Junction temperature test system and method

Abstract

The application provides a junction temperature test system and method, comprising a first current unit, a second current unit, an operation unit and a control unit. The first current unit is used for outputting a first current with a surge current waveform. The control unit is used for turning on the electrical connection between the first current unit and a device under test at a first time point when the first current unit outputs the first current, and turning off the electrical connection between the first current unit and the device under test at a second time point when the first current unit outputs the first current; wherein the second time point is after the first time point. The second current unit is used for outputting a second current to the device under test. The operation unit is used for acquiring the voltage of the device under test when the electrical connection between the first current unit and the device under test is turned off, and calculating the junction temperature of the device under test according to the voltage of the device under test. The embodiment of the application can accurately measure the maximum junction temperature of the device, and can also realize the junction temperature measurement in the variation process of the surge waveform.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of testing, in particular to a junction temperature testing system and method. BACKGROUND

[0002] Surge testing is a method for checking the limit performance of rectifier diodes, which can test the resistance of products to surge current. Generally, the actual operating junction temperature of a device during a surge can be an important parameter for quantifying package aging and device aging.

[0003] At present, the existing surge testing system can test the junction temperature after the end of the surge, but the surge testing system cannot accurately measure the maximum junction temperature of the device, and cannot measure the junction temperature during the change process of the surge waveform. SUMMARY

[0004] Therefore, the present application provides a junction temperature testing system and method, which can accurately measure the maximum junction temperature of the device, and can also measure the junction temperature during the change process of the surge waveform.

[0005] In a first aspect, an embodiment of the present application provides a junction temperature testing system, comprising a first current unit, a second current unit, an operation unit and a control unit. The first current unit is configured to output a first current with a surge current waveform. The control unit is electrically connected between the first current unit and a device under test, and is configured to: at a first time point when the first current unit outputs the first current, turn on the electrical connection between the first current unit and the device under test; at a second time point when the first current unit outputs the first current, turn off the electrical connection between the first current unit and the device under test. The control unit is further configured to determine whether the time between the first time point and the second time point reaches a preset time. If the time between the first time point and the second time point does not reach the preset time, the control unit is further configured to: at the first time point when the first current unit outputs the first current, turn on the electrical connection between the first current unit and the device under test; at a third time point when the first current unit outputs the first current, turn off the electrical connection between the first current unit and the device under test; and the second current unit is configured to output a second current to the device under test. The operation unit is configured to obtain the voltage of the device under test when the electrical connection between the first current unit and the device under test is turned off, and calculate the junction temperature of the device under test according to the voltage of the device under test.

[0006] By using the embodiment of the present application, the maximum junction temperature of the device can be accurately measured, and the junction temperature during the change process of the surge waveform can also be measured. The junction temperature testing system and method of the embodiment of the present application can reduce the development cost of the testing system and improve the testing efficiency.

[0007] In a possible design, the control unit is further configured to determine whether a time between the first time point and the third time point reaches a preset time, and if the time between the first time point and the third time point does not reach the preset time, the control unit is configured to turn on an electrical connection between the first current unit and the device under test at the first time point at which the first current unit outputs the first current, and turn off the electrical connection between the first current unit and the device under test at the i th time point at which the first current unit outputs the first current, where i is equal to 4, 5, 6,..., n, and a time between the i th time point and the (i-1) th time point is equal to a time between the second time point and the third time point. With this design, the maximum junction temperature of the device can be accurately measured, and the junction temperature measurement during the variation process in the surge waveform can also be implemented.

[0008] In a possible design, the junction temperature test system further includes a sampling unit, where the sampling unit includes a current sampling module and a voltage sampling module, and the current sampling module is configured to collect a current of the device under test, and the voltage sampling module is configured to collect a voltage of the device under test. Based on this design, the voltage and current information of the device under test can be collected, and the voltage information can be fed back to the operation unit, so as to obtain the junction temperature of the device under test.

[0009] In a possible design, when the control unit turns off the electrical connection between the first current unit and the device under test, the current sampling unit samples the second current, and outputs a trigger signal to the voltage sampling module, the voltage sampling module samples the voltage of the device under test, and transmits the sampled voltage to the operation unit.

[0010] In a possible design, the control unit includes a first switch module, the first switch module is electrically connected between the first current unit and the device under test, and the first switch module is configured to turn on or turn off the electrical connection between the first current unit and the device under test. Based on this design, the control unit can control the connection state between the first current unit and the device under test.

[0011] In a possible design, the control unit further includes a second switch module, the second switch module is electrically connected between the first current unit and the first switch module, and the second switch module is closed when the first current unit outputs the first current and the first switch module is turned off. Based on this design, the remaining current in the first current can pass through the second switch module, and thus the remaining heat can be consumed.

[0012] In a possible design, the control unit further includes a control module, which is electrically connected to the first switch module and the second switch module, and is configured to control states of the first switch module and the second switch module.

[0013] In a second aspect, embodiments of the present application also provide a junction temperature testing method, which is applied to a junction temperature testing system, and the junction temperature testing system includes a first current unit, a second current unit, an operation unit and a control unit. The method includes: the first current unit outputs a first current with a surge current waveform; at a first time point when the first current unit outputs the first current, the electrical connection between the first current unit and the DUT is turned on; at a second time point when the first current unit outputs the first current, the electrical connection between the first current unit and the DUT is turned off; wherein the second time point is after the first time point; it is confirmed whether the time between the first time point and the second time point reaches a preset time; if the time between the first time point and the second time point does not reach the preset time, at the first time point when the first current unit outputs the first current, the electrical connection between the first current unit and the DUT is turned on; at a third time point when the first current unit outputs the first current, the electrical connection between the first current unit and the DUT is turned off; the second current unit is configured to output a second current to the DUT; when the electrical connection between the first current unit and the DUT is turned off, the voltage of the DUT is acquired, and the junction temperature of the DUT is calculated according to the voltage of the DUT. By using the embodiments of the present application, the maximum junction temperature of the device can be accurately measured, and the junction temperature measurement in the changing process of the surge waveform can also be realized. The junction temperature testing system and method of the embodiments of the present application can reduce the development cost of the testing system and improve the testing efficiency.

[0014] In a possible design, it is confirmed whether the time between the first time point and the third time point reaches the preset time; if the time between the first time point and the third time point does not reach the preset time, at the first time point when the first current unit outputs the first current, the electrical connection between the first current unit and the DUT is turned on; at an i-th time point when the first current unit outputs the first current, the electrical connection between the first current unit and the DUT is turned off; wherein i is equal to 4, 5, 6, … n; the time between the i-th time point and the (i-1)-th time point is equal to the time between the second time point and the third time point. By using such a design, the maximum junction temperature of the device can be accurately measured, and the junction temperature measurement in the changing process of the surge waveform can also be realized.

[0015] In one possible design, when the disconnection between the first current unit and the DUT is detected, the voltage of the DUT is sampled, and the junction temperature of the DUT is calculated according to the voltage of the DUT.

[0016] The junction temperature test system and method provided by the embodiments of the present application can accurately measure the maximum junction temperature of a device, and can also measure the junction temperature in the variation process of a surge waveform. The junction temperature test system and method of the embodiments of the present application can reduce the development cost of a test system and improve the test efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 FIG. 1 is a structural schematic diagram of a junction temperature test system according to an embodiment of the present application.

[0018] Figure 2 FIG. 2 is another structural schematic diagram of a junction temperature test system according to an embodiment of the present application.

[0019] Figure 3 FIG. 3 is another structural schematic diagram of a junction temperature test system according to an embodiment of the present application.

[0020] Figure 4 FIG. 4 is a schematic diagram of junction temperature measurement in a variation process of a surge current waveform according to an embodiment of the present application.

[0021] Figure 5 FIG. 5 is a flowchart of a junction temperature measurement method according to an embodiment of the present application.

[0022] MAIN ELEMENT SYMBOL EXPLANATION

[0023] Junction temperature test system 100 Inrush current unit 10 Control unit 20 Main circuit switch module 22 Free-wheeling circuit switch module 24 Control module 26 Sampling unit 30 Current sampling module 32 Voltage sampling module 34 Operation unit 40 Small current unit 50 Device under test 60

[0024] The following detailed description will further describe the present application in combination with the above-mentioned drawings. DETAILED DESCRIPTION

[0025] It should be noted that when one element is considered to be "connected" to another element, it can be directly connected to the other element or a middle element can exist at the same time. When one element is considered to be "arranged on" another element, it can be directly arranged on the other element or a middle element can exist at the same time.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terminology used in the description of the present application herein only for the purpose of describing specific embodiments of the present application, and is not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0027] Generally, the surge test can be a method for testing the limit performance of the rectifier diode, and can test the resistance of the product to the surge current. The actual junction temperature of the device during the surge process can be an important parameter for quantifying the aging of the package and the device.

[0028] It can be understood that the surge test system can test the junction temperature after the end of the surge, and the maximum junction temperature in the surge test can be near the current peak. How to accurately measure the maximum junction temperature of the device and establish it in the surge process is extremely important.

[0029] Therefore, an embodiment of the present application provides a junction temperature test system and method, which can accurately measure the maximum junction temperature of the device, and can also realize the junction temperature measurement in the changing process of the surge waveform. The junction temperature test system and method of the embodiment of the present application can also reduce the development cost of the test system and improve the test efficiency.

[0030] Referring to FIG. 1, Figure 1 , Figure 1 FIG. 1 shows a structure schematic diagram of a junction temperature test system 100 provided by an embodiment of the present application.

[0031] In the embodiment of the present application, the junction temperature test system 100 can include a surge current unit 10, a control unit 20, a sampling unit 30, an operation unit 40, a small current unit 50, and a device under test 60. The control unit 20 can be electrically connected between the surge current unit 10 and the device under test 60, the small current unit 50 can be electrically connected to the device under test 60, the operation unit 40 can be electrically connected to the sampling unit 30, and the sampling unit 30 can be electrically connected to the device under test 60. It can be understood that the surge current unit 10 can serve as a first current unit of the present application, and the small current unit 50 can serve as a second current unit of the present application. The device under test 60 can be a diode.

[0032] In the specific implementation process, the surge current unit 10 can output a first current, and the control unit 20 can be used to turn on or turn off the electrical connection between the surge current unit 10 and the device under test 60. The control unit 20 can control whether the first current passes through the device under test 60. For example, when the control unit 20 turns on the electrical connection between the surge current unit 10 and the device under test 60, the surge current unit 10 can output the first current to the device under test 60. The first current output by the surge current unit 10 can be a surge current, that is, the first current can be a current signal with a waveform, for example, the first current can be a surge current signal with a half-wave sine. Therefore, the surge current unit 10 in the embodiment of the present application can output a large current to the device under test 60.

[0033] The small current unit 50 can output a second current to the device under test 60, wherein the second current is a constant small current, and the small current can be between 10mA and 100mA. For example, the small current unit 50 can continuously output a small current of 20mA to the device under test 60. The sampling unit 30 can sample parameters of the device under test 60, for example, the sampling unit 30 can sample voltage and current of the device under test 60, and can transmit the collected parameters to the operation unit 40.

[0034] When the control unit 20 disconnects the electrical connection between the inrush current unit 10 and the device under test 60, the inrush current output by the inrush current unit 10 will not flow through the device under test 60, at this time, the second current output by the small current unit 50 flows through the device under test 60, the sampling unit 30 collects voltage data of the device under test 60, and transmits the collected voltage data to the operation unit 40, and the operation unit 40 can calculate the junction temperature value according to the collected voltage data.

[0035] Referring to FIG. 1, which shows a structural schematic diagram of a junction temperature test system 100 provided by another embodiment of the present application. Figure 2 Figure 2 Referring to FIG. 1, which shows a structural schematic diagram of a junction temperature test system 100 provided by another embodiment of the present application.

[0036] In this embodiment, the control unit 20 includes a main circuit switch module 22 and a freewheeling circuit switch module 24. The sampling unit 30 includes a current sampling module 32 and a voltage sampling module 34.

[0037] It can be understood that the inrush current unit 10 can be connected to the main circuit switch module 22 and the freewheeling circuit switch module 24. The main circuit switch module 22 can be connected to the device under test 60, and the small current unit 50 can be connected to the device under test 60.

[0038] In one possible implementation, the small current unit 50 can be electrically connected to both ends of the device under test 60, a first end of the main circuit switch module 22 can be electrically connected to a first end of the device under test 60, a second end of the main circuit switch module 22 can be electrically connected to a first end of the inrush current unit 10, a second end of the inrush current unit 10 can be electrically connected to a second end of the device under test 60, and the inrush current unit 10 can be connected in parallel with the freewheeling circuit switch module 24.

[0039] In one embodiment, the main circuit switch module 22 can include a first switch. When the first switch is turned on, the inrush current unit 10 can output an inrush current to the device under test 60.​

[0040] In the embodiment, when the main circuit switch module 22 is off, the freewheeling circuit switch module 24 is on, thus the residual current in the inrush current can flow through the freewheeling circuit switch module 24. It can be understood that in one possible implementation, the freewheeling circuit switch module 24 can include a second switch and a resistor. When the second switch is on, the residual current in the inrush current can pass through the resistor, and the residual heat can be consumed.

[0041] Referring to FIG. 1, a structure schematic diagram of a junction temperature test system 100 provided by another embodiment of the present application is shown. Figure 3 Figure 3 Referring to FIG. 1, a structure schematic diagram of a junction temperature test system 100 provided by another embodiment of the present application is shown.

[0042] Referring to FIG. 1, a structure schematic diagram of a junction temperature test system 100 provided by another embodiment of the present application is shown. Figure 2 The difference between the junction temperature test system shown in the embodiment and the junction temperature test system shown in FIG. 1 is that, as shown in FIG. 2, in the embodiment, the control unit 20 can further include a control module 26. The control module 26 can be connected to the main circuit switch module 22 and the freewheeling circuit switch module 24. The control module 26 can output signals to the main circuit switch module 22 and the freewheeling circuit switch module 24. For example, the control module 26 can output pulse width modulation (PWM) signals to the main circuit switch module 22 and the freewheeling circuit switch module 24, thus the states of the main circuit switch module 22 and the freewheeling circuit switch module 24 can be controlled. Figure 3

[0043] For example, the small current unit 50 outputs a small current of 10mA-100mA to the device under test 60, for example, the small current unit 50 outputs a current of 20mA to the device under test 60, the voltage sampling module 34 collects the voltage value V F of the device under test 60 and transmits the voltage value V F to the operation unit 40, and the operation unit 40 takes the voltage value V F as the standard V F value under the initial junction temperature 25℃. Assuming that the duration of the inrush current is T, as shown in FIG. 3, the operation unit 40 can calculate the junction temperature T Figure 4 ​​As shown, the duration of the inrush current can start from 4000us and end at 12000us. At the time tO (e.g. 4000us), the control module 26 can control the main circuit switch module 22 to be on and the freewheeling circuit switch module 24 to be off, and the inrush current unit 10 can output a sine half-wave inrush current to the device under test 60, and the small current unit 50 can output a small current of 10mA-100mA to the device under test 60. At the time tO+ax (e.g. 4500us) when the inrush current unit 10 outputs the inrush current, where x is less than T, the control module 26 can control the main circuit switch module 22 to be off and the freewheeling circuit switch module 24 to be on. At this time, the current sampling module 32 samples the current in the device under test 60 as the small current output by the small current unit 50, and can trigger the voltage sampling module 34 to transmit the collected voltage data 1 to the operation unit 40, and the operation unit 40 can convert the collected voltage data 1 into junction temperature 1.

[0044] After obtaining the junction temperature 1, the control module 26 confirms whether the time between the time tO and tO+ax reaches the preset time (e.g. time T). If the time between the time tO and tO+ax does not reach the time T, at the time tO (e.g. 4000us), the control module controls the main circuit switch module 22 to be on and the freewheeling circuit switch module 24 to be off, and at this time, the inrush current unit 10 and the small current unit 50 both start to output current to the device under test 60. At the time tO+(a+1)x (e.g. 5000us) when the inrush current unit 10 outputs the inrush current, the control module 26 controls the main circuit switch module 22 to be off and the freewheeling circuit switch module 24 to be on. At this time, the current sampling module 32 samples the current in the device under test 60 as the small current output by the small current unit 50, and can trigger the voltage sampling module 34 to transmit the collected voltage data 2 to the operation unit 40, and the operation unit 40 can convert the collected voltage data 2 into junction temperature 2.

[0045] After obtaining the junction temperature 2, the control module 26 confirms whether the time between the to time and the to+(a+1)x time reaches the preset time (for example, time T). If the time between the to time and the to+(a+1)x time does not reach the time T, the control module controls the main circuit switch module 22 to be turned on and the freewheeling circuit switch module 24 to be turned off at the to time (for example, 4000us), and at this time, the inrush current unit 10 and the small current unit 50 start to output current to the device under test 60. At the to+(a+2)x time (for example, 5500us), the control module 26 controls the main circuit switch module 22 to be turned off and the freewheeling circuit switch module 24 to be turned on. At this time, the current sampling module 32 samples the current in the device under test 60 as the small current output by the small current unit 50, and can trigger the voltage sampling module 34 to transmit the collected voltage data 3 to the operation unit 40, and the operation unit 40 can convert the collected voltage data 3 into the junction temperature 3. It can be understood that the time between the to time and the to+ax time is the same as the time between the to time and the to+(a+1)x time.

[0046] The control unit is also used to confirm whether the time between the to time and the to+(a+1)x time reaches the time T. If the time between the to time and the to+(a+1)x time does not reach the preset time, the control module 26 is used to turn on the electrical connection between the inrush current unit 10 and the device under test 60 at the to time when the inrush current unit 10 outputs current, and turn off the electrical connection between the inrush current unit 10 and the device under test 60 at the i time point when the inrush current unit outputs the first current. Wherein i is equal to 4, 5, 6, … n. As shown in the figure, the junction temperature test system 100 can repeat the above junction temperature measurement steps until the output time of the inrush current reaches the time T. Therefore, the implementation of the present application can obtain the junction temperature corresponding to multiple output times of the inrush current, so that the junction temperature measurement in the change process of the inrush waveform can be realized. Figure 4

[0047] The junction temperature test system of the present application can accurately measure the maximum junction temperature of the device, and can also realize the junction temperature measurement in the change process of the inrush waveform.

[0048] Please refer to Figure 5 , Figure 5 The flow chart of the junction temperature test method provided by an embodiment of the present application. The junction temperature test method can include the following steps:

[0049] Step S51: The small current unit outputs current to the device under test, and records the initial voltage value of the device at normal temperature. ​

[0050] by Figure 3 The junction temperature testing system 100 shown is used as an example for explanation. During junction temperature measurement, the small current unit 50 outputs a small current of 10mA to 100mA to the device under test 60, and the voltage sampling module 34 can acquire the voltage value V of the device under test 60. F and the voltage value V F The voltage value V is transmitted to the arithmetic unit 40, which then transmits it to the arithmetic unit 40. F As the standard V at an initial junction temperature of 25℃ F value.

[0051] Step S52: At time t0, turn on the main circuit switch module and turn off the freewheeling circuit switch module. The surge current unit and the small current unit output current to the device under test.

[0052] Assume the duration of the surge current output by the surge current unit 10 is T. At time t0, as... Figure 4 As shown, the duration of the surge current can start from 4000us. The control module can control the main circuit switch module 22 to be turned on and control the freewheeling circuit switch module 24 to be turned off. The surge current unit 10 can output a sinusoidal half-wave surge current to the device under test 60. Thus, the small current unit 50 outputs a small current of 10mA to 100mA to the device under test 60.

[0053] Step S53: At time t0+ax, turn on the freewheeling circuit switch module and turn off the main circuit switch module.

[0054] At the time t0+ax when the surge current unit 10 outputs the surge current, as Figure 4 As shown, the surge current duration can end at 4500µs. The control module 26 can control the main circuit switch module 22 to disconnect and control the freewheeling circuit switch module 24 to turn on.

[0055] Step S54: When the trigger current sampling module only collects the current output of the small current, the trigger voltage sampling module collects the voltage of the device under test and converts the voltage into junction temperature.

[0056] Since the surge current unit 10 is disconnected from the device under test 60, the current sampling module 32 samples the current in the device under test 60 as the small current output by the small current unit 50, and can trigger the voltage sampling module 34 to send the collected voltage data to the calculation unit 40. The calculation unit 40 can convert the collected voltage into a junction temperature of 1.

[0057] Step S55: confirming whether the value T is reached at the time t0+ax after the inrush current unit outputs current. If yes, go to step S56, otherwise return to step S52.

[0058] When the operation unit 40 obtains the junction temperature 1 of the inrush current at the time t0+ax, the steps S52 and S54 can be re-executed. At this time, a=a+1. For example, after obtaining the junction temperature 1, the control module 26 controls the main circuit switch module 22 to be turned on and the freewheeling circuit switch module 24 to be turned off from the time t0 (for example, 4000us), at this time, the inrush current unit 10 and the small current unit 50 both start to output current to the device under test 60. At the time t0+(a+1)x (for example, 5000us) when the inrush current unit 10 outputs inrush current, the control module 26 controls the main circuit switch module 22 to be turned off and the freewheeling circuit switch module 24 to be turned on. At this time, the current sampling module 32 samples the current in the device under test 60 to be the small current output by the small current unit 50, and the voltage sampling module 34 can be triggered to transmit the collected voltage data 2 to the operation unit 40, and the operation unit 40 can convert the collected voltage data 2 into the junction temperature 2.

[0059] Therefore, until the value T is reached at the time t0+ax after the inrush current unit outputs current, the junction temperature measurement in the whole inrush current waveform change process is completed.

[0060] Step S56: the operation unit calculates the junction temperature change graph of the inrush process and identifies the maximum junction temperature.

[0061] In the embodiment of the present application, the operation unit can record the junction temperature in the whole inrush waveform change process, and can identify the maximum junction temperature.

[0062] The junction temperature test system and method in the embodiment of the present application can accurately measure the maximum junction temperature of the device, and can also realize the junction temperature measurement in the inrush waveform change process.

[0063] The above is only a preferred embodiment of the present application, and is not any form of limitation on the present application. Although the preferred embodiment of the present application is disclosed as above, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical solution of the present application, and the equivalent embodiments with equivalent changes and modifications can be made. Any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present application, without departing from the technical solution of the present application, still belongs to the scope of the technical solution of the present application.

Claims

1. A junction temperature testing system, characterized in that, It includes a first current unit, a second current unit, an arithmetic unit, and a control unit; The first current unit is used to output a first current with a surge current waveform; The control unit is electrically connected between the first current unit and the device under test, and is used to: at a first time point when the first current unit outputs a first current, conduct the electrical connection between the first current unit and the device under test; at a second time point when the first current unit outputs a first current, disconnect the electrical connection between the first current unit and the device under test. The control unit is further configured to confirm whether the time between the first time point and the second time point has reached a preset time. If the time between the first time point and the second time point has not reached the preset time, the control unit is further configured to connect the electrical connection between the first current unit and the device under test at the first time point when the first current unit outputs the first current; and disconnect the electrical connection between the first current unit and the device under test at the third time point when the first current unit outputs the first current. The second current unit is used to output a second current to the device under test; The arithmetic unit is used to acquire the voltage of the device under test when the connection between the first current unit and the device under test is disconnected, and to calculate the junction temperature of the device under test based on the voltage of the device under test.

2. The junction temperature testing system as described in claim 1, characterized in that, The control unit is further configured to confirm whether the time between the first time point and the third time point has reached the preset time; if the time between the first time point and the third time point has not reached the preset time; The control unit is used to connect the electrical connection between the first current unit and the device under test at a first time point when the first current unit outputs the first current; and to disconnect the electrical connection between the first current unit and the device under test at the i-th time point when the first current unit outputs the first current. Where i equals 4, 5, 6, ... n; the time between the i-th time point and the (i-1)-th time point is equal to the time between the second time point and the third time point.

3. The junction temperature testing system as described in claim 1, characterized in that, The junction temperature testing system further includes a sampling unit, which includes a current sampling module and a voltage sampling module. The current sampling module is used to collect the current of the device under test, and the voltage sampling module is used to collect the voltage of the device under test.

4. The junction temperature testing system as described in claim 3, characterized in that, When the control unit disconnects the electrical connection between the first current unit and the device under test, the current sampling module samples the second current and outputs a trigger signal to the voltage sampling module. The voltage sampling module samples the voltage of the device under test and transmits the sampled voltage to the arithmetic unit.

5. The junction temperature testing system as described in any one of claims 1-4, characterized in that, The control unit includes a first switch module, which is electrically connected between the first current unit and the device under test. The first switch module is used to turn on or off the electrical connection between the first current unit and the device under test.

6. The junction temperature testing system as described in claim 5, characterized in that, The control unit further includes a second switch module, which is electrically connected to the first current unit and the first switch module; when the first current unit outputs the first current and the first switch module is turned off, the second switch module is closed.

7. The junction temperature testing system as described in claim 6, characterized in that, The control unit further includes a control module, which is electrically connected to the first switch module and the second switch module, and is used to control the state of the first switch module and the second switch module.

8. A junction temperature testing method, applied to a junction temperature testing system, characterized in that, The junction temperature testing system includes a first current unit, a second current unit, a computation unit, and a control unit; the method includes: The first current unit outputs a first current with a surge current waveform. At a first time point when the first current unit outputs the first current, the electrical connection between the first current unit and the device under test is turned on; at a second time point when the first current unit outputs the first current, the electrical connection between the first current unit and the device under test is turned off; wherein, the second time point is after the first time point; Confirm whether the time between the first time point and the second time point has reached the preset time; If the time between the first time point and the second time point does not reach the preset time, at the first time point when the first current unit outputs the first current, the electrical connection between the first current unit and the device under test is turned on; at the third time point when the first current unit outputs the first current, the electrical connection between the first current unit and the device under test is turned off. The second current unit is used to output a second current to the device under test; When the connection between the first current unit and the device under test is disconnected, the voltage of the device under test is acquired, and the junction temperature of the device under test is calculated based on the voltage of the device under test.

9. The junction temperature testing method as described in claim 8, characterized in that, Also includes: Confirm whether the time between the first time point and the third time point has reached a preset time; If the time between the first time point and the third time point does not reach the preset time, at the first time point when the first current unit outputs the first current, the electrical connection between the first current unit and the device under test is turned on; at the i-th time point when the first current unit outputs the first current, the electrical connection between the first current unit and the device under test is turned off. Where i equals 4, 5, 6, ... n; the time between the i-th time point and the (i-1)-th time point is equal to the time between the second time point and the third time point.

10. The junction temperature testing method as described in claim 8 or 9, characterized in that, Also includes: When the connection between the first current unit and the device under test is disconnected, the voltage of the device under test is sampled, and the junction temperature of the device under test is calculated based on the voltage of the device under test.

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