing module is connected to the image acquisition module for receiving, analyzing and processing the infrared thermal image to obtain an abnormal heating image for determining the fault defect location of the power semiconductor device to be tested;

[0049] A control module is connected to the power supply module and the image acquisition module for controlling the detection process.

[0050] As a further improvement of the present invention, the image acquisition module is used to capture the first infrared thermal image P when the voltage changes from a high level to a low level in the nth period of the periodic square wave detection voltage. nt1 And the second infrared thermal image P when the voltage changes from low level to high level nt2 .

[0051] As a further improvement of the present invention, the image acquisition module is used to capture an infrared thermal image or multiple infrared thermal images as the first infrared thermal image P when the voltage changes from a high level to a low level. nt1 , when the voltage changes from a low level to a high level, an infrared thermal image or multiple infrared thermal images are captured as the second infrared thermal image P nt2 .

[0052] As a further improvement of the present invention, the analysis and processing module is used to determine the weight k of each infrared thermal image in the plurality of infrared thermal images; and determine the first infrared thermal image P according to each infrared thermal image and the corresponding weight. nt1 And the second infrared thermal image P nt2 ,

[0053] P nt1 =k1·P nt11 +k2·P nt12 +…+k j ·P nt1j +…+k m ·P nt1m ,

[0054] P nt2 =k1·P nt21 +k2·P nt22 +…+k j ·P nt2j +…+k m ·P nt2m ,

[0055] Where m is the number of infrared thermal images, k is j is the weight of the jth infrared thermal image, 1≤j≤m, and the total weight of multiple infrared thermal images is 100%, that is, k1+k2+…+k j +…+k m =100%.

[0056] As a further improvement of the present invention, the analysis and processing module is used to analyze the first infrared thermal image P in different periods. nt1 And the second infrared thermal image P nt2 Perform noise reduction processing;

[0057] Determine an intensity value x, and based on the intensity value x, nt1 And the second infrared thermal image P nt2 The clarity of the details is enhanced to obtain the enhanced first infrared thermal image And the enhanced second infrared thermal image

[0058] Calculate the thermal blur image P of the power semiconductor device under test in the nth cycle n :

[0059]

[0060] The actual heating image P of the power semiconductor device to be tested is obtained by superimposing the heating fuzzy images in different periods. sum :

[0061] P sum =P1+P2+…+P i +…+P n ,

[0062] Among them, P i represents the thermal blurred image of the i-th period, 1≤i≤n.

[0063] As a further improvement of the present invention, the analysis and processing module is used to analyze the first infrared thermal image P in different periods. nt1 And the second infrared thermal image P nt2 Perform noise reduction processing;

[0064] Determine an intensity value x, and based on the intensity value x, nt1 And the second infrared thermal image P nt2 The clarity of the details is enhanced to obtain the enhanced first infrared thermal image And the enhanced second infrared thermal image

[0065] The enhanced first infrared thermal images in different periods and the enhanced second infrared thermal image Superimpose them respectively to obtain the first heating blurred image P t1 and the second thermally blurred image P t2 ,

[0066]

[0067] Calculate the actual heating image P sum :

[0068] P sum =P t1 -P t2 ,

[0069] in, and They respectively represent the enhanced first infrared thermal image and the enhanced second infrared thermal image in the i-th period.

[0070] As a further improvement of the present invention, the analysis and processing module is used to determine the operating state of the power semiconductor device during the detection process:

[0071] If the power semiconductor device is turned on during the detection process, the abnormal heating image P is:

[0072] P=P sum -P0,

[0073] If the power semiconductor device remains in the off state during the detection process, the abnormal heating image P is:

[0074] P=P sum ,

[0075] Among them, P0 is a pre-stored standard heating image of a normal power semiconductor device.

[0076] As a further improvement of the present invention, the device also includes an imaging module and a display, the imaging module is used to capture the physical image of the power semiconductor device to be tested; the display is used to overlay the abnormal heating image on the physical image for synchronous display, so as to determine the fault defect location of the power semiconductor device to be tested.

[0077] As a further improvement of the present invention, the device also includes a dynamic positioning module, which is fixedly connected to the image acquisition module, executes the action instructions of the control module, and controls the position change of the image acquisition module.

[0078] The beneficial effects of the present invention are as follows: a periodic square wave detection voltage is provided to the power semiconductor device to be tested, which not only conforms to the heating characteristics of the semiconductor device with a fault defect, but also can amplify the temperature difference of the fault defect with a smaller heating abnormality, thereby improving the detection accuracy. At the same time, by capturing the infrared thermal image of the periodic heating of the power semiconductor device to be tested and analyzing and calculating it, a clear abnormal heating image can be obtained to accurately locate the position of the fault defect of the power semiconductor device to be tested. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor.

[0080] Figure 1 A detection device for power semiconductor device fault defects in the prior art;

[0081] Figure 2 A flow chart of a method for detecting a fault defect of a power semiconductor device according to an exemplary embodiment of the present invention;

[0082] Figure 3 A schematic diagram of capturing an infrared thermal image per cycle in a method for detecting a fault defect of a power semiconductor device according to an exemplary embodiment of the present invention;

[0083] Figure 4 A schematic diagram of capturing two infrared thermal images per cycle in a method for detecting a fault defect of a power semiconductor device according to an exemplary embodiment of the present invention;

[0084] Figure 5 The present invention is a schematic structural diagram of a device for detecting a fault defect of a power semiconductor device according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0085] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0086] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0087] In addition, in the description of the present invention, the terms used are only for illustrative purposes and are not intended to limit the scope of the present invention. The terms "include" and / or "comprise" are used to specify the existence of the elements, steps, operations and / or components, but do not exclude the existence or addition of one or more other elements, steps, operations and / or components. The terms "first", "second" and the like may be used to describe various elements, do not represent the order, and do not limit these elements. In addition, in the description of the present invention, unless otherwise specified, the meaning of "multiple" is two and more than two. These terms are only used to distinguish one element from another element. In conjunction with the following drawings, these and / or other aspects become apparent, and it is easier for a person of ordinary skill in the art to understand the description of the embodiments of the present invention. The accompanying drawings are used to describe the embodiments of the present invention for illustrative purposes only. Those skilled in the art will easily recognize from the following description that, without departing from the principles of the present invention, alternative embodiments of the structures and methods shown in the present invention can be adopted.

[0088] like Figure 2 As shown, a method for detecting a fault defect of a power semiconductor device according to an embodiment of the present invention comprises:

[0089] A periodic square wave detection voltage is provided to the power semiconductor device to be tested. The square wave has the characteristic of instantaneous switching between high level and low level. Its fast rising and falling edges meet the heating characteristics of semiconductor devices with fault defects. Setting the square wave to be periodic can ensure that the acquired infrared thermal images are under the same external environmental conditions, thereby improving the detection accuracy.

[0090] Among them, when providing a periodic square wave detection voltage to the power semiconductor device to be tested, the voltage value can be changed according to the actual detection situation to obtain a clearer abnormal heating image, or the power supply module can be designed as a gradually boosting mode to gradually obtain a clearer abnormal heating image. This application does not make any specific limitations on this.

[0091] For example, when the contrast of the abnormal heating image is low, the inspector can issue a boost instruction, and the control module controls the power supply module to provide a periodic square wave detection voltage with a larger voltage amplitude to the power semiconductor device to be tested, thereby increasing the temperature difference between the rising edge and the falling edge of the power semiconductor device to be tested, and obtaining an abnormal heating image with obvious color difference. When the power supply module is in a gradual boost mode, as the voltage amplitude of the periodic square wave detection voltage becomes larger and larger, the temperature difference between the rising edge and the falling edge of the power semiconductor device to be tested will also become larger and larger, and an abnormal heating image with increasingly obvious color difference will be obtained. Among them, the maximum value of the periodic square wave detection voltage should be less than the rated voltage of the power semiconductor device to be tested.

[0092] Capturing infrared thermal images of the power semiconductor device to be tested in different cycles.

[0093] When capturing infrared thermal images, the position and direction of the captured infrared thermal images can be adjusted according to the actual detection situation and the location of the fault defect. For example, when the detection finds that the location of the fault defect is relatively concentrated and it is impossible to determine the specific damaged component, the position of the equipment can be adjusted to capture only the infrared thermal image within the area to magnify the fault area and improve the clarity of the image of the specific damaged component location, so as to more accurately locate and identify the specific damaged component.

[0094] Furthermore, capturing infrared thermal images of the power semiconductor device to be tested in different periods includes:

[0095] In the nth cycle of the periodic square wave detection voltage, the first infrared thermal image P when the voltage changes from a high level to a low level is captured respectively. nt1 And the second infrared thermal image P when the voltage changes from low level to high level nt2 .

[0096] Further, such as Figure 3 , Figure 4 As shown, when the voltage changes from a high level to a low level, an infrared thermal image or multiple infrared thermal images are captured as the first infrared thermal image P nt1 , when the voltage changes from a low level to a high level, an infrared thermal image or multiple infrared thermal images are captured as the second infrared thermal image P nt2 .

[0097] When only one infrared thermal image is captured, the infrared thermal image is the first infrared thermal image or the second infrared thermal image; when multiple infrared thermal images are captured, it is preferred to characterize infrared thermal images in different states in a weighted manner to obtain the first infrared thermal image or the second infrared thermal image.

[0098] Furthermore, when the voltage changes from a high level to a low level, a plurality of infrared thermal images are captured as the first infrared thermal image P nt1 , and capturing multiple infrared thermal images as the second infrared thermal image P when the voltage changes from a low level to a high level nt2 include:

[0099] Determining a weight k of each infrared thermal image in the plurality of infrared thermal images;

[0100] Determine the first infrared thermal image P according to each infrared thermal image and the corresponding weight nt1 And the second infrared thermal image P nt2 ,

[0101] P nt1 =k1·Pnt11 +k2·P nt12 +…+k j ·P nt1j +…+k m ·P nt1m ,

[0102] P nt2 =k1·P nt21 +k2·P nt22 +…+k j ·P nt2j +…+k m ·P nt2m ,

[0103] Where m is the number of infrared thermal images, k is j is the weight of the jth infrared thermal image, 1≤j≤m, and the total weight of multiple infrared thermal images is 100%, that is, k1+k2+…+k j +…+k m =100%.

[0104] By setting weights for infrared thermal images captured in different states within the same cycle, it is possible to distinguish the impact of the states at different time periods within the cycle on the temperature change of the power semiconductor device to be tested, reduce the accidental deviation caused by capturing only one infrared thermal image, and improve detection accuracy.

[0105] Take the example of capturing four infrared thermal images when the voltage changes from a high level to a low level: In these four infrared thermal images, the first infrared thermal image P nt11 Corresponding to the current voltage being at a high level, the second infrared thermal image P nt12 Corresponding to the current voltage being in the transition stage from high level to low level, the third infrared thermal image P nt13 And the fourth infrared thermal image P nt14 Corresponding to the current voltage being at a low level, at this time, the first infrared thermal image P nt1 for:

[0106] P nt1 =k1·P nt11 +k2·P nt12 +k3·P nt13 +k4·P nt14 , (k1+k2+k3+k4=100%).

[0107] Preferably, k1=20%, k2=50%, k3=15%, k4=15%, so as to highlight the temperature change of the power semiconductor device to be tested during the transition of the voltage from a high level to a low level. The above mathematical operations are all performed on the pixel values ​​of the image.

[0108] The above-mentioned infrared thermal image captured when the voltage changes from a high level to a low level is a schematic example. The above-mentioned method can also be used to capture the infrared thermal image when the voltage changes from a low level to a high level, which will not be repeated here. It is understandable that other numbers of infrared thermal images can also be captured, such as two infrared thermal images, three infrared thermal images, four infrared thermal images, or more first infrared thermal images. The present application does not limit the number of captured infrared thermal images and how to set the weights of multiple infrared thermal images. The specific weights can be adaptively designed according to the number of captured infrared thermal images and the stage at which the levels of each infrared thermal image are located.

[0109] The infrared thermal image is analyzed and processed to obtain an actual heating image.

[0110] Furthermore, the analyzing and processing the infrared thermal image to obtain the actual heating image includes:

[0111] The first infrared thermal image P in different periods nt1 And the second infrared thermal image P nt2 Perform noise reduction processing;

[0112] Among them, noise reduction processing is generally divided into a preprocessing stage, a noise analysis stage, a noise reduction processing stage, and a post-processing stage. Preprocessing stage: grayscale and normalize the infrared thermal image. Convert the infrared thermal image into a grayscale image so that the subsequent noise reduction algorithm can focus more on processing the pixel values ​​of the image, so as to more effectively reduce noise and retain important temperature information. Normalization can ensure that the pixel values ​​are within a uniform range, which is convenient for subsequent processing and analysis. Noise analysis stage: analyze the type of noise in the infrared thermal image, evaluate the intensity, distribution, frequency and other characteristics of the noise, and select a suitable noise reduction method. Noise reduction processing stage: select a noise reduction method for noise reduction based on the analysis results, such as using filtering methods such as median filtering, average neighborhood method (mean filtering), wavelet transform combined with mean filtering, and non-local mean method. Post-processing stage: perform detail enhancement and / or dynamic range adjustment on the infrared thermal image after noise reduction to further improve the quality of the infrared thermal image.

[0113] Determine an intensity value x, and based on the intensity value x, nt1 And the second infrared thermal image P nt2 The clarity of the details is enhanced to obtain the enhanced first infrared thermal image And the enhanced second infrared thermal image

[0114] Preferably, the value range of the intensity value x is x≥0.1. The intensity values ​​of the first infrared thermal image and the second infrared thermal image in different periods are the same, so as to ensure that the infrared thermal images obtained in different periods are under the same external environment conditions.

[0115] Setting a reasonable intensity value can amplify the heating difference between the fault defect and the background in the infrared thermal image, so as to detect fault defects with smaller heating anomalies and further improve the detection accuracy. When x>1, the high-brightness area in the image will become brighter, while the low-brightness area will become relatively darker, which helps to enhance the bright details in the image. When 0.1≤x<1, the low-brightness area in the image will become brighter, while the high-brightness area will become relatively darker, which helps to enhance the dark details in the image and make the image look softer as a whole. When x=1, the image remains unchanged. For example, when the contrast of the abnormal heating image is low or it is impossible to determine whether there is a fault defect at the location due to the small heating anomaly, the intensity value can be appropriately increased to improve the detection sensitivity and enhance the clarity at the location where the small temperature difference is located. The intensity value of the infrared thermal image data can be determined based on the actual product and the fault defect of the product, and this application does not limit this.

[0116] Calculate the thermal blur image P of the power semiconductor device under test in the nth cycle n :

[0117]

[0118] Using the enhanced first infrared thermal image The pixel value of the enhanced second infrared image is subtracted from the pixel value of the second infrared image The pixel values ​​of the power semiconductor device to be tested can be used to obtain the temperature difference matrix of each pixel point in the same period. If the power semiconductor device to be tested has abnormal heating, the value after subtraction will highlight the temperature difference at the abnormal position.

[0119] The pixel values ​​of the heating blurred images in different periods are superimposed to obtain the actual heating image P of the power semiconductor device to be tested. sum :

[0120] P sum =P1+P2+…+P i +…+P n ,

[0121] Among them, P i represents the thermal blurred image of the i-th period, 1≤i≤n.

[0122] Furthermore, the analyzing and processing the infrared thermal image to obtain the actual heating image includes:

[0123] The first infrared thermal image P in different periods nt1 And the second infrared thermal image P nt2 Perform noise reduction processing;

[0124] Determine an intensity value x, and based on the intensity value x, nt1 And the second infrared thermal image P nt2 The clarity of the details is enhanced to obtain the enhanced first infrared thermal image And the enhanced second infrared thermal image The setting of the intensity value x is the same as in the above embodiment and will not be repeated here.

[0125] The enhanced first infrared thermal images in different periods are respectively The pixel value and the enhanced second infrared thermal image The pixel values ​​of the pixels are superimposed to obtain the first heating blurred image P t1 and the second thermally blurred image P t2 ,

[0126]

[0127] Calculate the actual heating image P sum :

[0128] P sum =P t1 -P t2 ,

[0129] in, and They respectively represent the enhanced first infrared thermal image and the enhanced second infrared thermal image in the i-th period.

[0130] An abnormal fever image is determined based on the actual fever image.

[0131] Further, determining the abnormal fever image based on the actual fever image includes:

[0132] To determine the operating status of the power semiconductor device during the detection process, the power semiconductor device will be powered on and off in a cycle. During the detection process, when the power semiconductor device is in the off state, the actual heating image only shows the heat generated by the power semiconductor device to be tested under the action of the periodic square wave detection voltage. When the power semiconductor device is in the on state, the actual heating image shows the heat generated by the power semiconductor device to be tested under the dual action of the periodic square wave detection voltage and the power-on voltage.

[0133] If the power semiconductor device is turned on during the detection process, that is, the actual heating image includes the heat generated by the power semiconductor device under the power-on voltage, then the abnormal heating image should be the actual heating image minus the standard heating image of the normal power semiconductor device, so as to extract the heat generated by the power semiconductor device under the periodic square wave detection voltage and amplify the temperature difference at the fault defect location, that is, the abnormal heating image P is the actual heating image P sum The pixel value of the standard fever image P0 is subtracted from the pixel value of the standard fever image P0: P = P sum -P0, where P0 is a pre-stored standard heating image of a normal power semiconductor device;

[0134] If the power semiconductor device is kept in the off state during the detection process, that is, the actual heating image is only the heating generated by the power semiconductor device under the action of the periodic square wave detection voltage, then the actual heating image is the abnormal heating image, that is, the abnormal heating image P is: P = P sum .

[0135] The fault defect position of the power semiconductor device to be tested is determined based on the abnormal heating image.

[0136] Further, determining the fault defect position of the power semiconductor device to be tested based on the abnormal heating image includes:

[0137] Capturing a physical image of the power semiconductor device to be tested, wherein the physical image matches the abnormal heating image, and the physical image and the abnormal heating image completely overlap, is conducive to intuitively visually locating the fault defect position of the power semiconductor device to be tested.

[0138] Preferably, a physical image of the power semiconductor device to be tested is captured before the infrared thermal image is captured. When the position and direction of capturing the infrared thermal image change, a new physical image should be captured at this position and saved to avoid the problem that the physical image cannot match the abnormal heating image.

[0139] The abnormal heating image is overlaid on the physical image for simultaneous display to determine the fault defect location of the power semiconductor device to be tested.

[0140] like Figure 5 As shown, the present invention also provides a detection device for a fault defect of a power semiconductor device, the detection device comprising:

[0141] A power supply module, used for providing a periodic square wave detection voltage to the power semiconductor device to be tested;

[0142] An image acquisition module, arranged above the power semiconductor device to be tested, and used for capturing infrared thermal images of the power semiconductor device to be tested in different periods;

[0143] An analysis and processing module is connected to the image acquisition module for receiving, analyzing and processing the infrared thermal image to obtain an abnormal heating image for determining the fault defect location of the power semiconductor device to be tested;

[0144] A control module is connected to the power supply module and the image acquisition module for controlling the detection process.

[0145] The power supply module is set to provide a periodic square wave detection voltage to the power semiconductor device under test, which not only conforms to the heating characteristics of the semiconductor device with a fault defect, but also can amplify the temperature difference of the fault defect with a smaller heating abnormality, thereby improving the detection accuracy. At the same time, an image acquisition module is set to capture the infrared thermal image of the periodic heating of the power semiconductor device under test and analyze and calculate it, so as to obtain a clear abnormal heating image to accurately locate the fault defect position of the power semiconductor device under test.

[0146] Preferably, the detection device is further provided with a thermal imaging test box, in which the image acquisition module and the power semiconductor device to be tested are placed, which can not only isolate external thermal noise, but also reduce heat reflection in the box, so as to further reduce the influence of external interference on the detection results. Preferably, a monitoring system is also provided inside the thermal imaging test box, and the detection personnel can observe the monitoring system to view the detection situation in the thermal imaging test box in real time.

[0147] Preferably, the image acquisition module uses an infrared thermal imager with a wavelength range of 8μm-14μm. Infrared cameras in this band have high sensitivity and can capture tiny temperature differences, further improving the accuracy of detection.

[0148] Preferably, the detection device is further provided with an EUT fixture to fix the power semiconductor device to be tested.

[0149] In one embodiment, the image acquisition module is used to capture the first infrared thermal image P when the voltage changes from a high level to a low level in the nth period of the periodic square wave detection voltage. nt1 And the second infrared thermal image P when the voltage changes from low level to high level nt2 .

[0150] In one embodiment, the image acquisition module is used to capture an infrared thermal image or multiple infrared thermal images as the first infrared thermal image P when the voltage changes from a high level to a low level. nt1 , when the voltage changes from a low level to a high level, an infrared thermal image or multiple infrared thermal images are captured as the second infrared thermal image P nt2 .

[0151] In one embodiment, the analysis and processing module is used to determine the weight k of each infrared thermal image in the plurality of infrared thermal images; and determine the first infrared thermal image P according to each infrared thermal image and the corresponding weight. nt1 And the second infrared thermal image P nt2 ,

[0152] P nt1 =k1·P nt11 +k2·P nt12 +…+k j ·P nt1j +…+k m ·P nt1m ,

[0153] P nt2 =k1·P nt21 +k2·P nt22 +…+k j ·P nt2j +…+k m ·P nt2m ,

[0154] Where m is the number of infrared thermal images, k is j is the weight of the jth infrared thermal image, 1≤j≤m, and the total weight of multiple infrared thermal images is 100%, that is, k1+k2+…+k j +…+k m =100%.

[0155] In one embodiment, the analysis and processing module is used to analyze the first infrared thermal image P in different periods. nt1 And the second infrared thermal image P nt2 Perform noise reduction processing;

[0156] Determine an intensity value x, and based on the intensity value x, nt1 And the second infrared thermal image P nt2 The clarity of the details is enhanced to obtain the enhanced first infrared thermal image And the enhanced second infrared thermal image

[0157] Calculate the thermal blur image P of the power semiconductor device under test in the nth cycle n :

[0158]

[0159] The actual heating image P of the power semiconductor device to be tested is obtained by superimposing the heating fuzzy images in different periods. sum :

[0160] P sum =P1+P2+…+P i +…+P n ,

[0161] Among them, P i represents the thermal blurred image of the i-th period, 1≤i≤n.

[0162] In one embodiment, the analysis and processing module is used to analyze the first infrared thermal image P in different periods. nt1 And the second infrared thermal image P nt2 Perform noise reduction processing;

[0163] Determine an intensity value x, and based on the intensity value x, nt1 And the second infrared thermal image P nt2 The clarity of the details is enhanced to obtain the enhanced first infrared thermal image And the enhanced second infrared thermal image

[0164] The enhanced first infrared thermal images in different periods and the enhanced second infrared thermal image Superimpose them respectively to obtain the first heating blurred image P t1 and the second thermally blurred image P t2 ,

[0165]

[0166] Calculate the actual heating image P sum :

[0167] P sum =P t1 -P t2 ,

[0168] in, and They respectively represent the enhanced first infrared thermal image and the enhanced second infrared thermal image in the i-th period.

[0169] In one embodiment, the analysis and processing module is used to judge the operating state of the power semiconductor device during the detection process to determine whether the captured infrared thermal image contains the heat generated by the power semiconductor device under the power-on voltage.

[0170] If the power semiconductor device is turned on during the detection process, the abnormal heating image P is:

[0171] P=Psum -P0,

[0172] If the power semiconductor device remains in the off state during the detection process, the abnormal heating image P is:

[0173] P=P sum ,

[0174] Among them, P0 is a pre-stored standard heating image of a normal power semiconductor device.

[0175] When using the analysis and processing module for judgment, the potential value can be pre-set to 0, and before the detection begins, the potential value is reset to ensure that it is 0. During the operation of the detection device, if the power semiconductor device to be tested is not powered on, the potential value is 0, and the corresponding processing method is selected; if the analysis and processing module detects that the power semiconductor device to be tested is powered on, the potential value is set to 1, and the corresponding processing method is selected.

[0176] In one embodiment, the device also includes an imaging module and a display, wherein the imaging module is used to capture a physical image of the power semiconductor device to be tested; and the display is used to overlay the abnormal heating image on the physical image for synchronous display to determine the fault defect location of the power semiconductor device to be tested.

[0177] The imaging module and the image acquisition module are arranged in parallel, and under the control of the control module, a physical image of the power semiconductor device to be tested matching the infrared thermal image is captured, and the physical image is transmitted to the analysis and processing module.

[0178] Setting the imaging module and the image acquisition module in parallel can ensure the consistency of the phases of the two, so as to avoid the problem that the physical image captured by the imaging module cannot match the infrared thermal image captured by the image acquisition module. Setting a display can receive the test data returned by the analysis and processing module, which is conducive to the inspection personnel to query the historical test data through the display. Moreover, the final result is directly displayed on the display, which can quickly and intuitively determine the fault or defect location in the power semiconductor device to be tested.

[0179] Preferably, the imaging module uses a visible light camera.

[0180] In one embodiment, the device further comprises a dynamic positioning module, which is fixedly connected to the image acquisition module and executes the action instructions of the control module to control the position change of the image acquisition module.

[0181] The dynamic positioning module can drive the image acquisition module and the imaging module to move in space, for example, forward and backward, left and right, up and down, or even in any direction, thereby realizing detection of any area and any height of the power semiconductor device to be tested, so as to more accurately locate and identify the specific damaged components in the power semiconductor device to be tested.

[0182] Preferably, the dynamic positioning module is also fixedly connected to the imaging module, executes the action instructions of the control module, and controls the imaging module to complete the same position transformation as the image acquisition module.

[0183] Preferably, the dynamic positioning module is a manipulator, and the image acquisition module and the imaging module are fixed on the manipulator by a clamp to facilitate disassembly, assembly and maintenance.

[0184] It is understandable that the power semiconductor devices to be tested mentioned above include but are not limited to IGBT, MOSFET, JFET, BJT, SCR, MSIC, RFIC, PIC and ASIC, etc., and this application does not limit this.

[0185] In the description provided herein, a large number of specific details are described. However, it is understood that embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0186] Furthermore, persons of ordinary skill in the art will appreciate that although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features from different embodiments is meant to be within the scope of the present invention and to form different embodiments.

[0187] It will be appreciated by those skilled in the art that, although the present invention has been described with reference to exemplary embodiments, various changes may be made and its elements may be replaced with equivalents without departing from the scope of the present invention. In addition, many modifications may be made to adapt specific situations or materials to the teachings of the present invention without departing from the essential scope of the present invention.

Claims

1. A method for detecting a fault defect of a power semiconductor device, characterized in that: The method comprises: Providing a periodic square wave detection voltage to the power semiconductor device to be tested; Capturing infrared thermal images of the power semiconductor device to be tested in different cycles; Analyzing and processing the infrared thermal image to obtain an actual heating image; determining an abnormal fever image based on the actual fever image; The fault defect position of the power semiconductor device to be tested is determined based on the abnormal heating image.

2. The detection method according to claim 1, characterized in that The capturing of infrared thermal images of the power semiconductor device to be tested in different cycles comprises: In the nth cycle of the periodic square wave detection voltage, the first infrared thermal image P when the voltage changes from a high level to a low level is captured respectively. nt1 And the second infrared thermal image P when the voltage changes from low level to high level nt2 .

3. The detection method according to claim 2, characterized in that When the voltage changes from a high level to a low level, an infrared thermal image or multiple infrared thermal images are captured as the first infrared thermal image P nt1 , when the voltage changes from a low level to a high level, an infrared thermal image or multiple infrared thermal images are captured as the second infrared thermal image P nt2 .

4. The detection method according to claim 3, characterized in that The method captures a plurality of infrared thermal images as the first infrared thermal image P when the voltage changes from a high level to a low level. nt1 , and capturing multiple infrared thermal images as the second infrared thermal image P when the voltage changes from a low level to a high level nt2 include: Determining a weight k of each infrared thermal image in the plurality of infrared thermal images; Determine the first infrared thermal image P according to each infrared thermal image and the corresponding weight nt1 And the second infrared thermal image P nt2 , P nt1 =k1 P nt11 +k2 P nt12 +…+k j ·P nt1j +…+k m ·P nt1m , P nt2 =k1 P nt21 +k2 P nt22 +…+k j ·P nt2j +…+k m ·P nt2m , Where m is the number of infrared thermal images, k is j is the weight of the jth infrared thermal image, 1≤j≤m, and the total weight of multiple infrared thermal images is 100%, that is, k1+k2+…+k j +…+k m =100%.

5. The detection method according to claim 4, characterized in that: The analyzing and processing the infrared thermal image to obtain the actual heating image comprises: The first infrared thermal image P in different periods nt1 And the second infrared thermal image P nt2 Perform noise reduction processing; Determine an intensity value x, and based on the intensity value x, nt1 And the second infrared thermal image P nt2 The clarity of the details is enhanced to obtain the enhanced first infrared thermal image And the enhanced second infrared thermal image Calculate the thermal blur image P of the power semiconductor device under test in the nth cycle n : The actual heating image P of the power semiconductor device to be tested is obtained by superimposing the heating fuzzy images in different periods. sum : P sum =P1+P2+…+P i +…+P n , Among them, P i represents the thermal blurred image of the i-th period, 1≤i≤n.

6. The detection method according to claim 4, characterized in that: The analyzing and processing the infrared thermal image to obtain the actual heating image comprises: The first infrared thermal image P in different periods nt1 And the second infrared thermal image P nt2 Perform noise reduction processing; Determine an intensity value x, and based on the intensity value x, nt1 And the second infrared thermal image P nt2 The clarity of the details is enhanced to obtain the enhanced first infrared thermal image And the enhanced second infrared thermal image The enhanced first infrared thermal images in different periods and the enhanced second infrared thermal image Superimpose them respectively to obtain the first heating blurred image P t1 and the second thermally blurred image P t2 , Calculate the actual heating image P sum : P sum =P t1 -P t2 , in, and They respectively represent the enhanced first infrared thermal image and the enhanced second infrared thermal image in the i-th period.

7. The detection method according to claim 5 or 6, characterized in that: The determining of the abnormal fever image based on the actual fever image comprises: Determine the operating state of the power semiconductor device during the detection process: If the power semiconductor device is turned on during the detection process, the abnormal heating image P is: P=P sum -P0, If the power semiconductor device remains in the off state during the detection process, the abnormal heating image P is: P=P sum , Among them, P0 is a pre-stored standard heating image of a normal power semiconductor device.

8. The detection method according to claim 1, characterized in that The determining the fault defect position of the power semiconductor device to be tested based on the abnormal heating image comprises: Capturing a physical image of the power semiconductor device to be tested; The abnormal heating image is overlaid on the physical image for simultaneous display to determine the fault defect location of the power semiconductor device to be tested.

9. A detection device using the method for detecting a power semiconductor device fault defect according to any one of claims 1 to 8, characterized in that: The detection device comprises: A power supply module, used for providing a periodic square wave detection voltage to the power semiconductor device to be tested; An image acquisition module, arranged above the power semiconductor device to be tested, and used for capturing infrared thermal images of the power semiconductor device to be tested in different periods; An analysis and processing module is connected to the image acquisition module for receiving, analyzing and processing the infrared thermal image to obtain an abnormal heating image for determining the fault defect location of the power semiconductor device to be tested; A control module is connected to the power supply module and the image acquisition module for controlling the detection process.

10. The detection device according to claim 9, characterized in that: The device also includes a dynamic positioning module, which is fixedly connected to the image acquisition module and executes the action instructions of the control module to control the position change of the image acquisition module.

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