Threshold determination and identification method suitable for power semiconductor bonding wire fracture identification

Abstract

The invention discloses a threshold determination and identification method suitable for power semiconductor bonding wire fracture identification. The method comprises the following steps: counting an average value of total resistance of a bonding wire and a power source lead terminal of a brand new power semiconductor; aiming at the conditions that any one bonding wire is broken, any two bonding wires are broken and any three bonding wires are broken, counting the average value and the standard deviation of the total resistance change values of the bonding wires under the three conditions; determining a probability density function of a change rate threshold value of three aging values relative to a reference value based on an average value of total resistance of a bonding wire and a power source lead terminal of the brand new power semiconductor and an average value and a standard deviation of total resistance change values of the bonding wire under three conditions; and three change rate thresholds are determined through a probability density function. According to the invention, the accuracy of the identification criterion can be effectively improved, and the online identification of the fracture condition of the bonding wire can be realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of semiconductor device fault diagnosis, and particularly relates to a threshold value determination and identification method suitable for power semiconductor wire bond fracture identification. BACKGROUND

[0002] With the rapid development of new energy technology, power semiconductors have become an indispensable core component in the fields of power electronics, renewable energy and electric vehicles, and their application scale has shown a significant growth trend. In power electronics, power semiconductors improve energy efficiency through smart grids and high-voltage direct current transmission; in the field of renewable energy, solar inverters and wind power converters rely on them to achieve efficient energy conversion; in electric vehicles, they optimize motor control and battery management, extend the range and shorten the charging time.

[0003] Compared with traditional silicon materials, silicon carbide materials perform well due to their wider energy band gap, excellent heat conduction performance, higher breakdown field strength and good saturated carrier mobility. Silicon carbide devices have significant advantages in high temperature, high pressure, high frequency, high efficiency, high power density and radiation resistance, and therefore have broad application potential in power electronic circuits in the fields of power systems, rail transit, electric vehicles and aerospace. However, the high failure rate and high maintenance cost of power semiconductor devices have not been significantly improved with the introduction of silicon carbide power devices. According to the article "Condition Monitoring for Device Reliability in Power Electronic Converters: A Review", about 34% of the converter failures are caused by power semiconductor device faults. Therefore, as a focus of attention, the reliability, state monitoring and health management of silicon carbide MOSFET in long-term operation have become the focus of industry research. Since silicon carbide MOSFET works in high temperature conditions for a long time, the thermal expansion coefficients of its internal components do not match, which leads to mechanical fatigue and fracture of the wire bond under long-term high temperature cycling or transient thermal stress, seriously affecting the long-term reliability of the device.

[0004] It is an important guarantee for long-term stable operation of electrical equipment to detect the bond wire fracture inside the power semiconductor chip in time. The current methods for detecting the bond wire fracture of the Kelvin packaged power semiconductor include online measurement method and offline measurement method. In the online measurement method, the representative method is the direct measurement of the voltage between the Kelvin source and the power source proposed in Simultaneous on-state voltage and bond-wire resistance monitoring of silicon carbide MOSFETs. However, this method does not give the criterion for bond wire fault identification and has low identification sensitivity. Another method is the fault precursor based on voltage ringing proposed in Online Monitoring Bond Wires Fault of SiC MOSFETs With Kelvin Package Based on Turn-on Source Voltage Ringing. The method realizes decoupling and gives the identification criterion. However, the identification criterion given by the method is only based on the identification threshold of a number of devices, which lacks accuracy. In the offline measurement method, the representative method is the method of applying a fixed signal between the Kelvin source and the power source proposed in A Bond Wire State Monitoring Method for SiC MOSFET Devices Based on Kelvin Package. This method cannot be used for detection under the working state of the device, and no identification criterion is given.

[0005] Therefore, how to accurately detect the bond wire fracture of the power semiconductor device under the working state of the device and improve the accuracy of the identification criterion has become a technical problem to be solved by those skilled in the art. SUMMARY

[0006] To solve the above problems, the application provides a threshold determination and identification method suitable for power semiconductor bond wire fracture identification, which can identify the bond wire fracture on line and effectively improve the accuracy of the identification criterion.

[0007] In order to achieve the above technical purposes and achieve the above technical effects, the application is implemented by the following technical solutions:

[0008] In the first aspect, the application provides a threshold determination method suitable for power semiconductor bond wire fracture identification, comprising:

[0009] The average value of the total resistance of the bond wire and the power source lead terminal of a new power semiconductor is counted.

[0010] For the cases of fracture of any one bond wire, fracture of any two bond wires, and fracture of any three bond wires, the average value and the standard deviation of the total resistance change value of the three bond wires under the three conditions are counted.

[0011] According to the formula , , the probability density function of the change rate threshold of the three aging values relative to the reference value is determined, and the three change rate thresholds are determined through the probability density function, wherein, represents the average value of the change rate threshold of the aging value relative to the reference value, represents the average value of the total resistance change value of the bonding wire, represents the average value of the total resistance of the bonding wire and the power source lead terminal of the brand-new power semiconductor, represents the standard deviation of the change rate threshold of the aging value relative to the reference value, represents the standard deviation of the total resistance change value of the bonding wire.

[0012] In combination with the first aspect, optionally, the change rate threshold of the fracture of one bonding wire is determined by the probability density function determined by the average value and the standard deviation of the total resistance change value of the fracture of any one bonding wire, and the average value of the total resistance of the bonding wire and the power source lead terminal of the brand-new power semiconductor; the change rate threshold of the fracture of two bonding wires is determined by the probability density function determined by the average value and the standard deviation of the total resistance change value of the fracture of any two bonding wires, and the average value of the total resistance of the bonding wire and the power source lead terminal of the brand-new power semiconductor; the change rate threshold of the fracture of three bonding wires is determined by the probability density function determined by the average value and the standard deviation of the total resistance change value of the fracture of any three bonding wires, and the average value of the total resistance of the bonding wire and the power source lead terminal of the brand-new power semiconductor.

[0013] In combination with the first aspect, optionally, the value of the total resistance of the bonding wire and the power source lead terminal is determined by the ratio of the peak value of the drain-source current of the transient power semiconductor and the voltage between the Kelvin source and the power source at the corresponding moment, and the calculation formula is:

[0014] ,

[0015] In the formula, is the value of the total resistance of the bonding wire and the power source lead terminal, represents the resistance value of the power source lead terminal, represents the total resistance value of the bonding wire, represents the voltage between the Kelvin source and the power source at the moment when the peak value of the drain-source current of the transient power semiconductor is turned on, represents the peak value of the drain-source current of the transient power semiconductor.

[0016] In combination with the first aspect, optionally, the value of the total resistance of the bonding wire and the power source lead terminal of the new power semiconductor is determined by measuring the ratio of the peak value of the drain-source current of the on-transient new power semiconductor and the voltage between the Kelvin source and the power source at the corresponding time;

[0017] The value of the total resistance of the bonding wire and the power source lead terminal of the aged power semiconductor is determined by measuring the ratio of the peak value of the drain-source current of the on-transient aged power semiconductor and the voltage between the Kelvin source and the power source at the corresponding time;

[0018] The change value of the total resistance of the bonding wire when the bonding wire is broken is determined by subtracting the total resistance of the bonding wire and the power source lead terminal of the new power semiconductor from the total resistance of the bonding wire and the power source lead terminal of the aged power semiconductor, and the formula is:

[0019] ,

[0020] In the formula, represents the change value of the total resistance of the bonding wire when the bonding wire is broken, represents the value of the total resistance of the bonding wire and the power source lead terminal of the aged power semiconductor, represents the value of the total resistance of the bonding wire and the power source lead terminal of the new power semiconductor.

[0021] In combination with the first aspect, optionally, the probability density functions of the change rates of the three aged values relative to the reference value with respect to the threshold value are subject to normal distribution, and the probability density functions are all taken as as the threshold value, wherein, represents the average value of the change rate of the aged value relative to the reference value, represents the standard deviation of the change rate of the aged value relative to the reference value.

[0022] The second aspect of the present application provides a recognition method suitable for power semiconductor bonding wire breakage recognition, comprising:

[0023] In response to a signal that the new power semiconductor is turned on, the voltage between the Kelvin source and the power source and the voltage at the measurement point of the drain lead terminal of the on-transient power semiconductor when the drain-source current reaches the peak value are obtained, and the ratio of the voltage between the electrodes and the voltage at the measurement point is calculated as a reference value;

[0024] In response to a signal that the aged power semiconductor is turned on, the voltage between the Kelvin source and the power source and the voltage at the measurement point of the drain lead terminal of the on-transient power semiconductor when the drain-source current reaches the peak value are obtained, and the ratio of the voltage between the electrodes and the voltage at the measurement point is calculated as an aged value;

[0025] Based on the aged value and the reference value, the change rate of the aged value relative to the reference value is determined;

[0026] determine the power semiconductor wire breakage condition based on the change rate of the aging value relative to the reference value and a change rate threshold table of the aging value relative to the reference value, wherein the change rate threshold in the change rate threshold table is determined according to the method in any one of claims 1-5.

[0027] With reference to the second aspect, optionally, the calculation formula of the reference value is:

[0028] ,

[0029] wherein, represents the reference value, represents the voltage between the Kelvin source and the power source of the fresh power semiconductor measured at the time of the peak value of the drain-source current of the power semiconductor in the on-transient state, represents the voltage of the measurement point at the drain lead terminal of the fresh power semiconductor measured at the time of the peak value of the drain-source current of the power semiconductor in the on-transient state;

[0030] The calculation formula of the aging value is:

[0031] ,

[0032] wherein, represents the aging value, represents the voltage between the Kelvin source and the power source of the aged power semiconductor measured at the time of the peak value of the drain-source current of the power semiconductor in the on-transient state, represents the voltage of the measurement point at the drain lead terminal of the aged power semiconductor measured at the time of the peak value of the drain-source current of the power semiconductor in the on-transient state.

[0033] With reference to the second aspect, optionally, the calculation formula of the change rate of the aging value relative to the reference value is:

[0034] ,

[0035] wherein, represents the change rate of the aging value relative to the reference value, represents the aging value, represents the reference value.

[0036] With reference to the second aspect, optionally, the change rate threshold table of the aging value relative to the reference value includes three threshold values, respectively, a change rate threshold of one wire breakage, a change rate threshold of two wire breakages, and a change rate threshold of three wire breakages:

[0037] When the change rate of the aging value relative to the reference value is less than the change rate threshold of one wire breakage, it indicates that there is no wire breakage in the power semiconductor;

[0038] when the change rate of the aging value relative to the reference value is greater than a change rate threshold of one broken bonding wire and less than a change rate threshold of two broken bonding wires, it is indicated that there are two broken bonding wires in the power semiconductor;

[0039] when the change rate of the aging value relative to the reference value is greater than a change rate threshold of one broken bonding wire and less than a change rate threshold of two broken bonding wires, it is indicated that there are two broken bonding wires in the power semiconductor;

[0040] when the change rate of the aging value relative to the reference value is greater than a change rate threshold of one broken bonding wire and less than a change rate threshold of two broken bonding wires, it is indicated that there are two broken bonding wires in the power semiconductor.

[0041] With the second aspect, optionally, the measured point voltage at the drain lead terminal comes from a selected voltage measurement point at the drain lead terminal, and the location of the voltage measurement point at the drain lead terminal is consistent in a brand-new power semiconductor and an aged power semiconductor.

[0042] Compared with the prior art, the present application has the following beneficial effects:

[0043] The present application determines the change rate threshold through normal distribution, avoids the actual deviation caused by theoretical calculation and the lack of basis caused by sampling statistics, and improves the accuracy and reliability of bonding wire identification.

[0044] The present application identifies the bonding wire breakage condition by measuring the voltage between the Kelvin source and the power source and the voltage at the drain lead terminal voltage measurement point when the drain-source current of the power semiconductor reaches the peak value in the on-state transient, which can be identified in real time during the actual operation of the power semiconductor device, improves the work efficiency and reduces the cost; the measurement point is easy to identify when the drain-source current of the power semiconductor reaches the peak value in the on-state transient, and has high precision and high practicality. BRIEF DESCRIPTION OF DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor under the premise of the drawings.

[0046] Figure 1 It is the internal bonding wire structure diagram of the power semiconductor of the embodiment of the present application;

[0047] Figure 2 It is the identification method flow chart of the bonding wire breakage condition of the power semiconductor of the embodiment of the present application;

[0048] Figure 3 It is the internal equivalent circuit diagram of the power semiconductor of the embodiment of the present application;

[0049] Figure 4 The voltage-current waveform diagram of the power semiconductor during the on period of the embodiment of the present application. DETAILED DESCRIPTION

[0050] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work are within the protection scope of the present application.

[0051] In addition, if the present application embodiments involve "first", "second" and the like, the "first", "second" and the like are only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can be explicitly or implicitly included at least one of the features. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the fact that a person of ordinary skill in the art can realize it, and when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the protection scope required by the present application.

[0052] Embodiment 1

[0053] The present application provides a threshold determination method suitable for power semiconductor bonding wire fracture identification, and the power semiconductor in the present application refers to a Kelvin package power semiconductor; the threshold determination method specifically includes the following steps:

[0054] (1) The average value of the total resistance of the bonding wire and the power source lead terminal of a brand new power semiconductor is counted;

[0055] (2) For the case of fracture of any one bonding wire, fracture of any two bonding wires, and fracture of any three bonding wires, the average value and the standard deviation of the total resistance change value of the three bonding wires corresponding to the three cases are counted;

[0056] (3) According to the formula , , the probability density function of the change rate threshold of the three aging values relative to the reference value is determined, and the three change rate thresholds are determined through the probability density function, wherein represents the average value of the change rate threshold of the aging value relative to the reference value, represents the average value of the total resistance change value of the bonding wire, represents the average value of the total resistance of the bonding wire and the power source lead terminal of the brand new power semiconductor, a standard deviation representing a change rate threshold of the aging value relative to the reference value, a standard deviation representing a total resistance change value of the bonding wire. In the specific implementation process, , wherein, is the number of measurements, and each measurement is performed on a brand-new power semiconductor to obtain a total resistance value of the bonding wire and the power source lead terminal of the brand-new power semiconductor .

[0057] In the above scheme, the threshold is determined by the normal distribution, which avoids the actual deviation caused by theoretical calculation and the lack of basis caused by sampling statistics, and improves the accuracy and reliability of the bonding wire identification.

[0058] In one specific implementation of the embodiment, the change rate threshold of one broken bonding wire is determined by a probability density function determined by the average value and the standard deviation of the total resistance change value of any one broken bonding wire, and the average value of the total resistance of the bonding wire and the power source lead terminal of the brand-new power semiconductor; the change rate threshold of two broken bonding wires is determined by a probability density function determined by the average value and the standard deviation of the total resistance change value of any two broken bonding wires, and the average value of the total resistance of the bonding wire and the power source lead terminal of the brand-new power semiconductor; and the change rate threshold of three broken bonding wires is determined by a probability density function determined by the average value and the standard deviation of the total resistance change value of any three broken bonding wires, and the average value of the total resistance of the bonding wire and the power source lead terminal of the brand-new power semiconductor.

[0059] In one specific implementation of the embodiment, the total resistance value of the bonding wire and the power source lead terminal is determined by the ratio of the peak value of the drain-source current of the transient power semiconductor to the voltage between the Kelvin source and the power source at the corresponding time, and the calculation formula is:

[0060] ,

[0061] , wherein, represents the resistance value of the power source lead terminal, represents the total resistance value of the bonding wire, i.e. the total resistance value of all unbroken bonding wires in parallel, represents the voltage between the Kelvin source and the power source at the time when the peak value of the drain-source current of the transient power semiconductor is turned on, represents the peak value of the drain-source current of the transient power semiconductor when turned on.

[0062] In the specific implementation process, the average value of the total resistance of the bonding wire and the power source lead terminal is obtained by measuring the total resistance values of a plurality of power semiconductors of the same model, and then taking the average value.

[0063] In one specific implementation of the embodiment, the total resistance value of the bonding wire and the power source lead terminal of the new power semiconductor is determined by measuring the ratio of the peak value of the drain-source current of the new power semiconductor in the on-transient state and the voltage between the Kelvin source and the power source at the corresponding time;

[0064] The total resistance value of the bonding wire and the power source lead terminal of the aged power semiconductor is determined by measuring the ratio of the peak value of the drain-source current of the aged power semiconductor in the on-transient state and the voltage between the Kelvin source and the power source at the corresponding time;

[0065] The change value of the total resistance of the bonding wire when the bonding wire is broken is determined by subtracting the total resistance of the bonding wire and the power source lead terminal of the new power semiconductor from the total resistance of the bonding wire and the power source lead terminal of the aged power semiconductor, and the formula is:

[0066] ,

[0067] In the formula, represents the change value of the total resistance of the bonding wire when the bonding wire is broken, represents the total resistance value of the bonding wire and the power source lead terminal of the aged power semiconductor, represents the total resistance value of the bonding wire and the power source lead terminal of the new power semiconductor.

[0068] In the specific implementation, the average value of the change value of the total resistance of the bonding wire is obtained by the following formula:

[0069] ,

[0070] In the formula, is the number of measurements, one power semiconductor is measured each time to obtain one total resistance change value ;

[0071] The standard deviation of the change value of the total resistance of the bonding wire is obtained by the following formula:

[0072] .

[0073] In one specific implementation of the embodiment, the probability density functions of the change rate threshold values of the three aging values relative to the reference value all obey normal distribution, and all take as the threshold value, wherein, represents the average value of the change rate threshold value of the aging value relative to the reference value, represents the standard deviation of the change rate threshold value of the aging value relative to the reference value.

[0074] The threshold value determination method for the power semiconductor bonding wire breakage identification in the embodiment will be described in detail in combination with a specific implementation.

[0075] The threshold determination method suitable for power semiconductor bonding wire fracture identification comprises:

[0076] The average value of the total resistance of the bonding wires and the power source lead terminals of a new power device is counted, and then the average value and the standard deviation of the total resistance change value of the bonding wires are counted in the order of any one bonding wire fracture, any two bonding wire fractures, and any three bonding wire fractures, and the threshold of the change rate of the aging value relative to the reference value is determined according to the formula , , the probability density function of the threshold of the change rate of the aging value relative to the reference value is determined, and the threshold is determined through the probability density function, wherein represents the average value of the threshold of the change rate of the aging value relative to the reference value, represents the average value of the total resistance change value of the bonding wires, represents the average value of the total resistance of the bonding wires and the power source lead terminals of a new power semiconductor, represents the standard deviation of the threshold of the change rate of the aging value relative to the reference value, represents the standard deviation of the total resistance change value of the bonding wires.

[0077] Specifically, according to the formula: , is the change amount of the bonding wire resistance when the bonding wire is fractured, represents the total resistance of the bonding wires of a new power device, represents the resistance of the power source lead terminals. Due to the differences in the manufacturing of power semiconductors, the change amounts of the total resistance of the bonding wires caused by the fracture of the same number of bonding wires are different, but as industrial products, the differences are subject to normal distribution, therefore, the average value and the standard deviation of the change amount of the total resistance of the bonding wires are counted, and then the probability density function of the change amount of the total resistance of the bonding wires is calculated to accurately determine the threshold; and for qualified power semiconductors, the resistance of the drain lead terminals and the standard deviation of the total resistance value of the new bonding wires relative to their average values are negligible, therefore, when the probability density function of the change amount of the total resistance of the bonding wires is calculated, the average values thereof are treated as constants.

[0078] ​​​​Specifically, the threshold value of one broken bonding wire is determined by a probability density function of the average value and the standard deviation of the total resistance change value of any one broken bonding wire and the average value of the total resistance of the bonding wire and the power source lead terminal of the new power device; the threshold value of two broken bonding wires is determined by a probability density function of the average value and the standard deviation of the total resistance change value of any two broken bonding wires and the average value of the total resistance of the bonding wire and the power source lead terminal of the new power device; the threshold value of three broken bonding wires is determined by a probability density function of the average value and the standard deviation of the total resistance change value of any three broken bonding wires and the average value of the total resistance of the bonding wire and the power source lead terminal of the new power device.

[0079] Specifically, the total resistance value of the bonding wire and the power source lead terminal is determined by the ratio of the peak value of the drain-source current of the on-transient Kelvin package power semiconductor device and the voltage between the Kelvin source and the power source at the corresponding time, specifically, the formula is: , wherein represents the resistance value of the power source lead terminal, represents the total resistance value of the four bonding wires, represents the voltage between the Kelvin source and the power source at the time of the peak value of the drain-source current of the on-transient power semiconductor, represents the peak value of the drain-source current of the on-transient power semiconductor; the total resistance value of the bonding wire and the power source lead terminal of the new power device is determined by the ratio of the peak value of the drain-source current of the on-transient new power device and the voltage between the Kelvin source and the power source at the corresponding time; the total resistance value of the bonding wire and the power source lead terminal of the aged power device is determined by the ratio of the peak value of the drain-source current of the on-transient aged power device and the voltage between the Kelvin source and the power source at the corresponding time; the total resistance change value of the bonding wire when the bonding wire is broken is determined by subtracting the total resistance value of the bonding wire and the power source lead terminal of the new power device from the total resistance value of the bonding wire and the power source lead terminal of the aged power device, specifically, the formula is: , wherein represents the total resistance change value of the bonding wire when the bonding wire is broken, represents the total resistance value of the bonding wire and the power source lead terminal of the aged power device, represents the total resistance value of the bonding wire and the power source lead terminal of the new power device.

[0080] Specifically, the three normal distribution probability density functions determined according to the bonding wire breaking order are all taken as as the threshold value; according to the normal distribution probability density function, the probability of the random variable in the interval is 99.99966%, so The threshold value can accurately identify the number of bond wire breakages.

[0081] Embodiment 2

[0082] The identification method for identifying the bond wire breakage of the power semiconductor is provided in the embodiment of the application, and includes the following steps:

[0083] In response to a signal that a brand-new power semiconductor is turned on, the voltage between the Kelvin source electrode and the power source electrode and the voltage at the measurement point of the drain lead terminal when the drain-source current of the power semiconductor in the on-transient state reaches a peak value are obtained, and the ratio of the voltage between the electrodes to the voltage at the measurement point is calculated as a reference value;

[0084] In response to a signal that an aged power semiconductor is turned on, the voltage between the Kelvin source electrode and the power source electrode and the voltage at the measurement point of the drain lead terminal when the drain-source current of the power semiconductor in the on-transient state reaches a peak value are obtained, and the ratio of the voltage between the electrodes to the voltage at the measurement point is calculated as an aging value;

[0085] Based on the aging value and the reference value, the change rate of the aging value relative to the reference value is determined;

[0086] Based on the change rate of the aging value relative to the reference value and a change rate threshold value table of the aging value relative to the reference value, the bond wire breakage of the power semiconductor is determined, and the change rate threshold value in the change rate threshold value table is determined according to any one of the methods in the first aspect.

[0087] In the above scheme, the bond wire breakage is identified by measuring the voltage between the Kelvin source electrode and the power source electrode and the voltage at the measurement point of the drain lead terminal when the drain-source current of the power semiconductor in the on-transient state reaches a peak value, which can be identified in real time during the actual operation of the power semiconductor device, thereby improving the work efficiency and reducing the cost. The measurement point at which the drain-source current of the power semiconductor in the on-transient state reaches a peak value is easy to identify, and has high precision and high practicability.

[0088] In the specific implementation process, as shown in Figure 2 The identification method for identifying the bond wire breakage of the power semiconductor specifically includes the following steps:

[0089] Step S1: selecting a voltage measurement point at the drain lead terminal of the power semiconductor; the power semiconductor refers to a Kelvin packaged power semiconductor device;

[0090] Step S2: turning on a brand-new Kelvin packaged power semiconductor device, measuring the voltage between the Kelvin source electrode and the power source electrode and the voltage at the measurement point of the drain lead terminal when the drain-source current in the on-transient state reaches a peak value, and calculating the ratio of the voltage between the electrodes to the voltage at the measurement point as a reference value;

[0091] Step S3: Turn on the aged Kelvin packaged power semiconductor device, measure the voltage between the Kelvin source and the power source when the on-state transient drain-source current reaches the peak, the voltage at the measurement point of the drain lead terminal, and calculate the ratio of the voltage between the electrodes and the voltage at the measurement point as the aging value; wherein the voltage at the measurement point of the drain lead terminal is from the selected voltage measurement point at the drain lead terminal, the position of the voltage measurement point at the drain lead terminal is consistent in the new power semiconductor and the aged power semiconductor, and the position should be kept unchanged during the whole identification process;

[0092] Step S4: Determine the change rate of the aging value relative to the reference value according to the change rate formula of the aging value relative to the reference value;

[0093] Step S5: Determine the bonding wire fracture condition of the Kelvin packaged power semiconductor device through the change rate threshold table of the aging value relative to the reference value.

[0094] As shown in Figure 3 The voltage between the Kelvin source and the power source in steps S2 and S3 is the voltage between the device terminal KS and the device terminal S, the device terminal KS refers to the Kelvin source, the device terminal S refers to the power source, and the voltage at the measurement point is the voltage on the terminal S. Since the device terminal is inherent to the power semiconductor device, no additional device needs to be added, greatly reducing the use cost. G-LT Rg is the gate lead terminal resistance, G_BW Rg is the gate bonding wire resistance, G_P Rg is the gate internal parasitic resistance, KS-LT Rk is the Kelvin source lead terminal resistance, KS_BW Rk is the Kelvin source bonding wire resistance, S_P Rs is the source internal parasitic resistance, D-LT Rd is the drain lead terminal resistance, D_P Rd is the drain internal parasitic resistance, S-LT Rp is the power source lead terminal resistance, S_BW Lp is the power source bonding wire inductance, G-LT Lg is the gate lead terminal inductance, G_BW Lg is the gate bonding wire inductance, G_P Lg is the gate internal parasitic inductance, KS-LT Lk is the Kelvin source lead terminal inductance, KS_BW Lk is the Kelvin source bonding wire inductance, S_P Ls is the source internal parasitic inductance, D-LT Ld is the drain lead terminal inductance, D_P Ld is the drain internal parasitic inductance, S-LT Lp is the power source lead terminal inductance, S_BW Lp is the power source bonding wire inductance.

[0095] In one specific embodiment of the present application, as shown in Figure 3 and Figure 4 , the calculation formula of the reference value in the step S2 and the step S3 is:

[0096] ,

[0097] In the formula, represents the reference value, represents the voltage between the Kelvin source and the power source of the fresh power semiconductor measured at the moment when the drain-source current of the power semiconductor reaches the peak value in the on-state transient, represents the voltage at the measurement point of the drain lead terminal of the fresh power semiconductor measured at the moment when the drain-source current of the power semiconductor reaches the peak value in the on-state transient;

[0098] The calculation formula of the aging value is:

[0099] ,

[0100] In the formula, represents the aging value, represents the voltage between the Kelvin source and the power source of the aged power semiconductor measured at the moment when the drain-source current of the power semiconductor reaches the peak value in the on-state transient, represents the voltage at the measurement point of the drain lead terminal of the aged power semiconductor measured at the moment when the drain-source current of the power semiconductor reaches the peak value in the on-state transient.

[0101] In the on-state transient of the power semiconductor, when the drain-source current reaches the peak value, the rate of change of the drain-source current is zero, the voltage drop caused by the parasitic inductance of the Kelvin source and power source loop and the parasitic inductance at the voltage measurement point of the drain lead terminal is zero, and at this moment, it is the starting moment of the Miller platform, at this moment, the gate current has decreased to a lower value at a low rate, therefore, the voltage drop on the parasitic inductance and parasitic resistance between the gate and the Kelvin source can be ignored, and the voltage between the Kelvin source and the power source can be approximately generated only by the drain-source current, according to Ohm's law: wherein, represents the voltage between the Kelvin source and the power source, represents the resistance of the power source lead terminal, represents the total resistance of the bonding wire, represents the peak value of the drain-source current; represents the voltage at the voltage measurement point of the drain lead terminal, represents the resistance at the voltage measurement point of the drain lead terminal.

[0102] As shown in Figure 3 and Figure 4 , four bonding wires (i.e. Figure 1Since b1, b2, b3, and b4 are connected in parallel, the total resistance of the bond wire is expressed as follows: ,in, This represents the total resistance of the bonded wires. Indicates bond line resistance value When any one of the bond wires breaks, the corresponding resistance becomes infinite, and the total resistance of the bond wires also increases. Since the four bond wires are cylinders of equal length and radius, their resistances are all equal. Because the bond wires, the source-drain lead terminal resistance, and the voltage measurement point resistance at the drain-drain lead terminal are in the same branch, the drain-source current flowing through them is the same current, therefore the peak value of the drain-source current is also the same. Therefore, the ratio formula is: ,in, Indicates the ratio; because and The changes do not occur significantly throughout the entire lifespan of power semiconductor devices, therefore, The change only occurs when the bond wire breaks, i.e. = It can characterize entirely new bond lines, serving as a baseline value; where This represents the total bond wire resistance of a brand new power device. The bond lines of aging power devices can be characterized as aging values, where... This indicates the bond wires of the aging power device.

[0103] In one specific embodiment of the present invention, the formula for calculating the rate of change of the aging value relative to the reference value is as follows:

[0104] ,

[0105] in This represents the change in bond wire resistance when the bond wire breaks; it can be seen that, due to The power semiconductor does not undergo significant changes throughout its entire lifespan. For the same type of power semiconductor, the value is fixed, therefore The value is only related to The value is related to the theoretical calculation, when a bond wire breaks... Compared to The rate of change is 33%, when two bond lines break. Compared to The rate of change is 100%, and the three bond lines break. Compared to The rate of change is 300%, therefore It can accurately reflect the breakage status of the bond wire.

[0106] In one specific embodiment of the present invention, the threshold table for the rate of change of the aging value relative to the reference value includes three thresholds: the threshold for the rate of change of one bond wire breakage, the threshold for the rate of change of two bond wire breakages, and the threshold for the rate of change of three bond wire breakages.

[0107] When the rate of change of the aging value relative to the reference value is less than the rate of change threshold of a single bond wire breakage, it indicates that there are no bond wire breaks in the power semiconductor.

[0108] When the rate of change of the aging value relative to the reference value is greater than the rate of change of one bond wire breakage and less than the rate of change of two bond wire breakages, it indicates that one bond wire in the power semiconductor has broken.

[0109] When the rate of change of the aging value relative to the reference value is greater than the rate of change of two bond wires breaking but less than the threshold of the rate of change of three bond wires breaking, it indicates that two bond wires in the power semiconductor are broken.

[0110] When the rate of change of the aging value relative to the reference value is greater than the threshold of the rate of change of the three bond wires breaking, it indicates that there are three bond wires broken in the power semiconductor.

[0111] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0112] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0113] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a processFigure 1 one or more processes and / or blocks Figure 1 the function specified in the one or more blocks.

[0114] These computer program instructions can also be loaded into computer or other programmable data processing devices, so that a series of operational steps are performed on the computer or other programmable data processing devices to generate a computer implemented process, so that the instructions executed on the computer or other programmable data processing devices provide steps for implementing the function specified in the flowchart Figure 1 one or more processes and / or blocks Figure 1 the function specified in the one or more blocks.

[0115] The embodiments of the present application are described above with reference to the accompanying drawings, but the present application is not limited to the above-described specific embodiments, and the above-described specific embodiments are merely illustrative, not restrictive, and a person of ordinary skill in the art can make many forms under the inspiration of the present application without departing from the purpose of the present application and the scope protected by the claims, and these all belong to the protection of the present application.

[0116] The basic principles and main features of the present application and the advantages of the present application are shown and described above. It should be understood by those skilled in the art that the present application is not limited to the above-described embodiments, and the above-described embodiments and descriptions in the specification are only illustrative of the principles of the present application, and various changes and improvements can be made to the present application without departing from the spirit and scope of the present application, and these changes and improvements all fall within the scope of the present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A threshold determination method suitable for power semiconductor wire bond fracture identification, characterized in that, The method comprises the following steps: The average value of the total resistance of the bonding wire and the power source lead terminal of the new power semiconductor is counted; The average value and the standard deviation of the total resistance change value of the three bonding wires in the case of any one bonding wire breaking, any two bonding wires breaking, and any three bonding wires breaking are counted; According to the formula , , the probability density function of the three aging value change rate thresholds relative to the reference value is determined, and the three change rate thresholds are determined through the probability density function, wherein, represents the average value of the change rate threshold of the aging value relative to the reference value, represents the average value of the total resistance change value of the bonding wire, represents the average value of the total resistance of the bonding wire and the power source lead terminal of the brand new power semiconductor, represents the standard deviation of the change rate threshold of the aging value relative to the reference value, represents the standard deviation of the total resistance change value of the bonding wire.

2. The threshold determination method for wire bond fracture identification of power semiconductor according to claim 1, characterized in that: The change rate threshold of one broken bonding wire is determined by the probability density function of the average value and the standard deviation of the total resistance change value of the broken bonding wire and the average value of the total resistance of the bonding wire and the power source lead terminal of the new power semiconductor; the change rate threshold of two broken bonding wires is determined by the probability density function of the average value and the standard deviation of the total resistance change value of the broken bonding wire and the average value of the total resistance of the bonding wire and the power source lead terminal of the new power semiconductor; and the change rate threshold of three broken bonding wires is determined by the probability density function of the average value and the standard deviation of the total resistance change value of the broken bonding wire and the average value of the total resistance of the bonding wire and the power source lead terminal of the new power semiconductor.

3. The threshold determination method for wire bond fracture identification of power semiconductor according to claim 1, wherein: The value of the total resistance of the bonding wire and the power source lead terminal is determined by the ratio of the peak value of the drain-source current of the transient power semiconductor to the voltage between the Kelvin source and the power source at the corresponding time, and the calculation formula is: ， In the formula, is the value of the total resistance of the bonding wire and the power source lead terminal, denotes the resistance value of the power source lead terminal, denotes the total resistance value of the bonding wire, denotes the voltage between the Kelvin source and the power source at the time of the peak value of the drain-source current of the power semiconductor in the on-transient state, denotes the peak value of the drain-source current of the power semiconductor in the on-transient state.

4. The threshold determination method for wire bond fracture identification of power semiconductor according to claim 3, characterized in that: The value of the total resistance of the bonding wire and the power source lead terminal of the new power semiconductor is determined by measuring the peak value of the drain-source current of the transient new power semiconductor and the ratio of the voltage between the Kelvin source and the power source at the corresponding time; The value of the total resistance of the bonding wire and the power source lead terminal of the aged power semiconductor is determined by measuring the peak value of the drain-source current of the transient aged power semiconductor and the ratio of the voltage between the Kelvin source and the power source at the corresponding time; The total resistance change value of the bonding wire when the bonding wire breaks is determined by subtracting the total resistance of the bonding wire and the power source lead terminal of the new power semiconductor from the total resistance of the bonding wire and the power source lead terminal of the aged power semiconductor, and the formula is: ， In the formula, represents the total resistance change value of the bonding wire at the time of the bonding wire breakage, represents the value of the total resistance of the bonding wire and the power source lead terminal of the aged power semiconductor, represents the value of the total resistance of the bonding wire and the power source lead terminal of the brand-new power semiconductor.

5. The method for threshold determination for wire bond fracture identification of power semiconductor according to claim 1, wherein: The probability density functions of the three aging values with respect to the change rate threshold of the reference value are subject to normal distribution, and are taken as as a threshold value, wherein represents the average value of the change rate threshold of the aging value with respect to the reference value, represents the standard deviation of the change rate threshold of the aging value with respect to the reference value.

6. An identification method suitable for power semiconductor wire bond fracture identification, characterized by, The method comprises the following steps: In response to the signal that the new power semiconductor is turned on, the voltage between the Kelvin source and the power source and the voltage at the measurement point of the drain lead terminal when the drain-source current of the transient power semiconductor reaches the peak value are obtained, the ratio of the voltage between the Kelvin source and the power source to the voltage at the measurement point is calculated as a reference value; In response to the signal that the aged power semiconductor is turned on, the voltage between the Kelvin source and the power source and the voltage at the measurement point of the drain lead terminal when the drain-source current of the transient power semiconductor reaches the peak value are obtained, the ratio of the voltage between the Kelvin source and the power source to the voltage at the measurement point is calculated as an aging value; Based on the aging value and the reference value, the change rate of the aging value relative to the reference value is determined; Based on the change rate of the aging value relative to the reference value and the change rate threshold table of the aging value relative to the reference value, the bonding wire breaking condition of the power semiconductor is determined, and the change rate threshold in the change rate threshold table is determined according to the method in any one of claims 1-5.

7. The identification method according to claim 6, characterized in that, The calculation formula of the reference value is: ， wherein represents a reference value, represents a voltage between the Kelvin source and the power source of the fresh power semiconductor measured at the time of the peak of the drain-source current of the turned-on transient power semiconductor, represents a voltage at the measurement point at the drain lead terminal of the fresh power semiconductor measured at the time of the peak of the drain-source current of the turned-on transient power semiconductor. The calculation formula of the aging value is: ， In the formulae, denotes the aging value, denotes the voltage between the Kelvin source and the power source of the aged power semiconductor measured at the time of the peak of the drain-source current of the turned-on transient power semiconductor, denotes the voltage at the measurement point at the drain lead terminal of the aged power semiconductor measured at the time of the peak of the drain-source current of the turned-on transient power semiconductor.

8. The identification method according to claim 6, wherein The calculation formula of the change rate of the aging value relative to the reference value is: ， In the formula, represents a rate of change of the aging value with respect to the reference value, represents the aging value, represents the reference value.

9. The identification method according to claim 6, wherein The change rate threshold table of the aging value relative to the reference value includes three thresholds, respectively, a change rate threshold of one broken bonding wire, a change rate threshold of two broken bonding wires, and a change rate threshold of three broken bonding wires: When the change rate of the aging value relative to the reference value is less than the change rate threshold of one broken bonding wire, it indicates that there is no broken bonding wire in the power semiconductor; When the change rate of the aging value relative to the reference value is greater than the change rate threshold of one broken bonding wire and less than the change rate threshold of two broken bonding wires, it indicates that there is one broken bonding wire in the power semiconductor; When the change rate of the aging value relative to the reference value is greater than the change rate threshold of two broken bonding wires and less than the change rate threshold of three broken bonding wires, it indicates that there are two broken bonding wires in the power semiconductor; When the change rate of the aging value relative to the reference value is greater than the change rate threshold of three broken bonding wires, it indicates that there are three broken bonding wires in the power semiconductor.

10. The identification method according to claim 6, wherein The measured point voltage at the drain lead terminal comes from a selected voltage measurement point at the drain lead terminal, and the position of the voltage measurement point at the drain lead terminal is consistent in the new power semiconductor and the aged power semiconductor.

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