Device and method for calibrating transient thermal resistance of diode transient thermal resistance tester

Abstract

The invention discloses a device and method for calibrating the transient thermal resistance of a diode transient thermal resistance tester, and the device comprises a waveform recorder and a function / arbitrary waveform generator, and the anode of a tested diode is connected with the current positive end S1 of the diode transient thermal resistance tester and the positive end of the external triggering input end of the function / arbitrary waveform generator. The cathode of the tested diode is connected with the current negative end S2 of the diode transient thermal resistance tester and the negative end of the external trigger input end of the function / arbitrary waveform generator. The voltage sampling positive end S3 of the diode transient thermal resistance tester is connected with the voltage measuring positive end of the waveform recorder and the positive end of the output end of the function / arbitrary waveform generator; the voltage sampling negative end S4 of the diode transient thermal resistance tester is connected with the voltage measuring negative end of the waveform recorder and the negative end of the output end of the function / arbitrary waveform generator; the technical problems that the transient thermal resistance measuring range, the upper limit and the lower limit cannot be calibrated and the calibration precision is not high in the prior art are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of measuring instrument calibration, and in particular relates to a device and method for calibrating transient thermal resistance of a diode transient thermal resistance tester. Background Art

[0002] Transient thermal resistance is the main indicator of power semiconductors. It is directly related to the device's basic electrical and mechanical parameters such as rated current, peak voltage drop, dissipated power, maximum junction temperature, and tensile properties. It is a characterization of many quality indicators of the device.

[0003] The transient thermal resistance adopts the test method of large current pulse heating and small current testing, and automatically calculates the test results. It can maximize the heat transfer influencing factors during transient heating of the tested tube, reveal the welding quality of the tube core on the heat dissipation base or the quality of the tube core metallization layer, and thus provide an effective testing method for the quality assurance system of semiconductor power devices.

[0004] The transient heating current at a specific point can be accurately and repeatedly achieved. At the same time, the diode has the advantage of a good linear relationship between the forward voltage drop and the junction temperature under the condition of a constant small current, and the forward voltage variable before and after heating, namely ΔV F To express transient thermal resistance, it provides convenience for users to interpret and has been widely recognized in the industry and abroad.

[0005] Figure 1 This is the wiring diagram of the diode transient thermal resistance tester. The diode transient thermal resistance tester has 4 terminals, S1 and S2 are current terminals, S1 is the positive terminal, S2 is the negative terminal, the current flows out from S1 and flows into S2. S3 and S4 are voltage sampling terminals, S3 is the positive terminal, and S4 is the negative terminal. The 4-wire measurement method is adopted, that is, S1 and S3 are connected to the anode of the diode under test at the same point S5, S2 and S4 are connected to the cathode of the diode under test at the same point S6, and a forward variable current I is added to the diode D, and the forward voltage change ΔV at both ends is measured. F .

[0006] The transient thermal resistance tester is mainly composed of a power supply, a pulse current source, a pulse voltage measurement unit, a display unit, a control unit and a test fixture. The test schematic diagram is as follows Figure 2 As shown, I s is the current source, R s is the internal resistance of the current source. L is the load resistance, I is the current flowing through the diode D under test, D is the diode under test, V FM is the forward voltage and GND is the ground terminal.

[0007] The pulse current source output is as follows Figure 3 As shown in the forward current waveform, the horizontal axis t is time and the vertical axis I is current. In the T1 period, the pulse current source outputs a small forward test current I m , added to the diode D, the diode D generates a forward voltage `V FM1 ,like Figure 3 The forward voltage waveform shown in ② is shown in Figure 2. The horizontal axis t is time and the vertical axis V FM is the forward voltage. At time t1, the current output by the pulse current source changes from the forward test current I m Jump to forward heating current I t , maintaining the T2 period, the diode D outputs a forward voltage V FM2 At time t2, the current output by the pulse current source changes from the forward heating current I t Jump to the forward test current I m , maintain T3 time period,

[0008] Diode D output forward voltage V FM3 , then the transient thermal resistance ΔV F Defined as:

[0009] ΔV F =V FM1 -V FM3

[0010] Where:

[0011] ΔV F —Transient thermal resistance, unit: V;

[0012] V FM1 —In the T1 period, add a forward test current I m When , the forward voltage of the diode, unit: V;

[0013] V FM3 - In the T3 period, add the forward test current I m The forward voltage of the diode at , unit: V.

[0014] Figure 3 The figure ② shows the sampling moment and sampling time of the voltage sampling terminal of a typical diode transient thermal resistance tester, V FM1 It is sampled and measured in the T5 period before t1, V FM2 It is sampled and measured in the T6 period after t1, V FM3 It is sampled and measured after a delay of T7 time period from time t2. Different manufacturers may have different values. For example, the DVF-92A automotive diode transient thermal resistance test system produced by Huaqiang Electronic Technology Co., Ltd. in Jinhua Science and Technology Park, Zhejiang Province, has T5=0.5ms, T6=1ms, T7=50μs~10ms, etc.

[0015] Due to the negative temperature coefficient of the diode, the forward voltage decreases as the temperature increases, and vice versa, the forward voltage increases as the temperature decreases. In the T1 period, the forward test current I m The diode heating is negligible, the forward voltage changes very little, and the forward voltage in the T1 period is approximately a horizontal straight line. At t1, the current output by the pulse current source changes from the forward test current I m Jump to a larger heating current I t , the temperature of diode D gradually increases, and the forward voltage gradually decreases as the temperature gradually increases. Maintaining the T2 period, the forward voltage is a straight line sloping downward to the right. At time t2, the current output by the pulse current source changes from the heating current I t Jump to test current I m When the current decreases, the temperature of the diode D gradually decreases, and the forward voltage gradually increases as the temperature decreases. The forward voltage is a straight line that tilts upward to the right during the T3 period. Due to the heating during the T2 period, the temperature of the diode in the T1 period is lower than that in the T3 period, so: V FM1 ≥V FM3 .

[0016] At present, similar instruments and equipment for testing diode transient thermal resistance at home and abroad are all developed and produced according to this principle, and have been widely recognized at home and abroad. For example, the DVF-92A automotive diode transient thermal resistance test system produced by Huaqiang Electronic Technology Co., Ltd. in Jinhua Science and Technology Park, Zhejiang Province, the BR2984A high-power tube transient thermal resistance tester produced by Zhejiang Jinhua Huafeng Instrument Research Institute, the DVF3120 automotive diode transient thermal resistance tester produced by Jinhua Jinlong Automation Technology Co., Ltd., and the ES-DVF-710DW forward thermal resistance test bench produced by Zhengzhou Yixin Electronic Technology Co., Ltd. These types of instruments are widely used in the scientific research and production of diodes to test the transient thermal resistance of diodes.

[0017] At present, there is no dedicated calibration device or calibration specification for the calibration of diode transient thermal resistance tester. A typical current calibration method is to use an oscilloscope as a standard instrument and connect the positive and negative terminals of one voltage measurement channel of the oscilloscope to Figure 1 The S5 and S6 terminals are measured. Figure 3 As shown in ②, the forward voltage waveform is measured. FM1 、V FM3 Then use the formula ΔV F2 =V FM1 -V FM3 Calculate ΔV F2 , as the measured value, and the transient thermal resistance ΔV measured by the diode transient thermal resistance tester F1 , calculate the transient thermal resistance measurement error as follows:

[0018] ΔV=ΔV F1 -ΔV F2

[0019] Where:

[0020] ΔV—Transient thermal resistance measurement error, unit: V;

[0021] ΔV F1 —Transient thermal resistance measured by diode transient thermal resistance tester, unit: V;

[0022] ΔV F2 —Transient thermal resistance measured by an oscilloscope, unit: V.

[0023] If ΔV is within the maximum allowable error range, the diode transient thermal resistance tester is qualified, otherwise it is unqualified.

[0024] There are four difficulties with this calibration method:

[0025] First: Since the calibrated transient thermal resistance is determined by the transient thermal resistance of the diode, and the transient thermal resistance of each type of diode is within a fixed range, the transient thermal resistance points to be calibrated cannot be accurately set, such as 0.1V, 0.5V, 1V, 1.5V, 2V, 2.2V, etc., especially the upper and lower limits of the transient thermal resistance measurement, resulting in the calibrated points not covering the entire measuring range.

[0026] Second: Even for diodes from the same batch, the transient thermal resistance of each diode is different. The transient thermal resistance of some diodes is very small. For example, when used to generate transient thermal resistance during calibration, it exceeds the lower limit of the oscilloscope voltage measurement, and thus the transient thermal resistance of the diode cannot be calibrated.

[0027] Third: Even if it is the same diode, if the stability is poor, the transient thermal resistance will fluctuate randomly within a certain range, and the starting and ending points of the transient thermal resistance sampling time of the diode transient thermal resistance tester will be different from the starting and ending points of the oscilloscope sampling time. Figure 3 The forward voltage waveform shown in ② is V of the T1, T2, and T3 segments. FM1 、V FM2 、V FM3 It is not a straight line, but a randomly undulating wavy line, so it is difficult to accurately calculate the transient thermal resistance, resulting in large measurement errors. It is difficult to make a correct judgment whether the transient thermal resistance meets the technical index requirements.

[0028] Fourth: Use an oscilloscope as a standard to measure the forward voltage waveform across the diode. Due to the impedance shunting effect and the interference introduced at the input end of the oscilloscope, there are many interference signals on the measured waveform, so the calibration accuracy is not high.

[0029] At present, the main technical indicators of typical diode transient thermal resistance testers are:

[0030] Test current I m Range: 10mA~1000mA, maximum allowable error: ±5%; test current pulse width range: 10ms~1000ms, maximum allowable error: ±5%.

[0031] Heating current I t Range: 5A~150A, maximum allowable error: ±5%; heating current pulse width range: 10ms~10s, maximum allowable error: ±5%.

[0032] Forward voltage V FM Measuring range: 0.1V~2.2V, full-scale error: ±5%.

[0033] Transient thermal resistance ΔV F Measuring range: 0.0mV~255.0mV, full scale error: ±5%.

[0034] Ambient temperature: (20~30)℃, relative humidity: ≤80%. Summary of the invention

[0035] The technical problem to be solved by the present invention is to provide a device and method for calibrating the transient thermal resistance of a diode transient thermal resistance tester, so as to solve the technical problems that the prior art cannot calibrate the transient thermal resistance range and the upper and lower limits, and the calibration accuracy is not high.

[0036] Technical solution of the present invention:

[0037] A device for calibrating transient thermal resistance of a diode transient thermal resistance tester. The device comprises a waveform recorder and a function / arbitrary waveform generator. The anode of the diode to be tested is connected to a positive current terminal S1 of the diode transient thermal resistance tester and a positive end of an external trigger input terminal of the function / arbitrary waveform generator, and the cathode of the diode to be tested is connected to a negative current terminal S2 of the diode transient thermal resistance tester and a negative end of an external trigger input terminal of the function / arbitrary waveform generator; a positive voltage sampling terminal S3 of the diode transient thermal resistance tester is connected to a positive voltage measurement terminal of the waveform recorder and a positive end of an output terminal of the function / arbitrary waveform generator, and a negative voltage sampling terminal S4 of the diode transient thermal resistance tester is connected to a negative voltage measurement terminal of the waveform recorder and a negative end of an output terminal of the function / arbitrary waveform generator.

[0038] A calibration method for a transient thermal resistance calibration device of a diode transient thermal resistance tester, the method comprising:

[0039] Step 1: Turn on the power of the waveform recorder, function / arbitrary waveform generator and diode transient thermal resistance tester, preheat them and reach the specified preheating time;

[0040] Step 2: Set the functions and parameters of the diode transient thermal resistance tester;

[0041] Step 3: Set the functions and parameters of the function / arbitrary waveform generator;

[0042] Step 4: Set the functions and parameters of the waveform recorder;

[0043] Step 5, accurately calibrating the square wave voltage signal output by the function / arbitrary waveform generator;

[0044] Step 6. Start the transient thermal resistance measurement function of the diode transient thermal resistance tester and perform the test. After the test, read the transient thermal resistance indication and compare it with the difference between the high level and the low level of the square wave signal output by the function / arbitrary waveform generator, i.e., the amplitude, to determine whether the transient thermal resistance meets the technical index requirements.

[0045] The method for setting the functions and parameters of the diode transient thermal resistance tester includes: setting the test current I of the diode transient thermal resistance tester according to the parameters to be calibrated and the calibration point m , heating current I t , test current I m The T1 and T3 times, heating current I t time T2, voltage sampling times T5, T6 and T7.

[0046] The method for setting the functions and parameters of the function / arbitrary waveform generator includes: according to the parameters to be calibrated and the calibration points, setting the output waveform to a square wave, setting the period of the square wave, the high level and the low level of the square wave amplitude, making the difference between the high level and the low level equal to the transient thermal resistance to be calibrated, setting the square wave duty cycle, turning on the pulse train function, setting the output to 1 pulse, setting the trigger function to external trigger, rising edge trigger and trigger delay time to 0, and setting the output impedance to high impedance.

[0047] The method for setting the functions and parameters of the waveform recorder includes: selecting the measurement channel according to the parameters to be calibrated and the calibration points, setting it to the voltage measurement function, the input impedance to 1MΩ, the coupling to DC, and setting the horizontal scanning coefficient t / div and the vertical deflection coefficient V / div.

[0048] The method for accurately calibrating the square wave voltage signal output by the function / arbitrary waveform generator includes: accurately calibrating the square wave voltage signal output by the function / arbitrary waveform generator, adjusting the high level and low level of the output amplitude of the function / arbitrary waveform generator, so that the value measured by the waveform recorder reaches the required specified value.

[0049] Beneficial effects of the present invention:

[0050] The invention is simple, reliable and easy to use. A waveform recorder and a function / arbitrary waveform generator constitute a calibration device.

[0051] The transient thermal resistance of the diode is simulated by using the difference between the high level and low level of the square wave voltage signal with high precision and good stability output by the function / arbitrary waveform generator. At the same time, the high level and low level of the square wave voltage signal output by the function / arbitrary waveform generator can be accurately adjusted by a waveform recorder, and the maximum allowable error of the output square wave voltage amplitude can be increased to ±0.3%. The measurement standard is 3 times higher than the parameter requirements of the calibrated instrument, and the precise calibration of the transient thermal resistance of the diode transient thermal resistance tester is achieved.

[0052] The transient thermal resistance of the diode is simulated by using the difference between the high level and the low level of the high-precision square wave voltage signal output by the function / arbitrary waveform generator, and the difference between the high level and the low level can be set arbitrarily, that is, the transient thermal resistance of the simulated diode can be set arbitrarily. Therefore, any point within the transient thermal resistance measurement range of the diode transient thermal resistance tester can be calibrated, covering the entire range.

[0053] The invention solves the technical problems that the prior art cannot calibrate the transient thermal resistance range and the upper and lower limits and the calibration accuracy is not high. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 Wiring diagram for diode transient thermal resistance test;

[0055] Figure 2 This is the transient thermal resistance test schematic diagram;

[0056] Figure 3 is the forward current voltage waveform;

[0057] Figure 4 Wiring diagram for transient thermal resistance calibration;

[0058] Figure 5 2 are current and voltage waveforms of the embodiment. DETAILED DESCRIPTION

[0059] The calibration device of the present invention comprises a waveform recorder and a function / arbitrary waveform generator.

[0060] Figure 4This is a transient thermal resistance calibration wiring diagram of a diode transient thermal resistance tester. The diode transient thermal resistance tester has four terminals. S1 and S2 are current terminals, S1 is the positive terminal, S2 is the negative terminal, and the current flows out from S1 and flows into S2. S3 and S4 are voltage sampling terminals, S3 is the positive terminal, and S4 is the negative terminal. The anode of the diode under test is connected to the positive terminal of S1 and the external trigger input terminal of the function / arbitrary waveform generator, and the cathode of the diode under test is connected to the negative terminal of S2 and the external trigger input terminal of the function / arbitrary waveform generator. S3 is connected to the positive voltage measurement terminal of the waveform recorder and the positive terminal of the output terminal of the function / arbitrary waveform generator, and S4 is connected to the negative voltage measurement terminal of the waveform recorder and the negative terminal of the output terminal of the function / arbitrary waveform generator.

[0061] The principle of calibration is to use the amplitude of the square wave voltage signal output by the function / arbitrary waveform generator to simulate the transient thermal resistance of the diode, add it to the voltage sampling terminal of the diode transient thermal resistance tester and test it. The waveform recorder is used to accurately adjust the amplitude of the square wave voltage signal output by the function / arbitrary waveform generator, and the forward voltage generated by the current on the diode D is used to trigger the function / arbitrary waveform generator to output the required square wave voltage signal waveform.

[0062] The transient thermal resistance calibration method of the diode transient thermal resistance tester includes:

[0063] Step 1: Preheat the instruments: Turn on the power of the waveform recorder, the power of the function / arbitrary waveform generator, and the power of the diode transient thermal resistance tester. Preheat these three instruments and let them reach the specified preheating time. Figure 4 Connect the instrument;

[0064] Step 2: Set the functions and parameters of the diode transient thermal resistance tester: According to the parameters to be calibrated and the calibration points, set the test current I of the diode transient thermal resistance tester. m , heating current I t , test current I m The T1 and T3 times, heating current I t Time T2, voltage sampling time T5, T6, T7, etc.;

[0065] Step 3. Set the function and parameters of the function / arbitrary waveform generator: according to the parameters and calibration points to be calibrated, set the output waveform to a square wave, set the period of the square wave, the high level and low level of the square wave amplitude, so that the difference between the high level and the low level is equal to the transient thermal resistance to be calibrated. Set the square wave duty cycle. Turn on the pulse train function and set the output to 1 pulse. Set the trigger function to external trigger, rising edge trigger, and the trigger delay time to 0. Set the output impedance to high impedance;

[0066] Step 4. Set the functions and parameters of the waveform recorder: According to the parameters to be calibrated and the calibration points, select the measurement channel, set it to voltage measurement function, input impedance to 1MΩ, coupling to DC. Set the horizontal scanning coefficient t / div and vertical deflection coefficient V / div;

[0067] Step 5, accurately calibrate the square wave voltage signal output by the function / arbitrary waveform generator: adjust the high level and low level of the output amplitude of the function / arbitrary waveform generator so that the value measured by the waveform recorder reaches the required specified value;

[0068] Step 6. Start the transient thermal resistance measurement function of the diode transient thermal resistance tester and perform the test. After the test, read the transient thermal resistance indication and compare it with the difference between the high level and the low level of the square wave signal output by the function / arbitrary waveform generator, i.e., the amplitude, to determine whether its transient thermal resistance meets the technical index requirements.

[0069] Step 7. Remove all connecting cables and turn off the power of the waveform recorder, diode transient thermal resistance tester, and function / arbitrary waveform generator.

[0070] This embodiment takes the calibration of the transient thermal resistance of the BR2984A high-power tube transient thermal resistance tester produced by Zhejiang Jinhua Huafeng Instrument Research Institute as an example for explanation. Its main technical indicators are:

[0071] Test current I m Range: 20mA~1A, maximum allowable error: ±(5% reading + 2mA). Test current pulse width range: 30ms~1000ms, maximum allowable error: ±(2% reading + 0.1ms).

[0072] Heating current I t It is a rectangular wave, heating current range: 5A ~ 100A, maximum allowable error: ± (5% reading + 0.5A). Heating current pulse width range: 30ms ~ 1000ms (30ms, 100ms, 300ms, 1000ms four gears optional), maximum allowable error: ± (2% reading + 0.1ms).

[0073] Forward voltage V FM Measuring range: 0.5V~2.0V, maximum allowable error: ±5%.

[0074] Transient thermal resistance ΔV F Measuring range: 0.0mV~255.0mV, resolution: 1mV, maximum allowable error: ±(3% reading + 5 digits).

[0075] The function / arbitrary waveform generator used in this embodiment is the 33522A function / arbitrary waveform generator produced by Keysight, USA. Its main technical indicators are: internal crystal frequency: 10 MHz, relative frequency deviation: ±6×10 -8 ; Frequency range: 1μHz~30MHz (corresponding period range: 33.3ns~1×10 6 s). Voltage amplitude range: 2mV~20V, resolution: 0.1mV, maximum allowable error: ±1%. Output impedance: 50Ω or high impedance. Output waveforms include: DC, sine wave, square wave, pulse wave, triangle wave, ramp wave, arbitrary wave, etc. Rise and fall time of square wave ≤5ns.

[0076] The waveform recorder used in this embodiment is the 8861-50 waveform recorder produced by HIOKI of Japan. The main technical indicators are: internal crystal frequency: 10MHz, relative frequency deviation: ±1×10 -6 . Equipped with 8957 high-resolution unit, bandwidth: DC ~ 300kHz, maximum allowable error: ±3dB. Vertical deflection coefficient range: 50μV / div ~ 20V / div. Voltage measurement range: 50μV ~ 400V, maximum allowable error: ±0.3%. Input impedance: 1MΩ, coupling mode: DC, AC, with filter function. Horizontal scanning coefficient range: 0.5μs / div ~ 1h / div, display range: horizontal 25div, vertical 20div, resolution: 0.1div.

[0077] Taking the test of F40 automotive rectifier diode produced by Guizhou Yaguang Electronic Technology Co., Ltd. as an example, the BR2984A high-power tube transient thermal resistance tester is set up.

[0078] Set the test current I m =100mA, heating current I t =100A, T1=T2=T3=100ms, current waveform is as follows Figure 5 As shown in ③, the horizontal axis t is time and the vertical axis I is current.

[0079] Now we use the calibrated transient thermal resistance ΔV F Taking the 50.0mV point as an example, the manual setting method of the functions and parameters of the 33522A function / arbitrary waveform generator and the 8861-50 waveform recorder is explained.

[0080] The parameters of the square wave signal output by the 33522A function / arbitrary waveform generator are as follows: period is 400ms, duty cycle is 50%; high level amplitude is 550.0mV, low level amplitude is 500.0mV; delay time is 0ns; external trigger function, rising edge triggering; pulse train function, 1 pulse; output impedance is high impedance. Setting method:

[0081] 1. Select the square wave function

[0082] Press the Waveforms button on the front panel and press the corresponding square wave soft key on the display.

[0083] 2. Parameter settings

[0084] Press the Parameters button on the front panel, press the Units button on the front panel, and press the Frequency and Period soft keys on the display to select Period. Press the Amp / Offset and Amp / Offs High / Low soft keys on the display to select High / Low. Press the High Level soft key on the display to set the high level to 550.0mV, and press the Low Level soft key on the display to set the low level to 500.0mV.

[0085] 3. Output impedance setting

[0086] Press the channel 1 button on the front panel, press the corresponding output load (Output Load) soft key on the display screen, press the corresponding set to high impedance (Set To High Z) soft key on the display screen, set it to high impedance (High Z), and press the confirmation (Done) soft key. Press the output off on (Output Off On) soft key and select on (On), that is, the output of channel 1 is turned on.

[0087] 4. Pulse train function setting

[0088] Press the Burst button on the front panel, and then press the Burst button to turn the pulse on and off.

[0089] Press the N Cycle soft key, and then press the #Cycles soft key to set the number of cycles to 1Cyc.

[0090] 5. Trigger settings

[0091] Press the trigger button (Trigger) on the front panel, press the trigger source (Source) soft key corresponding to the display screen, press the external trigger (Ext) soft key corresponding to the display screen. Press the trigger slope (Slope) soft key corresponding to the display screen, press the rising edge (Rising) trigger soft key corresponding to the display screen, press the delay (Delay) soft key corresponding to the display screen, set the delay time to 0ns, that is, no delay, and press the confirmation (Done) soft key.

[0092] 8861-50 waveform recorder function and parameter manual setting method:

[0093] Select channel 1 of the 8957 high-resolution unit, set it to voltage measurement function, set the input impedance to 1MΩ, set the coupling to DC, set the horizontal scan coefficient to 50ms / div, and the vertical deflection coefficient to 50mV / div. Since the period of the square wave voltage signal output by the function / arbitrary waveform generator is 400ms, the corresponding frequency is 2.5Hz, the principle of selecting the filter bandwidth of channel 1 of the 8861-50 waveform recorder 8957 high-resolution unit is: the filter bandwidth is more than 10 times the frequency of the square wave signal output by the function / arbitrary waveform generator, so that the waveform measured by the waveform recorder will not be distorted. The filter bandwidth of the waveform recorder has 6 levels to choose from: 0ff, 5Hz, 50Hz, 500Hz, 5kHz, and 50kHz. 0ff means turning off the filter. Here, 50Hz is selected. In this way, interference signals above 50Hz can be filtered out, thereby achieving accurate measurement.

[0094] Since the amplitude of the square wave voltage signal output by the function / arbitrary waveform generator is stable, the amplitude of the square wave voltage signal output by the function / arbitrary waveform generator can be accurately adjusted within ±0.3% using the 8861-50 waveform recorder. For example, in this example, the high level of the square wave voltage signal output by the function / arbitrary waveform generator is set to 550.0mV and the low level is set to 500.0mV. If the high level measured by the waveform recorder is not 550.0mV and the low level is not 500.0mV, the high level and low level of the square wave voltage signal output by the function / arbitrary waveform generator are adjusted respectively until the high level V measured by the waveform recorder is H 550.0mV, low level V L Until it is 500.0mV (Note: The maximum allowable error of the square wave voltage signal output by the function / arbitrary waveform generator is: ±1%, and the maximum allowable error of the transient thermal resistance of the BR2984A high-power tube transient thermal resistance tester is: ±(3% reading + 5 characters), which meets the measurement standard that is 3 times higher than the technical indicators of the calibrated instrument. The high and low level amplitudes of the square wave voltage signal output by the function / arbitrary waveform generator do not need to be accurately adjusted by a waveform recorder, and can be directly used as a standard signal).

[0095] Transient thermal resistance calibration wiring diagram is as follows Figure 4 shown.

[0096] Press the test key of the BR2984A high-power tube transient thermal resistance tester, and the current terminals S1 and S2 will output Figure 5 The current waveform of ③ is shown in Figure 3. At time t0, the output test current I m The current is 100mA. This current generates a forward voltage of about 0.6V on the diode D under test, which is added to the external trigger input of the function / arbitrary waveform generator, thereby triggering the function / arbitrary waveform generator, and its output terminal outputs Figure 5 The voltage waveform shown in ④, high level V H 550.0mV, low level V L The voltage is 500.0mV and is added to the voltage sampling terminals S3 and S4 of the BR2984A high-power tube transient thermal resistance tester. Figure 5 In the voltage waveform shown in ④,

[0097] T1=T2=T3=T4=100ms.

[0098] The time period from t0 to t1, i.e. T1, is 100ms. During this period, the voltage sampling terminal of the transient thermal resistance tester is Figure 5 The voltage of the voltage waveform shown in ④ during the T1 period is measured, and the measured value is V FM1 The time period from t1 to t2, i.e. T2, is 100ms, and the output heating current I t At the same time, during this process, the voltage sampling terminal of the transient thermal resistance tester is Figure 5 The voltage of the voltage waveform shown in ④ during the T2 period is measured, and the measured value is V FM2 The time period from t2 to t3, i.e. T3, is 100ms, and the output test current I m At the same time, during this process, the voltage sampling terminal of the transient thermal resistance tester is Figure 5 The voltage of the voltage waveform shown in ④ during the T3 period is measured, and the measured value is V FM3 .because Figure 5 The voltage waveform of ④ is high level V H and low level V L are two horizontal lines, so the voltage sampling results of the transient thermal resistance tester at any time in the T1 and T3 time periods are the same. Then the transient thermal resistance ΔV measured by the transient thermal resistance tester is F1 =ΔV F1 =

[0099] V FM1 -V FM3 , the transient thermal resistance tester automatically calculates ΔV F1, and displayed. The transient thermal resistance measurement error ΔV is calculated as follows:

[0100] ΔV=ΔV FM1 -(V H -V L )

[0101] Known: V H -V L =50.0mV, the transient thermal resistance tester measured value is: ΔV F1 =50.3mV, then:

[0102] Absolute error: ΔV = ΔV FM1 -(V H -V L )=50.3mV-50.0mV=0.30mV.

[0103] Relative error: ΔV / (V H -V L )=0.30mV / 50.0mV=0.60%.

[0104] Main technical indicators:

[0105] The calibration device consists of a waveform recorder and a function / arbitrary waveform generator. The main technical indicators are: internal crystal frequency: 10MHz, relative frequency deviation: ±6×10 -8 ; Frequency range: 1μHz~30MHz (corresponding period range: 33.3ns~1×10 6 s). Voltage amplitude (peak-to-peak) range: 2mV~20V, resolution: 0.1mV, maximum allowable error: 0.3%. Output impedance: 50Ω or high impedance. Output waveforms include: square wave, sine wave, pulse wave, triangle wave, ramp wave, arbitrary wave, DC, etc.

Claims

1. A device for calibrating transient thermal resistance of a diode transient thermal resistance tester, the device comprising a waveform recorder and a function / arbitrary waveform generator, characterized in that: The anode of the diode under test is connected to the positive current terminal S1 of the diode transient thermal resistance tester and the positive terminal of the external trigger input terminal of the function / arbitrary waveform generator, and the cathode of the diode under test is connected to the negative current terminal S2 of the diode transient thermal resistance tester and the negative terminal of the external trigger input terminal of the function / arbitrary waveform generator; the positive voltage sampling terminal S3 of the diode transient thermal resistance tester is connected to the positive voltage measurement terminal of the waveform recorder and the positive terminal of the output terminal of the function / arbitrary waveform generator, and the negative voltage sampling terminal S4 of the diode transient thermal resistance tester is connected to the negative voltage measurement terminal of the waveform recorder and the negative terminal of the output terminal of the function / arbitrary waveform generator.

2. The calibration method of a diode transient thermal resistance tester transient thermal resistance calibration device as claimed in claim 1, characterized in that: The method comprises: Step 1: Turn on the power of the waveform recorder, function / arbitrary waveform generator and diode transient thermal resistance tester, preheat them and reach the specified preheating time; Step 2: Set the functions and parameters of the diode transient thermal resistance tester; Step 3: Set the functions and parameters of the function / arbitrary waveform generator; Step 4: Set the functions and parameters of the waveform recorder; Step 5, accurately calibrating the square wave voltage signal output by the function / arbitrary waveform generator; Step 6. Start the transient thermal resistance measurement function of the diode transient thermal resistance tester and perform the test. After the test, read the transient thermal resistance indication and compare it with the difference between the high level and the low level of the square wave signal output by the function / arbitrary waveform generator, i.e., the amplitude, to determine whether the transient thermal resistance meets the technical index requirements.

3. The calibration method of a diode transient thermal resistance tester transient thermal resistance calibration device according to claim 2, characterized in that: The method for setting the functions and parameters of the diode transient thermal resistance tester includes: setting the test current I of the diode transient thermal resistance tester according to the parameters to be calibrated and the calibration point m , heating current I t , test current I m The T1 and T3 times, heating current I t time T2, voltage sampling times T5, T6 and T7.

4. The calibration method of a diode transient thermal resistance tester transient thermal resistance calibration device according to claim 2, characterized in that: The method for setting the functions and parameters of the function / arbitrary waveform generator includes: according to the parameters to be calibrated and the calibration points, setting the output waveform to a square wave, setting the period of the square wave, the high level and the low level of the square wave amplitude, making the difference between the high level and the low level equal to the transient thermal resistance to be calibrated, setting the square wave duty cycle, turning on the pulse train function, setting the output to 1 pulse, setting the trigger function to external trigger, rising edge trigger and trigger delay time to 0, and setting the output impedance to high impedance.

5. The calibration method of a diode transient thermal resistance tester transient thermal resistance calibration device according to claim 2, characterized in that: The method for setting the functions and parameters of the waveform recorder includes: selecting the measurement channel according to the parameters to be calibrated and the calibration points, setting it to the voltage measurement function, the input impedance to 1MΩ, the coupling to DC, and setting the horizontal scanning coefficient t / div and the vertical deflection coefficient V / div.

6. The calibration method of a diode transient thermal resistance tester transient thermal resistance calibration device according to claim 2, characterized in that: The method for accurately calibrating the square wave voltage signal output by the function / arbitrary waveform generator includes: accurately calibrating the square wave voltage signal output by the function / arbitrary waveform generator, adjusting the high level and low level of the output amplitude of the function / arbitrary waveform generator, so that the value measured by the waveform recorder reaches the required specified value.

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