Power device package aging monitoring method, monitoring circuit, driving method and device

Abstract

The present application provides a power device package aging monitoring method, a monitoring circuit, a driving method and a device. The method includes: heating a device under test according to a first heating pulse to raise the junction temperature to a preset maximum junction temperature; dissipating heat from the device under test, and the heat dissipation duration is determined according to the thermal time constant sum of the auxiliary package film layer and the target package film layer. The package structure of the device under test includes an auxiliary package film layer and a target package film layer, and the auxiliary package film layer is located between the target package film layer and the heat source; obtaining the first current junction temperature of the device under test; heating the device under test according to a second heating pulse, and the heating duration is determined according to the thermal time constant sum of the auxiliary package film layer, and the second heating pulse is determined according to the first heating pulse; obtaining the second current junction temperature of the device under test; determining the current thermal resistance of the target package film layer according to the first current junction temperature, the second current junction temperature and the second heating pulse; and judging the aging state of the target package film layer according to the current thermal resistance and the preset thermal resistance.

Description

Technical Field

[0001] The present application relates to the technical field of power device detection, and particularly to a method for monitoring the aging of a power device package, a monitoring circuit, a driving method, and a device. Background Art

[0002] The package is an important part of a power device, and its function is to provide support and protection for the chip and connect it to an external circuit. The package is one of the weakest links in the device. Package aging mainly occurs in structures directly connected to the chip, such as chip solder, bonding wires, and the chip-molybdenum contact interface. Online monitoring of device package aging is a necessary step in studying the reliability of device packages and iterating device package structures, and is of great significance for analyzing the failure mechanism of device packages, establishing failure judgment criteria, and aging life models.

[0003] In traditional methods for monitoring the aging of power device packages, the aging degree of the power device package structure is usually determined by the junction-to-case thermal resistance and the on-state voltage drop of the power device. However, the junction-to-case thermal resistance of the power device includes the total thermal resistance of all the film layers in the package structure, and the on-state voltage drop of the power device includes the total voltage drop of all the film layers in the package structure, and it is impossible to characterize the aging state of a specific structure in the package structure. Therefore, when it is determined that the package structure of the power device is aged through the junction-to-case thermal resistance and the on-state voltage drop, it is difficult to locate the aging problem. The aging problems of some package film layers cannot cause the parameter changes of the entire package structure to reach the failure criterion, which will reduce the accuracy of aging monitoring. At the same time, it is impossible to monitor the package film layers prone to aging separately, affecting the monitoring quality and monitoring efficiency of aging monitoring. Summary of the Invention

[0004] Based on this, in view of the above technical problems, it is necessary to provide a method for monitoring the aging of a power device package, a monitoring circuit, a driving method, and a device, which can monitor the aging of some film layers in the power device package structure, so as to locate the aging of the power device package structure, improve the accuracy of the monitoring result, and improve the monitoring quality and monitoring efficiency.

[0005] In the first aspect of the embodiments of the present application, a method for monitoring the aging of a power device package is provided, including:

[0006] Heating the power device to be detected according to a first heating pulse so that the junction temperature of the power device to be detected rises to a preset maximum junction temperature;

[0007] Cool the power device to be detected whose current junction temperature is equal to the preset maximum junction temperature, where the cooling time of the power device to be detected is determined according to a first thermal time constant, the first thermal time constant is equal to the sum of the thermal time constants of the auxiliary encapsulation film layer and the target encapsulation film layer, the encapsulation structure of the power device to be detected includes the auxiliary encapsulation film layer and the target encapsulation film layer, and the auxiliary encapsulation film layer is located between the target encapsulation film layer and the heat source in contact with the power device to be detected;

[0008] Obtain the first current junction temperature of the power device to be detected;

[0009] Heat the power device to be detected according to a second heating pulse, where the heating time of the power device to be detected is equal to the heating time of the second heating pulse, the heating time of the second heating pulse is determined according to a second thermal time constant, the second thermal time constant is equal to the sum of the thermal time constants of all the auxiliary encapsulation film layers, and the second heating pulse power is determined according to the first heating pulse power, the first thermal time constant and the second thermal time constant;

[0010] Obtain the second current junction temperature of the power device to be detected;

[0011] Determine the current thermal resistance of the target encapsulation film layer according to the first current junction temperature, the second current junction temperature and the second heating pulse power;

[0012] Judge the aging state of the target encapsulation film layer according to the current thermal resistance and the preset thermal resistance of the target encapsulation film layer.

[0013] In some embodiments, before the step of heating the power device to be detected according to the second heating pulse, it further includes:

[0014] Determine the thermal resistance values and heat capacity values of the auxiliary encapsulation film layer and the target encapsulation film layer according to the thermal conductivity, specific heat capacity, density and film layer thickness of the auxiliary encapsulation film layer and the target encapsulation film layer;

[0015] Determine the first thermal time constant according to the thermal resistance values and heat capacity values of the auxiliary encapsulation film layer and the target encapsulation film layer, where the first thermal time constant is the sum of the products of the thermal resistance values and heat capacity values of the corresponding film layers in the auxiliary encapsulation film layer and the target encapsulation film layer, and the second thermal time constant is the sum of the products of the thermal resistance values and heat capacity values of the corresponding film layers in all the auxiliary encapsulation film layers.

[0016] In some embodiments, when the power device to be detected is a soldering type device, the target encapsulation film layer includes a chip solder layer and a system solder layer;

[0017] When the power device to be detected is a press-fit device, the target encapsulation film layer includes a welding layer and a contact interface, where the contact interface includes the contact interface between the power chip and the metal heat dissipation layer.

[0018] In some embodiments, determining the aging state of the target encapsulation film layer according to the current thermal resistance and the preset thermal resistance of the target encapsulation film layer includes:

[0019] When the current thermal resistance is greater than the preset thermal resistance, it is determined that the target encapsulation film layer is aged, where the preset thermal resistance is determined according to the initial thermal resistance of the target encapsulation film layer.

[0020] In some embodiments, the heat dissipation time is equal to three times the first thermal time constant;

[0021] The heating time of the second heating pulse is equal to three times the second thermal time constant.

[0022] In some embodiments, the second heating pulse power is equal to the product of the first heating pulse power and the target coefficient, where the target coefficient is equal to the ratio of the first thermal time constant to the total thermal time constant of the encapsulation structure.

[0023] In some embodiments, when the power device to be detected is a double-sided heat dissipation device, the power device to be detected includes the power chip and two symmetrically arranged encapsulation structures, and the power chip is located between the two encapsulation structures;

[0024] Heating the power device to be detected according to the first heating pulse includes:

[0025] Applying a first step current to the power chip at the center of the power device to be detected, so that the power chip heats the encapsulation structure according to the first heating pulse, and the junction temperature of the power device to be detected rises to the preset maximum junction temperature;

[0026] Heating the power device to be detected according to the second heating pulse includes:

[0027] Applying a second step current to the power chip at the center of the power device to be detected, so that the power chip heats the encapsulation structure according to the second heating pulse, where the heating time of the power device to be detected is equal to the heating time of the second heating pulse;

[0028] Determining the current thermal resistance of the target encapsulation film layer according to the first current junction temperature, the second current junction temperature and the second heating pulse power includes:

[0029] Determine the first current thermal resistance of the target encapsulation film layer in the encapsulation structure on one side of the power chip according to the first current junction temperature, the second current junction temperature, and the heating power transferred by the second heating pulse to the encapsulation structure on one side of the power chip;

[0030] Determine the second current thermal resistance of the target encapsulation film layer in the encapsulation structure on the other side of the power chip according to the first current junction temperature, the second current junction temperature, and the heating power transferred by the second heating pulse to the encapsulation structure on the other side of the power chip;

[0031] Determine the current thermal resistance of the target encapsulation film layer according to the first current thermal resistance and the second current thermal resistance.

[0032] In a second aspect of the embodiments of the present application, a power device package aging monitoring circuit is provided, including:

[0033] A monitoring circuit, the monitoring circuit is used to be connected in parallel with the power device to be detected, the monitoring circuit is used to provide a monitoring current to obtain the junction temperature of the power device to be detected, and determine the current thermal resistance of the target encapsulation film layer in the power device to be detected according to the first current junction temperature and the second current junction temperature of the power device to be detected, so as to determine the aging state of the target encapsulation film layer according to the current thermal resistance;

[0034] A first pulse circuit, connected in parallel with the monitoring circuit, the first pulse circuit includes a first pulse current source and a first switch, the first pulse current source and the first switch are connected in series, the first pulse current source is used to provide a first heating pulse to heat the power device to be detected, and the first switch is used to control the heating time of the first pulse current source so that the junction temperature of the power device to be detected rises to a preset maximum junction temperature;

[0035] A second pulse circuit, connected in parallel with the monitoring circuit, the second pulse circuit includes a second pulse current source and a second switch, the second pulse current source and the second switch are connected in series, the second pulse current source is used to provide a second heating pulse to heat the power device to be detected, the second switch is used to control the heating time of the second pulse current source, and the heating time of the second pulse current source is determined according to a second thermal time constant, and the second thermal time constant is equal to the sum of the thermal time constants of all the auxiliary encapsulation film layers of the power device to be detected;

[0036] Wherein, the first switch and the second switch are conductively connected at intervals, and the conduction interval duration of the first switch and the second switch is equal to the heat dissipation time.

[0037] In the third aspect of the embodiments of the present application, a driving method for a power device package aging monitoring circuit is provided, which is used to drive the power device package aging monitoring circuit as described in the second aspect above. The driving method of the power device package aging monitoring circuit includes:

[0038] Providing a monitoring power supply to the power device to be detected through a monitoring circuit to obtain the junction temperature of the power device to be detected;

[0039] Closing the first switch in the first pulse circuit, turning on the first pulse current source in the first pulse circuit, and turning off the second switch in the second pulse circuit, so that the first pulse current source heats the power device to be detected according to the first heating pulse, and raises the junction temperature of the power device to be detected to a preset maximum junction temperature;

[0040] Turning off the first switch and the second switch, and dissipating heat from the power device to be detected whose current junction temperature is equal to the preset maximum junction temperature, where the heat dissipation duration of the power device to be detected is equal to the heat dissipation time;

[0041] Providing a monitoring power supply to the power device to be detected through the monitoring circuit to obtain the first current junction temperature of the power device to be detected;

[0042] Closing the second switch, turning on the second pulse current source in the second pulse circuit, so that the second pulse current source heats the power device to be detected according to the second heating pulse, where the heating time of the power device to be detected is equal to the heating time of the second heating pulse;

[0043] Providing a monitoring power supply to the power device to be detected through the monitoring circuit to obtain the second current junction temperature of the power device to be detected, determining the current thermal resistance of the target encapsulation film layer according to the first current junction temperature, the second current junction temperature, and the second heating pulse power, and judging the aging state of the target encapsulation film layer according to the current thermal resistance and the preset thermal resistance of the target encapsulation film layer.

[0044] In the fourth aspect of the embodiments of the present application, a power device package aging monitoring device is provided, including:

[0045] A first heating module, configured to heat the power device to be detected according to a first heating pulse, so as to raise the junction temperature of the power device to be detected to a preset maximum junction temperature;

[0046] A heat dissipation module for dissipating heat from the power device to be detected whose current junction temperature is equal to the preset maximum junction temperature. The heat dissipation time of the power device to be detected is determined according to a first thermal time constant, which is equal to the sum of the thermal time constants of the auxiliary encapsulation film layer and the target encapsulation film layer. The encapsulation structure of the power device to be detected includes the auxiliary encapsulation film layer and the target encapsulation film layer, and the auxiliary encapsulation film layer is located between the target encapsulation film layer and the heat source in contact with the power device to be detected;

[0047] A first temperature measurement module for obtaining the first current junction temperature of the power device to be detected;

[0048] A second heating module for heating the power device to be detected according to a second heating pulse. The heating time of the second heating pulse is determined according to a second thermal time constant, which is equal to the sum of the thermal time constants of all the auxiliary encapsulation film layers. The second heating pulse power is determined according to the first heating pulse power, the first thermal time constant, and the second thermal time constant;

[0049] A second temperature measurement module for obtaining the second current junction temperature of the power device to be detected;

[0050] A first determination module for determining the current thermal resistance of the target encapsulation film layer according to the first current junction temperature, the second current junction temperature, and the second heating pulse power;

[0051] A second determination module for judging the aging state of the target encapsulation film layer according to the current thermal resistance and the preset thermal resistance of the target encapsulation film layer.

[0052] The power device package aging monitoring method, monitoring circuit, driving method and device provided by the embodiments of the present application first heat the junction temperature of the power device to be detected to a preset maximum junction temperature by a first heating pulse and then stop heating, forming a first-order zero-state thermal response inside the package structure, constructing complete thermal path information inside the package structure, so that heat can reach different film layers in the package structure at different times. Then, the power device to be detected is cooled, so that the cooling time of the power device to be detected is equal to the cooling time. According to the heat transfer relationship of each film layer in the package structure of the power device to be detected, after the natural cooling of the target package film layer in the package structure and the auxiliary package film layer between the target package film layer and the heat source is completed, the first current junction temperature after the natural cooling of the target package film layer is obtained. Further, by adjusting the heating pulse to a second heating pulse and reheating the power device package structure, the auxiliary package film layer between the target package film layer and the heat source is reheated to the state before natural cooling, changing the thermal transient process of the target package film layer, restoring the thermal information of the target package film layer, and obtaining the second current junction temperature of the target package film layer at this time. According to the difference between the first current junction temperature and the second current junction temperature, the change in the junction temperature of the power device before and after cooling of the target package film layer can be determined, so that the current thermal resistance of the target package film layer can be determined, which is convenient for judging whether the target package film layer is aged based on the difference between the current thermal resistance of the target package film layer and the preset thermal resistance. Therefore, without disassembling and assembling the package structure, the monitoring of a specific target package film layer in the power device package structure can be realized, and the aging condition of the whole package structure can be judged by the aging condition of a single target package film layer, which can improve the accuracy and reliability of the aging monitoring method, locate the aging problem of the power device package structure, improve the practicability and effectiveness of the aging monitoring method, and improve the monitoring quality and monitoring efficiency of the aging monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related art, the following will briefly introduce the drawings required for the description of the embodiments or the related art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained according to these drawings without creative efforts.

[0054] Figure 1 It is a schematic flowchart of the power device package aging monitoring method provided by the embodiments of the present application;

[0055] Figure 2 It is a schematic structural diagram of the power device to be detected in the power device package aging monitoring method provided by the embodiments of the present application;

[0056] Figure 3The first-order zero-state response heating pulse variation curve of the thin plate simplified model for the power device package aging monitoring method provided by the embodiment of the present application;

[0057] Figure 4 The junction temperature variation curve of the first-order zero-state response of the thin plate simplified model for the power device package aging monitoring method provided by the embodiment of the present application;

[0058] Figure 5 The schematic diagram of the thin plate simplified model for the power device package aging monitoring method provided by the embodiment of the present application;

[0059] Figure 6 The thin plate temperature variation curve for the power device package aging monitoring method provided by the embodiment of the present application;

[0060] Figure 7 The schematic diagram of the double-sided heat dissipation device model for the power device package aging monitoring method provided by the embodiment of the present application;

[0061] Figure 8 The schematic structural diagram of the power device package aging monitoring circuit provided by the embodiment of the present application;

[0062] Figure 9 The schematic flowchart of the driving method of the power device package aging monitoring circuit provided by the embodiment of the present application;

[0063] Figure 10 The schematic structural diagram of the power device package aging monitoring device provided by the embodiment of the present application. Specific embodiments

[0064] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0065] Packaging is an important part of power devices. Its function is to provide support and protection for the chip and connect it to the external circuit. Packaging is one of the weakest links in the device. Packaging aging mainly focuses on the structures directly connected to the chip, such as chip solder, bonding wires, and the chip-molybdenum sheet contact interface. Online monitoring of device packaging aging is a necessary step in studying the reliability of device packaging and iterating the device packaging structure, and is of great significance for analyzing the failure mechanism of device packaging, establishing failure judgment criteria, and aging life models.

[0066] In traditional aging monitoring methods for power device packages, the aging degree of the power device package structure is usually determined by the junction-to-case thermal resistance and the on-state voltage drop of the power device. When the junction-to-case thermal resistance or the on-state voltage drop rises by 20% compared to the initial value or exceeds the specified limit, it is determined that the package structure of the power device fails.

[0067] However, the junction-to-case thermal resistance of a power device includes the total thermal resistance of all the film layers within the package structure. The structural degradation of a specific target package film layer in the package structure will cause an increase in the structural thermal resistance of that film layer, which in turn will lead to an increase in the junction-to-case thermal resistance. For example, when the target package film layer is the welding module of the package structure, the proportion of the structural thermal resistance of the welding module in the total junction-to-case thermal resistance is less than 20%. Therefore, when only the welding module shows aging, it is impossible to cause the change in the total junction-to-case thermal resistance to reach the value corresponding to the failure criterion, resulting in a decrease in the accuracy of the aging monitoring results. Similarly, there will also be a problem of inaccurate monitoring results when judging the aging of bonding wires through the on-state voltage drop. Therefore, when determining the aging of the power device package structure through the junction-to-case thermal resistance and the on-state voltage drop, the accuracy of the aging monitoring results is relatively low, the risk of misjudgment is relatively high, it is difficult to locate the aging problem, and at the same time, it is impossible to separately monitor the package film layers that are prone to aging, affecting the monitoring quality and efficiency of aging monitoring.

[0068] In view of this, it is an urgent technical problem to be solved at present to propose a power device package aging monitoring method that can locate the aging of the power device package structure, improve the accuracy of the monitoring results, and can be used for the thermal characteristic test of power devices for thermal characteristic resolution.

[0069] As Figure 1 shown, in the first aspect of the embodiment of the present application, a power device package aging monitoring method is provided, including:

[0070] Step S110: Heat the power device to be detected according to the first heating pulse so that the junction temperature of the power device to be detected rises to a preset maximum junction temperature.

[0071] Exemplarily, the preset maximum junction temperature can be the temperature of the power device to be detected in the thermal steady state. Before heating the power device to be detected, the junction temperature of the power device to be detected is the preset minimum junction temperature.

[0072] Exemplarily, each layer structure on the heat transfer path of the power device can be approximated as closely stacked thin plates. Before the step of heating the power device to be detected according to the first heating pulse, it is necessary to calculate the monitoring window corresponding to the target package film layer according to the pulse monitoring window selection rule.

[0073] Step S120: Cool the power device to be detected whose current junction temperature is equal to the preset maximum junction temperature. The cooling time of the power device to be detected is determined according to the first thermal time constant, and the first thermal time constant is equal to the sum of the thermal time constants of the auxiliary encapsulation film layer and the target encapsulation film layer. The encapsulation structure of the power device to be detected includes an auxiliary encapsulation film layer and a target encapsulation film layer, and the auxiliary encapsulation film layer is located between the target encapsulation film layer and the heat source in contact with the power device to be detected.

[0074] Exemplarily, when the power device to be detected is the power device to be detected as shown in Figure 2 the heat transfer direction inside the power device to be detected is from the power chip to the radiator. Among them, the auxiliary encapsulation film layer includes a chip, solder, DBC (Direct Bonding Copper), and system solder, and the target encapsulation film layer is a copper substrate layer.

[0075] Step S130: Obtain the first current junction temperature of the power device to be detected.

[0076] Exemplarily, the first current junction temperature of the power device to be detected can be determined by applying a measurement current with a small current value to the power device to be detected and using the on-state voltage drop method. Before the measurement step of the current junction temperature, a calibration experiment can be carried out in advance to draw the relationship curve between the junction temperature and the temperature-sensitive electrical parameter. During the process of obtaining the junction temperature, based on the collected temperature-sensitive electrical parameter, the junction temperature is inversely deduced based on the relationship curve.

[0077] Step S140: Heat the power device to be detected according to the second heating pulse. The heating time of the second heating pulse is determined according to the second thermal time constant, and the second thermal time constant is equal to the sum of the thermal time constants of all the auxiliary encapsulation film layers. The second heating pulse is determined according to the first heating pulse, the first thermal time constant, and the second thermal time constant.

[0078] Exemplarily, the power of the measurement pulse is jointly determined by the heating pulse power and the monitoring window. The thermal path information of the layer structure can be restored through the measurement pulse based on the monitoring window. Among them, the second heating pulse power can be obtained by:

[0079] (1)

[0080] is determined, where is the first heating pulse power, is the thermal time constant of the nth layer encapsulation structure, where n = 1, 2, …… i, is the thermal time constant of the ith layer encapsulation structure. It can be obtained by:

[0081] (2)

[0082] Determine the first heating pulse . Among them, is the on-state voltage drop at the moment before the heat dissipation starts, is the load current at the moment before the heat dissipation starts.

[0083] Step S150, obtain the second current junction temperature of the power device to be detected.

[0084] It should be noted that, as Figure 3 and Figure 4 shown, during the time period from to , the load current change curve for heating the power device to be detected corresponds to the junction temperature change curve of the power device to be detected. During , the load current provides the first heating pulse for the power device to be detected, so that the junction temperature of the power device to be detected is increased from the preset minimum junction temperature to the preset maximum junction temperature . During , the load current drops to 0, stops heating the power device to be detected, and dissipates heat from the power device to be detected, and obtains the first current junction temperature of the power device to be detected at the next moment after ends, so that the junction temperature of the power device to be detected drops from the preset maximum junction temperature to the first current junction temperature . During , the load current is increased to to provide the second heating pulse for the power device to be detected, so that the junction temperature of the power device to be detected rises again, from the first current junction temperature to the second current junction temperature, and obtains the second current junction temperature of the power device to be detected at the next moment after . During , the load current drops to 0, causing the power device to be detected to naturally dissipate heat to the preset minimum junction temperature . Among them, the period corresponds to the heating time of the first heating pulse, the period corresponds to the heat dissipation time after the first heating pulse stops, the period corresponds to the heating time of the second heating pulse, the period corresponds to the heat dissipation time after the second heating pulse stops.

[0085] Combined with Figure 3 and Figure 4, it can be understood that according to the temperature change curve of the power device to be detected, the power device to be detected after natural heat dissipation is reheated by the second heating pulse, which is equivalent to reproducing the temperature rise process of the target encapsulation film layer. Therefore, by obtaining the first current junction temperature of the power device to be detected at the next moment when the first heating pulse heating is stopped and the second current junction temperature of the power device to be detected at the next moment when the second heating pulse heating is stopped, it is equivalent to extracting the temperature at the start and end points of the temperature change process of the target encapsulation film layer, thereby improving the accuracy of temperature extraction and avoiding monitoring the temperature change of the entire encapsulation structure, which makes it difficult to judge the temperature change of the target encapsulation film layer.

[0086] Step S160: Determine the current thermal resistance of the target encapsulation film layer according to the first current junction temperature, the second current junction temperature, and the second heating pulse power.

[0087] Exemplarily, it can be based on:

[0088] (3)

[0089] Determine the current thermal resistance of the target encapsulation film layer .

[0090] Step S170: Judge the aging state of the target encapsulation film layer according to the current thermal resistance and the preset thermal resistance of the target encapsulation film layer.

[0091] Exemplarily, it can be judged that the target encapsulation film layer is in an aging state when the current thermal resistance is greater than the preset thermal resistance.

[0092] It should be noted that the cooling process of the encapsulation structure is the reverse process of the heating process, and the temperature-sensitive electrical parameter method has higher accuracy during the cooling process. Therefore, in the embodiments of the present application, the first current junction temperature and the second current junction temperature are extracted after turning off the first heating pulse and the second heating pulse, which can further improve the accuracy of the first current junction temperature and the second current junction temperature, and further improve the accuracy of the aging monitoring result.

[0093] The power device package aging monitoring method provided by the embodiment of the present application first heats the junction temperature of the power device to be detected to the preset maximum junction temperature by a first heating pulse and then stops heating, forming a first-order zero-state thermal response inside the package structure, constructing the complete thermal path information inside the package structure, so that heat can reach different film layers in the package structure at different times. Then, the power device to be detected is cooled, and the cooling time of the power device to be detected is equal to the cooling time. According to the heat transfer relationship of each film layer in the package structure of the power device to be detected, after the natural cooling of the target package film layer in the package structure and the auxiliary package film layer between the target package film layer and the heat source is completed, the first current junction temperature after the natural cooling of the target package film layer is obtained. Further, by adjusting the heating pulse to a second heating pulse and reheating the power device package structure, the auxiliary package film layer between the target package film layer and the heat source is reheated to the state before natural cooling, changing the thermal transient process of the target package film layer, restoring the thermal information of the target package film layer, and obtaining the second current junction temperature of the target package film layer at this time. According to the difference between the first current junction temperature and the second current junction temperature, the change in the junction temperature of the power device before and after cooling of the target package film layer can be determined, so that the current thermal resistance of the target package film layer can be determined, which is convenient for judging whether the target package film layer is aged based on the difference between the current thermal resistance of the target package film layer and the preset thermal resistance. Therefore, without disassembling and assembling the package structure, it is possible to monitor a specific target package film layer in the power device package structure, judge the aging condition of the entire package structure based on the aging condition of a single target package film layer, so that thermal characteristic parameters can be identified in the thermal characteristic test of the power device, and the accuracy and reliability of the aging monitoring method can be improved in the aging test of the power device package structure. The aging problem of the power device package structure can be located, the practicability and effectiveness of the aging monitoring method can be improved, and the monitoring quality and monitoring efficiency of aging monitoring can be improved.

[0094] In some feasible embodiments, before the step of heating the power device to be detected according to the second heating pulse, it further includes: determining the thermal resistance values and heat capacity values of the auxiliary package film layer and the target package film layer according to the thermal conductivity, specific heat capacity, density, and film layer thickness of the auxiliary package film layer and the target package film layer; determining a first thermal time constant according to the thermal resistance values and heat capacity values of the auxiliary package film layer and the target package film layer, where the first thermal time constant is the sum of the products of the thermal resistance values and heat capacity values of the corresponding film layers in the auxiliary package film layer and the target package film layer, and the second thermal time constant is the sum of the products of the thermal resistance values and heat capacity values of the corresponding film layers in all the auxiliary package film layers.

[0095] Exemplarily, it can be through:

[0096] (4)

[0097] Determine the thermal resistance between the auxiliary encapsulation film layer and the target encapsulation film layer , by:

[0098] (5)

[0099] Determine the heat capacity between the auxiliary encapsulation film layer and the target encapsulation film layer , where λ is the thermal conductivity of the material; is the specific heat capacity of the material; is the density of the material; is the thickness of the th layer structure in the device package, is the effective heat dissipation area of the th layer structure in the device package.

[0100] Exemplarily, it can be through:

[0101] (6)

[0102] Determine the thermal time constant between the auxiliary encapsulation film layer and the target encapsulation film layer . It can be understood that the thermal time constant is only related to the thermal conductivity, specific heat capacity, density and thickness of the materials of each film layer, and has nothing to do with the heat dissipation area.

[0103] The power device package aging monitoring method provided by the embodiments of the present application can predict the behavior of the package structure under different thermal conditions by determining the thermal time constant, so as to facilitate the restoration of the actual junction temperature of the target encapsulation film layer before and after secondary heating in the thermal transient analysis, which can further improve the accuracy of the first current junction temperature and the second current junction temperature, and improve the accuracy of the aging monitoring results.

[0104] In some feasible embodiments, when the power device to be detected is a welded device, the target encapsulation film layer includes a chip solder layer and a system solder layer; when the power device to be detected is a crimped device, the target encapsulation film layer includes a welding layer and a contact interface, where the contact interface includes the contact interface between the power chip and the metal heat dissipation layer.

[0105] It should be noted that in the package structure of the power device to be detected, the structural thermal resistance of the welding layer and the contact interface accounts for a relatively small proportion of the junction-to-case thermal resistance, and the change in the structural thermal resistance caused by the aging of the above two cannot cause the change in the junction-to-case thermal resistance to reach the aging criterion. Therefore, it is necessary to monitor the structural thermal resistance of the welding layer and the contact interface in real time to improve the accuracy and effectiveness of aging monitoring and reduce the positioning difficulty of the aging problem of the power device package structure. In addition, during the operation of the power device to be detected, the aging risk of the welding layer and the contact interface is relatively high. Therefore, taking the welding layer and the contact interface as the target encapsulation film layer can further improve the timeliness of aging monitoring.

[0106] In some feasible embodiments, the aging state of the target encapsulation film layer is determined according to the current thermal resistance and the preset thermal resistance of the target encapsulation film layer, including: when the current thermal resistance is greater than the preset thermal resistance, it is determined that the target encapsulation film layer is aged, where the preset thermal resistance is determined according to the initial thermal resistance of the target encapsulation film layer.

[0107] For the power device package aging monitoring method provided by the embodiments of the present application, when the current thermal resistance of the target encapsulation film layer is greater than the preset thermal resistance, it can be considered that the structural thermal resistance of the target encapsulation film layer changes significantly, and it is determined that the target encapsulation film layer is aged, thereby improving the accuracy and objectivity of the aging monitoring result, reducing the positioning difficulty of the aging problem of the power device package structure, and improving the monitoring quality and monitoring efficiency.

[0108] In some feasible embodiments, the heat dissipation time is equal to three times the first thermal time constant; the heating time of the second heating pulse is equal to three times the second thermal time constant.

[0109] It should be noted that when monitoring the heat transfer process of the power device package structure to be detected, multiple film layers in the package structure can be approximately equivalent to multiple closely stacked thin plates. As Figure 5 shown, a heat source with a constant power and uniform distribution is applied to one surface of the thin plate, the four sides of the thin plate are adiabatic, and at the same time, the thin plate is arranged on the surface of an ideal heat sink, so that the heat source and the heat dissipation surface are two opposite surfaces in the heat transfer direction of the thin plate. Therefore, it can be obtained by:

[0110] (7)

[0111] Determine the first-order zero-state response of the thin plate, where T(t) is the temperature of the heat source of the thin plate at time t, is the power of the heating pulse, is the thermal resistance of the thin plate, and τ is the thermal time constant of the thin plate. As Figure 6 shown, when t = 3τ, , therefore, in the case of heating the thin plate by the heating pulse , the temperature of the thin plate after a heating duration three times the thermal time constant is equal to the temperature of the thin plate when it reaches thermal steady state.

[0112] In the power device package aging monitoring method provided by the embodiment of the present application, when the heat dissipation time is equal to three times the first thermal time constant and the heating time of the second heating pulse is equal to three times the second thermal time constant, the auxiliary package film layer and the target package film layer can be fully heated, so that each package film layer can approximately reach the thermal steady state, thereby improving the accuracy and objectivity of the first current junction temperature and the second current junction temperature, further improving the accuracy of the aging monitoring result, shortening the heating time of the first heating pulse and the second heating pulse, improving the monitoring speed of the aging monitoring, improving the timeliness of the aging monitoring, and improving the monitoring efficiency and monitoring quality.

[0113] In some feasible embodiments, the power of the second heating pulse is equal to the product of the power of the first heating pulse and the target coefficient, where the target coefficient is equal to the ratio of the first thermal time constant to the total thermal time constant of the package structure.

[0114] In the power device package aging monitoring method provided by the embodiment of the present application, the target coefficient is determined by the ratio of the first thermal time constant to the total thermal time constant of the package structure, and further the power of the second heating pulse is determined by the product of the target coefficient and the power of the first heating pulse. Based on the heat transfer direction of each package film layer in the package structure, the relative value of the heat absorbed by the auxiliary package film layer and the target package film layer relative to the entire package structure under thermal steady state can be determined, so that the temperature rise process of the target package film layer can be reproduced during the second heating, improving the accuracy of the second heating pulse, further improving the accuracy of the second current junction temperature, and thus improving the accuracy of the aging monitoring result.

[0115] In some feasible embodiments, when the power device to be detected is a double-sided heat dissipation device, the power device to be detected includes a power chip and two symmetrically arranged package structures, and the power chip is located between the two package structures. Heating the power device to be detected according to the first heating pulse includes: applying a first step current to the power chip at the center of the power device to be detected, so that the power chip heats the package structure according to the first heating pulse, causing the junction temperature of the power device to be detected to rise to a preset maximum junction temperature.

[0116] In some feasible embodiments, when the power device to be detected is a double-sided heat dissipation device, heating the power device to be detected according to the second heating pulse includes: applying a second step current to the power chip at the center of the power device to be detected, so that the power chip heats the package structure according to the second heating pulse, where the heating time of the power device to be detected is equal to the heating time of the second heating pulse.

[0117] In some feasible embodiments, when the power device to be detected is a double-sided heat dissipation device, determining the current thermal resistance of the target encapsulation film layer according to the first current junction temperature, the second current junction temperature, and the second heating pulse power includes: determining the first current thermal resistance of the target encapsulation film layer in the encapsulation structure on one side of the power chip according to the first current junction temperature, the second current junction temperature, and the heating power transferred by the second heating pulse to the encapsulation structure on one side of the power chip; determining the second current thermal resistance of the target encapsulation film layer in the encapsulation structure on the other side of the power chip according to the first current junction temperature, the second current junction temperature, and the heating power transferred by the second heating pulse to the encapsulation structure on the other side of the power chip; and determining the current thermal resistance of the target encapsulation film layer according to the first current thermal resistance and the second current thermal resistance.

[0118] It should be noted that, as Figure 7 shown, when the power device to be detected is a double-sided heat dissipation device, encapsulation structures with the same structure are symmetrically arranged on both sides of the chip. Among them, the auxiliary encapsulation film layer includes the chip, the contact interface, the cathode molybdenum sheet, etc., and the target encapsulation film layer includes the cathode substrate.

[0119] When the power device to be detected is a double-sided heat dissipation device, by applying a step current to the power chip, the power chip can generate heat flow and transfer heat to the encapsulation structures on both sides simultaneously in opposite directions. Therefore, at this time, the target encapsulation film layer includes the same type of film layer at the same position in the two encapsulation structures, so the two target encapsulation film layers can be equivalent to two sub-target encapsulation film layers connected in parallel. Thus, it can be through:

[0120] (8)

[0121] (9)

[0122] (10)

[0123] (11)

[0124] Determine the current thermal resistance of the target encapsulation film layer in the double-sided heat dissipation device. Among them, is the heating power transferred by the second heating pulse to the encapsulation structure on one side of the power chip, is the heating power transferred by the second heating pulse to the encapsulation structure on the other side of the power chip, is the first current thermal resistance of the target encapsulation film layer in the encapsulation structure on one side of the chip; is the second current thermal resistance of the target encapsulation film layer in the encapsulation structure on the other side of the chip; and The current thermal resistance obtained after parallel connection.

[0125] It should be noted that in the actual aging monitoring process, the coupling of heat transfer on both sides of the power chip cannot be directly analyzed only through the junction temperature.

[0126] The power device package aging monitoring method provided by the embodiments of the present application can reduce the difficulty of heat transfer analysis of double-sided heat dissipation devices, improve the convenience and effectiveness of the aging monitoring method, and improve the monitoring quality and monitoring efficiency of aging monitoring by equating the current thermal resistance of the target package film layer on different sides of the power chip to two parallel structural thermal resistances to determine the actual thermal resistance of the target package film layer in the power device to be detected.

[0127] As Figure 8 shown, in the second aspect of the embodiments of the present application, a power device package aging monitoring circuit is provided, including: a monitoring circuit, a first pulse circuit, and a second pulse circuit. Among them, the monitoring circuit is used to be connected in parallel with the power device to be detected. The monitoring circuit is used to provide a monitoring current to obtain the junction temperature of the power device to be detected, and determine the current thermal resistance of the target package film layer in the power device to be detected according to the first current junction temperature and the second current junction temperature of the power device to be detected, so as to determine the aging state of the target package film layer according to the current thermal resistance; the first pulse circuit is connected in parallel with the monitoring circuit. The first pulse circuit includes a first pulse current source and a first switch S1. The first pulse current source and the first switch S1 are connected in series. The first pulse current source is used to provide a first heating pulse to heat the power device to be detected, and the first switch S1 is used to control the heating time of the first pulse current source to raise the junction temperature of the power device to be detected to a preset maximum junction temperature; the second pulse circuit is connected in parallel with the monitoring circuit. The second pulse circuit includes a second pulse current source and a second switch S2. The second pulse current source and the second switch S2 are connected in series. The second pulse current source is used to provide a second heating pulse to heat the power device to be detected, and the second switch S2 is used to control the heating time of the second pulse current source. The heating time of the second pulse current source is determined according to the second thermal time constant, and the second thermal time constant is equal to the sum of the thermal time constants of all the auxiliary package film layers of the power device to be detected. The auxiliary package film layers are located between the target package film layer and the heat source in contact with the power device to be detected; the first switch S1 and the second switch S2 are conductively connected at intervals, and the conduction interval duration of the first switch S1 and the second switch S2 is equal to the heat dissipation time.

[0128] The power device package aging monitoring circuit provided by the embodiment of the present application first heats the junction temperature of the power device to be detected to the preset maximum junction temperature by a first heating pulse and then stops heating, forming a first-order zero-state thermal response inside the package structure, constructing the complete thermal path information inside the package structure, so that heat can reach different film layers in the package structure at different times. Then, the power device to be detected is cooled, so that the cooling time of the power device to be detected is equal to the cooling time. According to the heat transfer relationship of each film layer in the package structure of the power device to be detected, after the natural cooling of the target package film layer in the package structure and the auxiliary package film layer between the target package film layer and the heat source is completed, the first current junction temperature after the natural cooling of the target package film layer is obtained. Further, by adjusting the heating pulse to a second heating pulse and reheating the power device package structure, the auxiliary package film layer between the target package film layer and the heat source is reheated to the state before natural cooling, changing the thermal transient process of the target package film layer, restoring the thermal information of the target package film layer, and obtaining the second current junction temperature of the target package film layer at this time. According to the difference between the first current junction temperature and the second current junction temperature, the change in the junction temperature of the power device before and after cooling of the target package film layer can be determined, so that the current thermal resistance of the target package film layer can be determined, which is convenient for judging whether the target package film layer is aged based on the difference between the current thermal resistance of the target package film layer and the preset thermal resistance. Therefore, without disassembling and assembling the package structure, the monitoring of a specific target package film layer in the power device package structure can be realized, and the aging condition of the whole package structure can be judged by the aging condition of a single target package film layer. Thus, thermal characteristic parameter identification can be carried out in the thermal characteristic test of the power device, the accuracy and reliability of the aging monitoring method can be improved in the aging test of the power device package structure, the aging problem of the power device package structure can be located, the practicability and effectiveness of the aging monitoring method can be improved, and the monitoring quality and monitoring efficiency of the aging monitoring can be improved.

[0129] As Figure 9 shown, in the third aspect of the embodiment of the present application, a driving method for a power device package aging monitoring circuit is provided, which is used to drive the power device package aging monitoring circuit as described in the second aspect above. The driving method of the power device package aging monitoring circuit includes:

[0130] Step S210: Provide a monitoring power supply to the power device to be detected through a monitoring circuit to obtain the junction temperature of the power device to be detected.

[0131] Step S220: Close the first switch in the first pulse circuit, turn on the first pulse current source in the first pulse circuit, and turn off the second switch in the second pulse circuit, so that the first pulse current source heats the power device to be detected according to the first heating pulse, and raises the junction temperature of the power device to be detected to the preset maximum junction temperature.

[0132] Step S230: Turn off the first switch and the second switch, and dissipate heat from the power device to be detected whose current junction temperature is equal to the preset maximum junction temperature, where the heat dissipation duration of the power device to be detected is equal to the heat dissipation time.

[0133] Step S240: Provide a monitoring power supply to the power device to be detected through the monitoring circuit to obtain the first current junction temperature of the power device to be detected.

[0134] Step S250: Close the second switch and turn on the second pulse current source in the second pulse circuit, so that the second pulse current source heats the power device to be detected according to the second heating pulse, where the heating time of the power device to be detected is equal to the heating time of the second heating pulse.

[0135] Step S260: Provide a monitoring power supply to the power device to be detected through the monitoring circuit to obtain the second current junction temperature of the power device to be detected, determine the current thermal resistance of the target encapsulation film layer according to the first current junction temperature, the second current junction temperature and the second heating pulse power, and judge the aging state of the target encapsulation film layer according to the current thermal resistance and the preset thermal resistance of the target encapsulation film layer.

[0136] The driving method of the power device package aging monitoring circuit provided by the embodiment of the present application first heats the junction temperature of the power device to be detected to the preset maximum junction temperature by a first heating pulse and then stops heating, forming a first-order zero-state thermal response inside the package structure, constructing the complete thermal path information inside the package structure, so that heat can reach different film layers in the package structure at different times. Then, the power device to be detected is cooled, and the cooling time of the power device to be detected is equal to the cooling time. According to the heat transfer relationship of each film layer in the package structure of the power device to be detected, after the target package film layer in the package structure and the auxiliary package film layer between the target package film layer and the heat source complete natural cooling, the first current junction temperature after the target package film layer completes natural cooling is obtained. Further, by adjusting the heating pulse to a second heating pulse and reheating the power device package structure, the auxiliary package film layer between the target package film layer and the heat source is reheated to the state before natural cooling, changing the thermal transient process of the target package film layer, restoring the thermal information of the target package film layer, and obtaining the second current junction temperature of the target package film layer at this time. According to the difference between the first current junction temperature and the second current junction temperature, the change in the junction temperature of the power device before and after cooling of the target package film layer can be determined, so that the current thermal resistance of the target package film layer can be determined, which is convenient for judging whether the target package film layer is aged based on the difference between the current thermal resistance of the target package film layer and the preset thermal resistance. Therefore, without disassembling and assembling the package structure, the monitoring of a specific target package film layer in the power device package structure can be realized, and the aging condition of the overall package structure can be judged by the aging condition of a single target package film layer. Thus, thermal characteristic parameter identification can be carried out in the power device thermal characteristic test, the accuracy and reliability of the aging monitoring method can be improved in the power device package structure aging test, the aging problem of the power device package structure can be located, the practicability and effectiveness of the aging monitoring method can be improved, and the monitoring quality and monitoring efficiency of aging monitoring can be improved.

[0137] Such as Figure 10As shown in the figure, in the fourth aspect of the embodiments of the present application, a power device package aging monitoring device is provided, including: a first heating module 10, a heat dissipation module 20, a first temperature measurement module 30, a second heating module 40, a second temperature measurement module 50, a first determination module 60, and a second determination module 70. Among them, the first heating module 10 is configured to heat the power device to be detected according to a first heating pulse, so that the junction temperature of the power device to be detected rises to a preset maximum junction temperature; the heat dissipation module 20 is configured to dissipate heat from the power device to be detected whose current junction temperature is equal to the preset maximum junction temperature, where the heat dissipation time of the power device to be detected is determined according to a first thermal time constant, and the first thermal time constant is equal to the sum of the thermal time constants of the auxiliary package film layer and the target package film layer. The package structure of the power device to be detected includes an auxiliary package film layer and a target package film layer, and the auxiliary package film layer is located between the target package film layer and the heat source in contact with the power device to be detected; the first temperature measurement module 30 is configured to obtain the first current junction temperature of the power device to be detected; the second heating module 40 is configured to heat the power device to be detected according to a second heating pulse, where the heating time of the second heating pulse is determined according to a second thermal time constant, and the second thermal time constant is equal to the sum of the thermal time constants of all the auxiliary package film layers, and the second heating pulse power is determined according to the first heating pulse power, the first thermal time constant, and the second thermal time constant; the second temperature measurement module 50 is configured to obtain the second current junction temperature of the power device to be detected; the first determination module 60 is configured to determine the current thermal resistance of the target package film layer according to the first current junction temperature, the second current junction temperature, and the second heating pulse power; the second determination module 70 is configured to judge the aging state of the target package film layer according to the current thermal resistance and the preset thermal resistance of the target package film layer.

[0138] The power device package aging monitoring device provided by the embodiment of the present application first heats the junction temperature of the power device to be detected to the preset maximum junction temperature by a first heating pulse and then stops heating, forming a first-order zero-state thermal response inside the package structure, constructing the complete thermal path information inside the package structure, so that heat can reach different film layers in the package structure at different times. Then, the power device to be detected is cooled, and the cooling time of the power device to be detected is equal to the cooling time. According to the heat transfer relationship of each film layer in the package structure of the power device to be detected, after the natural cooling of the target package film layer in the package structure and the auxiliary package film layer between the target package film layer and the heat source is completed, the first current junction temperature after the natural cooling of the target package film layer is obtained. Further, by adjusting the heating pulse to a second heating pulse and heating the power device package structure for the heating time of the second heating pulse, the auxiliary package film layer between the target package film layer and the heat source is reheated to the state before natural cooling, changing the thermal transient process of the target package film layer, restoring the thermal information of the target package film layer, and obtaining the second current junction temperature of the target package film layer at this time. According to the difference between the first current junction temperature and the second current junction temperature, the change in the junction temperature of the power device before and after cooling of the target package film layer can be determined, so that the current thermal resistance of the target package film layer can be determined, which is convenient for judging whether the target package film layer is aged based on the difference between the current thermal resistance of the target package film layer and the preset thermal resistance. Therefore, without disassembling and assembling the package structure, the monitoring of a specific target package film layer in the power device package structure can be realized, and the aging condition of the whole package structure can be judged by the aging condition of a single target package film layer, so that the thermal characteristic parameters can be identified in the thermal characteristic test of the power device, and the accuracy and reliability of the aging monitoring method can be improved in the aging test of the power device package structure. The aging problem of the power device package structure can be located, the practicability and effectiveness of the aging monitoring method can be improved, and the monitoring quality and monitoring efficiency of the aging monitoring can be improved.

[0139] It should be understood that although the steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear indication in this article, the execution of these steps has no strict order limit, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be executed alternately or alternately with at least a part of other steps or steps or stages in other steps.

[0140] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0141] The above-described embodiments merely represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the patent scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.

Claims

1. A power device package aging monitoring method, characterized in that: include: heating the power device to be detected according to the first heating pulse, so that the junction temperature of the power device to be detected increases to a preset maximum junction temperature; dissipating heat for the power device to be detected whose current junction temperature is equal to the preset maximum junction temperature, wherein the heat dissipation time of the power device to be detected is determined according to a first thermal time constant, the first thermal time constant is equal to the sum of thermal time constants of an auxiliary packaging film layer and a target packaging film layer, the packaging structure of the power device to be detected comprises the auxiliary packaging film layer and the target packaging film layer, and the auxiliary packaging film layer is located between the target packaging film layer and a heat source in contact with the power device to be detected; Acquire a first current junction temperature of the power device to be detected; Heating the power device to be detected according to a second heating pulse, wherein the heating time of the second heating pulse is determined according to a second thermal time constant, the second thermal time constant is equal to the sum of the thermal time constants of all the auxiliary packaging film layers, and the second heating pulse power is determined according to the first heating pulse power, the first thermal time constant and the second thermal time constant; Acquire a second current junction temperature of the power device to be detected; Determine the current thermal resistance of the target packaging film layer according to the first current junction temperature, the second current junction temperature and the second heating pulse power; The aging state of the target packaging film layer is determined according to the current thermal resistance and the preset thermal resistance of the target packaging film layer.

2. The power device package aging monitoring method according to claim 1, characterized in that: Before the step of heating the power device to be detected according to the second heating pulse, the method further includes: Determining the thermal resistance and thermal capacity of the auxiliary packaging film layer and the target packaging film layer according to the thermal conductivity, specific heat capacity, density and film thickness of the auxiliary packaging film layer and the target packaging film layer; The first thermal time constant is determined according to the thermal resistance and thermal capacitance of the auxiliary packaging film layer and the target packaging film layer, wherein the first thermal time constant is the sum of the products of the thermal resistance and thermal capacitance of the corresponding film layers in the auxiliary packaging film layer and the target packaging film layer, and the second thermal time constant is the sum of the products of the thermal resistance and thermal capacitance of the corresponding film layers in all the auxiliary packaging film layers.

3. The power device package aging monitoring method according to claim 1, characterized in that: In the case where the power device to be detected is a soldering type device, the target packaging film layer includes a chip solder layer and a system solder layer; In the case where the power device to be inspected is a compression-type device, the target packaging film layer includes a welding layer and a contact interface, wherein the contact interface includes a contact interface between a power chip and a metal heat dissipation layer.

4. The power device package aging monitoring method according to claim 1, characterized in that: The step of judging the aging state of the target packaging film layer according to the current thermal resistance and the preset thermal resistance of the target packaging film layer includes: When the current thermal resistance is greater than the preset thermal resistance, it is determined that the target packaging film layer is aged, wherein the preset thermal resistance is determined according to the initial thermal resistance of the target packaging film layer.

5. The power device package aging monitoring method according to claim 1, characterized in that: The heat dissipation time is equal to three times of the first thermal time constant; The heating time of the second heating pulse is equal to three times the second thermal time constant.

6. The power device package aging monitoring method according to claim 1, characterized in that: The second heating pulse power is equal to the product of the first heating pulse power and a target coefficient, wherein the target coefficient is equal to a ratio of the first thermal time constant to a total thermal time constant of the packaging structure.

7. The power device package aging monitoring method according to claim 1, characterized in that: In the case where the power device to be detected is a double-sided heat dissipation device, the power device to be detected includes a power chip and two symmetrically arranged packaging structures, and the power chip is located between the two packaging structures; The step of heating the power device to be detected according to the first heating pulse comprises: Applying a first step current to the power chip at the center of the power device to be detected, so that the power chip heats the packaging structure according to the first heating pulse, so that the junction temperature of the power device to be detected rises to the preset maximum junction temperature; The step of heating the power device to be detected according to the second heating pulse comprises: Applying a second step current to the power chip at the center of the power device to be detected, so that the power chip heats the packaging structure according to the second heating pulse; The determining the current thermal resistance of the target packaging film layer according to the first current junction temperature, the second current junction temperature and the second heating pulse power comprises: Determine a first current thermal resistance of the target packaging film layer in the packaging structure located on one side of the power chip according to the first current junction temperature, the second current junction temperature, and the heating power transmitted by the second heating pulse to the packaging structure located on one side of the power chip; Determine a second current thermal resistance of the target packaging film layer in the packaging structure located on the other side of the power chip according to the first current junction temperature, the second current junction temperature, and the heating power transmitted by the second heating pulse to the packaging structure located on the other side of the power chip; The current thermal resistance of the target packaging film layer is determined according to the first current thermal resistance and the second current thermal resistance.

8. A power device package aging monitoring circuit, characterized in that: include: A monitoring circuit, wherein the monitoring circuit is connected in parallel with the power device to be detected, and the monitoring circuit is used to provide a monitoring current to obtain the junction temperature of the power device to be detected, and determine the current thermal resistance of the target packaging film layer in the power device to be detected according to the first current junction temperature and the second current junction temperature of the power device to be detected, so as to determine the aging state of the target packaging film layer of the power device to be detected according to the current thermal resistance; a first pulse circuit, connected in parallel with the monitoring circuit, the first pulse circuit comprising a first pulse current source and a first switch, the first pulse current source and the first switch being connected in series, the first pulse current source being used to provide a first heating pulse to heat the power device to be detected, and the first switch being used to control a heating time of the first pulse current source to increase a junction temperature of the power device to be detected to a preset maximum junction temperature; a second pulse circuit, connected in parallel with the monitoring circuit, the second pulse circuit comprising a second pulse current source and a second switch, the second pulse current source and the second switch being connected in series, the second pulse current source being used to provide a second heating pulse to heat the power device to be detected, the second switch being used to control a heating time of the second pulse current source, the heating time of the second pulse current source being determined according to a second thermal time constant, the second thermal time constant being equal to the sum of thermal time constants of all auxiliary packaging film layers of the power device to be detected, the auxiliary packaging film layer being located between the target packaging film layer and a heat source in contact with the power device to be detected; The first switch and the second switch are turned on at intervals, and the duration of the turn-on interval between the first switch and the second switch is equal to the heat dissipation time.

9. A driving method for a power device package aging monitoring circuit, characterized in that: Used to drive the power device package aging monitoring circuit as claimed in claim 8, the driving method of the power device package aging monitoring circuit comprising: Providing a monitoring power supply to the power device to be detected through a monitoring loop to obtain the junction temperature of the power device to be detected; Closing a first switch in a first pulse loop, turning on a first pulse current source in the first pulse loop, and turning off a second switch in a second pulse loop, so that the first pulse current source heats the power device to be detected according to a first heating pulse, so that the junction temperature of the power device to be detected is increased to a preset maximum junction temperature; Turning off the first switch and the second switch to dissipate heat for the power device to be detected whose current junction temperature is equal to the preset maximum junction temperature, wherein the heat dissipation duration of the power device to be detected is equal to the heat dissipation time; Providing a monitoring power supply to the power device to be detected through a monitoring loop to obtain a first current junction temperature of the power device to be detected; Closing the second switch and turning on the second pulse current source in the second pulse loop, so that the second pulse current source heats the power device to be detected according to the second heating pulse, wherein the heating time of the power device to be detected is equal to the heating time of the second heating pulse; A monitoring power supply is provided to the power device to be detected through the monitoring circuit to obtain the second current junction temperature of the power device to be detected, and the current thermal resistance of the target packaging film layer is determined according to the first current junction temperature, the second current junction temperature and the second heating pulse power, and the aging state of the target packaging film layer is judged according to the current thermal resistance and the preset thermal resistance of the target packaging film layer.

10. A power device package aging monitoring device, characterized in that: include: A first heating module is used to heat the power device to be detected according to the first heating pulse, so that the junction temperature of the power device to be detected is increased to a preset maximum junction temperature; A heat dissipation module, used for dissipating heat for the power device to be detected whose current junction temperature is equal to the preset maximum junction temperature, wherein the heat dissipation time of the power device to be detected is determined according to a first thermal time constant, the first thermal time constant is equal to the sum of thermal time constants of the auxiliary packaging film layer and the target packaging film layer, the packaging structure of the power device to be detected includes the auxiliary packaging film layer and the target packaging film layer, and the auxiliary packaging film layer is located between the target packaging film layer and the heat source in contact with the power device to be detected; A first temperature measurement module, used for obtaining a first current junction temperature of the power device to be detected; a second heating module, used for heating the power device to be detected according to a second heating pulse, wherein the heating time of the second heating pulse is determined according to a second thermal time constant, the second thermal time constant is equal to the sum of the thermal time constants of all the auxiliary packaging film layers, and the second heating pulse power is determined according to the first heating pulse power, the first thermal time constant and the second thermal time constant; A second temperature measurement module, used for obtaining a second current junction temperature of the power device to be detected; A first determination module, configured to determine a current thermal resistance of the target packaging film layer according to the first current junction temperature, the second current junction temperature, and the second heating pulse power; The second determining module is used to determine the aging state of the target packaging film layer according to the current thermal resistance and the preset thermal resistance of the target packaging film layer.

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