Thermal resistance test power adding device and method

Abstract

The present invention provides a thermal resistance test power addition device and method, the device comprising: a Kelvin subcircuit connected to each port of the device under test; a driving module, providing a driving voltage or a driving current to the device under test through the Kelvin subcircuit of the first port; a power supply, providing a power voltage to the device under test through the Kelvin subcircuit of the second port and the third port; a power current source, providing a power current to the device under test through the driving current line in the Kelvin subcircuit of the third port; a thermal resistance measurement module, connected in parallel to the second port and the third port or in parallel to the first port and the third port, for testing the voltage value before and after the device under test is powered on; a power current measurement module, used to measure the current value output by the power current source; a timing module, starting the timing when the measured current value reaches a preset threshold current. The present invention can ensure that the thermal power applied to the device is equal to the calculated value, reduce errors, and improve the accuracy of thermal resistance testing.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuit testing, and in particular to a thermal resistance testing and power adding device and method. Background Art

[0002] Thermal resistance is a key parameter in the thermal design of power devices and is a must-test parameter for mass production of power semiconductors. The mass production test method of power semiconductors usually adopts the dynamic thermal resistance test method, which mainly uses the temperature-sensitive electrical junction inside the device under test whose junction voltage changes with the temperature of the device under test. The main steps include establishing the small current required for thermal resistance parameter measurement, measuring the voltage value of the device under test, establishing the voltage and current required for power addition, starting the timing, stopping the timing after a period of time, and then establishing the small current required for thermal resistance parameter measurement again and measuring the voltage value of the device under test after power is added for a period of time, and then calculating the thermal resistance parameters of the device under test based on the two voltage values ​​measured before and after power addition.

[0003] During the thermal resistance test, the heat generated by the device under test = the voltage across the device under test × the current flowing through the device under test × the time of power addition. In current thermal resistance test equipment, the start time of calculating the power addition time is synchronized with the current start time, and the power current requires a certain amount of time to establish. Therefore, the actual thermal power added to the device under test will be less than the calculated value, resulting in thermal resistance calculation errors. Summary of the invention

[0004] In view of this, the main purpose of the present invention is to provide a thermal resistance test power addition device and method, by adding a power current measurement comparison function, determining the starting point of the power addition timing according to the measured waveform, ensuring that the thermal power applied to the device is equal to the calculated value, reducing errors and improving the accuracy of thermal resistance testing.

[0005] The technical solution adopted by the present invention is a thermal resistance test power adding device, comprising:

[0006] A Kelvin subcircuit connected to each port of the device under test, the Kelvin subcircuit comprising a driving current line and a sensing voltage line;

[0007] A driving module, providing a driving voltage or a driving current to the device under test through a Kelvin subcircuit at a first port of the device under test;

[0008] A power supply, providing a power voltage to the device under test through a Kelvin subcircuit at a second port and a third port of the device under test;

[0009] A power current source provides a power current to the device under test through a driving current line in a Kelvin subcircuit of a third port of the device under test;

[0010] A thermal resistance measurement module is connected in parallel between the second port and the third port of the device under test, and is used to test the thermal resistance parameters of the device under test before and after power is applied;

[0011] A power current measurement module, used to measure the current value output by the power current source;

[0012] The timing module starts timing when the measured current value reaches a preset threshold current.

[0013] As described above, the device first provides a power voltage to the device under test through a power power supply, and then provides a power current to the device under test through a power current source. Since the power current flowing through the device under test needs a certain time to reach the specified rated power current, in order to avoid the situation in which the power timing and the power current source are started synchronously in the traditional measurement method, resulting in the actual thermal power added to the device under test being less than the theoretical calculated value, the power current is measured by a power current measurement module, and a threshold current for starting the timing is calculated based on the actual measured change curve. When the power current output by the power current source reaches the threshold current, the timing is started, thereby ensuring that the thermal power added to the device under test is basically equivalent to the theoretical calculated value, thereby ensuring the accuracy of the thermal resistance test.

[0014] Further improvements include:

[0015] The current comparison module collects the current value measured by the power current measurement module, and when the current reaches a preset threshold value, outputs a start signal to the timing module.

[0016] As described above, by pre-storing the calculated threshold current in the current comparison module, when the power current output by the power current source gradually increases and reaches the threshold current, the current comparison module is triggered to output a start signal to the timing module, and then the timing is started.

[0017] Further improvements include:

[0018] The floating voltage source is connected in parallel to the two ends of the power current source to provide an operating voltage therefor.

[0019] From the above, the floating voltage source is used to provide an operating voltage for the power current source.

[0020] Wherein, when the device under test is a triode, the first port is the base, the second port is the collector, and the third port is the emitter;

[0021] When the device under test is a field effect transistor, the first port is a gate, the second port is a source, and the third port is a drain.

[0022] From the above, the device can be used for power addition and thermal resistance testing of field effect tubes or triodes. The principles are the same and only the corresponding ports need to be connected when in use.

[0023] Based on the above thermal resistance test power adding device, the present invention also provides a thermal resistance test power adding method, comprising the steps of:

[0024] Start the power supply and the power current source in sequence to provide the device under test with power voltage and power current;

[0025] Monitor the change of power current, and start timing when the power current reaches a preset threshold current;

[0026] When the timing ends, turn off the power supply and the power current source.

[0027] From the above, the method starts the power supply and the power current source in turn to provide the power voltage and the power current for the device under test, and uses the power current measurement module to monitor the power current output by the power current source in real time. When the power current reaches the preset threshold current, the timing module is started to perform thermal power timing, and the timing is continued until the end of the timing, and the power supply and the power current source are turned off. The method can start the timing by selecting the middle moment of the power current change curve, thereby reducing the situation where the actual thermal power added to the device under test is less than the theoretical calculated value caused by the power current establishment time, thereby ensuring the accuracy of the thermal resistance test.

[0028] Further improvement also includes the following steps:

[0029] Before and after power is applied to the device under test, the junction voltage values ​​of the device under test are measured respectively, and the thermal resistance parameters of the device under test are calculated based on the junction voltage values ​​before and after power is applied.

[0030] From the above, by measuring the junction voltage value before and after the power is applied to the device under test, the thermal resistance change of the device under test can be calculated.

[0031] Wherein, the threshold current is calculated according to the change curve of power current,

[0032]

[0033] Among them, I th is the threshold current, t0 is the start-up time of the power current source, and t1 is the time when the current provided by the power current source reaches the rated power current.

[0034] From the above, since the power current output by the power current source needs a certain time to reach the rated power current, that is, the change of the power current is presented as a curve that gradually rises with time. At this time, a threshold current is calculated based on the calculation function of the time from the start of the power current source to the time when the output current reaches the rated power current and the curve change. When the power current reaches the threshold current, the timing is started again, so that the actual power current applied to the device under test is equal to the theoretical calculated value. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the principle of the thermal resistance test power adding device of the present invention;

[0036] Figure 2 A flow chart of a method for adding power to thermal resistance test of the present invention;

[0037] Figure 3 It is the variation curve of power current of the present invention. DETAILED DESCRIPTION

[0038] Refer to the following Figure 1-Figure 3 The specific implementation of the thermal resistance testing power adding device and method of the present invention is described in detail.

[0039] like Figure 1 As shown, the thermal resistance test power adding device provided by the present invention takes the device under test as a MOS tube as an example, and the device includes Kelvin sub-circuits respectively connected to three ports of the device under test, and each Kelvin sub-circuit includes a sensing voltage line and a driving current line;

[0040] The driving module is connected in series to the gate of the device under test, and provides a driving voltage to the device under test through the Kelvin sub-circuits 2F and 2S of the gate, driving the device under test to turn on or off;

[0041] A power supply is connected in parallel to the source and drain of the device under test, and provides a power voltage to the device under test through the Kelvin sub-circuit 1F, 1S of the source and the Kelvin sub-circuit 3F, 3S of the drain of the device under test;

[0042] A power current source is connected in series to the drain of the device under test and provides a driving current to the device under test through a driving current line 3F in a Kelvin subcircuit of the drain;

[0043] A floating voltage source is connected in parallel to both ends of the power current source to provide a working voltage therefor;

[0044] The thermal resistance measurement module is connected in parallel to the source and drain of the device under test and is used to measure the voltage value of the device under test before and after power is applied;

[0045] A power current measurement module, connected to the power current source, and used for measuring the power current outputted from the power current source to the device under test in real time;

[0046] A current comparison module has a threshold current preset inside, and compares the power current measured by the power current measurement module with the threshold current. When the power current reaches the threshold current, a start timing signal is triggered to output;

[0047] The timer receives the start timing signal output by the current comparison module and counts the power timing.

[0048] Similarly, when the device under test is a triode, the gate, source and drain mentioned above can be replaced by the base, collector and emitter respectively. The principle remains unchanged and will not be elaborated here.

[0049] like Figure 2 As shown, based on the above-mentioned thermal resistance test power adding device, the thermal resistance test power adding method provided by the present invention includes the following steps:

[0050] S100: measuring the junction voltage value of the device under test before power is applied by using a thermal resistance measurement module;

[0051] S200: starting the power supply and the power current source in sequence to provide power voltage and power current to the device under test;

[0052] During the power application phase of the device under test, the power voltage across the device under test is usually established first, and then the power current of the device under test is established. The thermal power applied to the device under test can be calculated based on the power voltage and power current.

[0053] S300: monitoring the change of power current, and starting timing when the power current reaches a preset threshold current;

[0054] like Figure 3 As shown, the power current provided by the power current source to the device under test needs a certain time to reach the rated power current required for the thermal power. During the certain time, the change of the power current is presented as a curve that gradually increases with time. If the timing is synchronized at the moment when the power current source is started, the power current actually added to the device under test will be less than the theoretical value. Therefore, it is necessary to select a suitable threshold current according to the curve, and start the timing when the power current reaches the threshold current to ensure that the power current continuously added to the device under test during the timing period is equal to (infinitely close to) the theoretical value. The calculation formula of the threshold current is:

[0055]

[0056] Right now,

[0057]

[0058] Among them, I th is the threshold current, t0 is the start-up time of the power current source, and t1 is the time when the power current provided by the power current source reaches the rated power current.

[0059] S400: When the timing ends, the power supply and the power current source are turned off;

[0060] S500: measuring the junction voltage value of the device under test after power is applied through the thermal resistance measurement module;

[0061] By measuring the junction voltage values ​​before and after power is applied to the device under test and performing a differential operation, the change in the thermal resistance parameter of the device under test can be calculated.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A thermal resistance test power device, characterized in that: include: A Kelvin subcircuit connected to each port of the device under test, the Kelvin subcircuit comprising a driving current line and a sensing voltage line; A driving module, providing a driving voltage or a driving current to the device under test through a Kelvin subcircuit at a first port of the device under test; A power supply, providing a power voltage to the device under test through a Kelvin subcircuit at a second port and a third port of the device under test; A power current source provides a power current to the device under test through a driving current line in a Kelvin subcircuit of a third port of the device under test; A thermal resistance measurement module is connected in parallel to the second port and the third port or the first port and the third port of the device under test, and is used to test the voltage value of the device under test before and after power is applied; A power current measurement module, used to measure the current value output by the power current source; A timing module starts timing when the measured current value reaches a preset threshold current; The threshold current is calculated based on the change curve of the power current. Among them, I th is the threshold current, t0 is the start-up time of the power current source, and t1 is the time when the current provided by the power current source reaches the rated power current.

2. The device according to claim 1, characterized in that Also includes: The current comparison module collects the current value measured by the power current measurement module, and when the current reaches a preset threshold value, outputs a start signal to the timing module.

3. The device according to claim 1, characterized in that Also includes: The floating voltage source is connected in parallel to the two ends of the power current source to provide an operating voltage therefor.

4. The device according to claim 1, characterized in that When the device under test is a triode, the first port is the base, the second port is the collector or emitter, and the third port is the emitter or collector; When the device under test is a field effect transistor, the first port is a gate, the second port is a source or a drain, and the third port is a drain or a source; When the device under test is an insulated gate bipolar transistor, the first port is the gate, the second port is the emitter, and the third port is the collector; When the device under test is a diode, the second port is the positive pole and the third port is the negative pole.

5. A thermal resistance test and power addition method based on the device described in any one of claims 1 to 4, characterized in that: Includes steps: Start the power supply and the power current source in sequence to provide the device under test with power voltage and power current; Monitor the change of power current, and start timing when the power current reaches a preset threshold current; The threshold current is calculated based on the change curve of the power current. Among them, I th is the threshold current, t0 is the start-up time of the power current source, and t1 is the time when the current provided by the power current source reaches the rated power current; After the timing is over, turn off the power supply and the power current source.

6. The method according to claim 5, characterized in that Also includes the steps: Before and after power is applied to the device under test, the junction voltage values ​​of the device under test are measured respectively, and the thermal resistance parameters of the device under test are calculated based on the junction voltage values ​​before and after power is applied.

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