Method for verifying junction temperature reached by high-temperature reverse bias of Schottky diode

Abstract

The invention relates to the technical field of electron Schottky diode testing methods, in particular to a method for verifying that a Schottky diode reaches junction temperature through high-temperature reverse bias. Transient leakage current testing and series resistor voltage division are carried out on the detected Schottky diode in a nominal junction temperature environment to prevent thermal collapse, and whether the nominal junction temperature is reached or not is finally judged by dynamically adjusting the environment temperature and the reverse voltage and monitoring the change of the leakage current and the voltage at the two ends of the Schottky diode in real time. The method can accurately verify the junction temperature state of the Schottky diode in the high-temperature reverse bias test, effectively avoids thermal runaway failure, is suitable for batch detection, and has the characteristics of simple operation and high reliability.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic Schottky diode testing methods, and particularly to a method for verifying that the high-temperature reverse bias of a Schottky diode reaches the junction temperature. Background Art

[0002] When a Schottky diode undergoes a high-temperature reverse bias test, due to the large change in its leakage current in a high-temperature environment, it often exceeds the junction temperature, resulting in thermal breakdown failure of the product, or the test temperature is too low to reach the junction temperature, and it is impossible to accurately verify whether the product meets the junction temperature. Therefore, how to accurately verify that the high-temperature reverse bias of a Schottky diode reaches the junction temperature in actual production is a technical problem to be solved. Summary of the Invention

[0003] The problem to be solved by the present invention is to provide a method for accurately verifying that the high-temperature reverse bias of a Schottky diode reaches the junction temperature.

[0004] In view of the deficiencies of the prior art, the technical solution adopted by the present invention to solve its technical problems is: a method for verifying that the high-temperature reverse bias of a Schottky diode reaches the junction temperature, including the following steps:

[0005] Step 1. Transient leakage current reference test: Place multiple Schottky diode samples to be measured in a constant temperature environment with a nominal junction temperature T j , apply a reverse voltage V R , measure and record the leakage current values I R1 of each sample, and take the average current value as the reference value for determining the junction temperature;

[0006] Step 2. Build a series voltage-dividing protection circuit: At room temperature, connect a resistor R in series at the front end of the diode to be measured. The resistance value of the resistor R is selected according to the average current value :

[0007] When , R = 5 kΩ ± 5%;

[0008] When , R = 10 kΩ ± 5%;

[0009] Step 3. Dynamic temperature and voltage coordinated regulation, adjust the voltage V A across the Schottky diode according to the ambient temperature T DUT ;

[0010] Step 4. Junction temperature determination: Record the ambient temperature T A at this time. If it satisfies T j = T A + P × R ja ,

[0011] VDUT is the voltage across the Schottky diode, and R ja is the thermal resistance, then it is determined that the diode under test reaches the nominal junction temperature.

[0012] Preferably, step three specifically includes the following process:

[0013] 3.1. Apply a reverse voltage V R to the diode under test, and increase the ambient temperature T A at a rate of 1 - 3 °C / min, and monitor the leakage current I R in real time;

[0014] 3.2. When the ambient temperature T A reaches 0.6T j to 0.7T j , reduce the heating rate of the ambient temperature T A to 0.5 - 1 °C / min;

[0015] 3.3. If the increase in the monitored leakage current I R causes the voltage V DUT across the Schottky diode to be lower than the reverse voltage V R , then pause the heating of T A and manually or automatically adjust the voltage V DUT across the Schottky diode to make

[0016] the voltage V DUT across the Schottky diode return to the reverse voltage V R ±2%;

[0017] 3.4. Repeat step 3.3 until the monitored leakage current I R stabilizes within the average current value range and lasts for ≥ 30 minutes;

[0018] Preferably, the range of the reverse voltage V R is 70% - 100% of the rated reverse voltage of the Schottky diode and needs to be lower than 80% of the breakdown voltage of the Schottky diode.

[0019] Preferably, the thermal resistance R ja is measured by the steady-state power consumption method or the transient thermal impedance method, and the error range ≤ 10%.

[0020] Preferably, the constant temperature environment of the nominal junction temperature T j is provided by a high-precision oven, and the internal temperature uniformity of the oven ≤ ±1 °C, and the temperature control accuracy ≤ ±0.5 °C.

[0021] Preferably, the measurement of the monitored leakage current I R uses a high-precision microammeter, and the resolution ≤ 1 μA.

[0022] The sampling frequency ≥ 1 Hz.

[0023] Preferably, the method is applicable to Schottky diodes with a junction temperature range of 125°C to 200°C.

[0024] The beneficial effects of the present invention are as follows:

[0025] 1. Precise junction temperature determination and thermal breakdown protection

[0026] Reference leakage current method: By pre-measuring the reference value of the leakage current I j under the nominal junction temperature T R1 , combined with the dynamic temperature and pressure control strategy, comparing the monitored leakage current I R value with the average current value in the actual test, the error of junction temperature determination is controlled within ±5%, significantly improving the verification accuracy;

[0027] Voltage division protection mechanism: The series resistance R dynamically adjusts its resistance value (5 kΩ or 10 kΩ) according to the average current value , quickly divides the voltage when the leakage current suddenly changes, limits the voltage fluctuation across the Schottky diode within ±2%, effectively avoids the risk of thermal runaway, and reduces the incidence of thermal breakdown in the test by more than 90%;

[0028] 2. Stability of dynamic temperature and pressure coordinated control

[0029] Gradual heating strategy: When the ambient temperature T A rises to 60% - 70% of the nominal junction temperature, the heating rate is reduced from 1 - 3°C / min to 0.5 - 1°C / min. By reducing the influence of thermal inertia, it ensures that the device gradually approaches the target junction temperature under steady state;

[0030] Closed-loop voltage regulation: When the voltage V DUT across the Schottky diode deviates from the reverse voltage V R due to the increase in the leakage current I R , the voltage V DUT across the Schottky diode is manually or automatically adjusted (step size ≤ 5 V) to maintain the deviation between V [[ID=A]] DUT [[ID=B]]and V R ≤ 2%, ensuring the stable convergence of the test process;

[0032] 3. Wide applicability and batch detection efficiency

[0033] Universal design: By adapting the series resistance R for different leakage current levels (I R1 < 5 mA or ≥ 5 mA), and the thermal resistance R ja It should be noted that there seems to be an error in the original text where the variable name "V" has two different variable numberings in the same context (e.g., DUT and DUT ). I have translated it as accurately as possible based on the provided text. Also, the variable "I" has similar issues with different numberings in different parts of the text. This translation is based on the best understanding of the overall context.Flexible measurement (steady-state power consumption method / transient thermal impedance method). This method can cover all Schottky diodes with a junction temperature range of 125°C to 200°C.

[0034] Batch detection compatibility: Combining a high-precision oven (temperature uniformity ≤ ±1°C) with an automated monitoring device (microammeter resolution ≤ 1 μA), multiple groups of samples can be verified synchronously in a single test, and the detection efficiency is increased by 40% to 60%.

[0035] 4. Reliability verified by measured data

[0036] Experimental comparison results: Taking the model MBR10100H-5DL8 as an example, the leakage current fluctuation of the traditional method reaches ±20% at an ambient temperature of 120°C, while in the present invention, through the coordination of voltage division and temperature control, the leakage current is stabilized at 4.5 mA ± 5%, and the junction temperature determination error ≤ 3°C.

[0037] 5. Low cost and easy implementation

[0038] Simplified equipment requirements: It can be implemented only with a conventional high-precision oven, a microammeter, and an adjustable power supply, without the need for complex thermal imaging or transient test equipment, reducing the hardware input cost by more than 50%. Standardized operation process: Through a clear parameter selection table (such as resistance value, heating rate) and determination threshold (such as ), the human operation error is reduced, which is suitable for front-line production personnel to quickly master. Description of the drawings

[0039] Figure 1 is a schematic diagram of the circuit principle involved in the present invention;

[0040] Figure 2 is the flow chart in the method of the present invention. Detailed implementation manners

[0041] The present invention will be further described in detail below in conjunction with the drawings and specific implementation manners. The embodiments of the present invention are given for the purpose of illustration and description, and are not exhaustive or limited to the disclosed form. Many modifications and variations are obvious to those of ordinary skill in the art. The embodiments are selected and described to better illustrate the principles and practical applications of the present invention, and enable those of ordinary skill in the art to understand the present invention and thus design various embodiments with various modifications suitable for specific purposes.

[0042] To solve the problems in the background technology, the present invention proposes a method for verifying that a Schottky diode reaches the junction temperature under high-temperature reverse bias. The method of the present invention can accurately verify whether a Schottky diode reaches the nominal junction temperature, and the method of the present invention is applicable to Schottky diodes with a junction temperature range of 125°C to 200°C. It includes the following steps:

[0043] Step 1. Transient leakage current reference test: Place multiple Schottky diode samples to be measured in a constant temperature environment with a nominal junction temperature T j , apply a reverse voltage V R , measure and record the leakage current values I R1 of each sample, and take the average current value as the reference value for determining the junction temperature; the range of the reverse voltage V R is 70% - 100% of the rated reverse voltage of the Schottky diode and needs to be lower than 80% of the breakdown voltage of the Schottky diode.

[0044] Step 2. Build a series voltage - dividing protection circuit: At room temperature, connect a resistor R in series at the front end of the diode to be measured. The resistance value of the resistor R is selected according to the average current value :

[0045] When , R = 5kΩ ± 5%;

[0046] When , R = 10kΩ ± 5%;

[0047] Step 3. Dynamic temperature - voltage coordinated regulation, adjust the voltage V A across the Schottky diode according to the ambient temperature T DUT ;

[0048] Step 3 specifically includes the following process,

[0049] 3.1. Apply a reverse voltage V R to the diode to be measured, increase the ambient temperature T A at a rate of 1 - 3°C / min, and monitor the leakage current I R in real - time;

[0050] 3.2. When the ambient temperature T A reaches 0.6T j - 0.7T j , reduce the heating rate of the ambient temperature T A to 0.5 - 1°C / min;

[0051] 3.3. If the increase in the monitored leakage current I R causes the voltage V DUT across the Schottky diode to be lower than the reverse voltage V R , then pause the heating of T A and manually or automatically adjust the voltage V DUT across the Schottky diode to make the voltage V DUT across the Schottky diode return to the reverse voltage V R ± 2%;

[0052] ˉ

[0053] 3.4. Repeat step 3.3 until the monitored leakage current I R stabilizes within the range of the average current value I R1 ±5% and the duration is ≥ 30 minutes;

[0054] Step Four, Junction Temperature Judgment: Record the ambient temperature T at this time A , if it satisfies T j = T A + P × R ja , R ja is the thermal resistance, then it is determined that the measured diode reaches the nominal junction temperature. The thermal resistance R ja is measured by the steady-state power consumption method or the transient thermal impedance method, and the error range is ≤ 10%.

[0055] The constant temperature environment of the nominal junction temperature T j is provided by a high-precision oven. The internal temperature uniformity of the oven is ≤ ±1°C, and the temperature control accuracy is ≤ ±0.5°C.

[0056] Place the measured Schottky diode in a constant temperature environment with a nominal junction temperature of T j for testing. At this moment, the I R1 measured in this environment, and the leakage value in this environment at this time represents the leakage value when the Schottky diode reaches the junction temperature. A resistor R (generally recommended to be 10KΩ, and the resistance value can be adjusted according to the actual situation) is connected in series at the front end of the measured Schottky diode. This resistor plays a voltage-dividing role in the circuit. Due to the increase in temperature, the monitored leakage current I R of the Schottky diode changes more severely. The resistor R can instantaneously shunt the voltage across the Schottky diode, reduce power consumption, and prevent the thermal breakdown of the Schottky diode. Apply a reverse voltage V R across the Schottky diode at room temperature, and at the same time monitor the monitored leakage current I R across the Schottky diode. Gradually increase the ambient temperature T A . At this time, the Schottky diode is operating in a steady state. Therefore, when the ambient temperature approaches 2 / 3 of the nominal junction temperature T j , the heating rate needs to be slowed down to ensure that the Schottky diode remains stable in this environment before proceeding with subsequent operations.

[0057] During the entire test process, due to the series connection of the resistor R, the voltage V DUT (the value detected by the voltmeter) across the Schottky diode will decrease as the monitored leakage current I R increases. Therefore, it is necessary to monitor the voltage V DUT across the Schottky diode with a voltmeter. When the voltage V DUT across the Schottky diode is lower than the reverse voltage V R , it is necessary to pause increasing the ambient temperature T A, adjust the voltage V across the Schottky diode DUT , ensure that the voltage V across the Schottky diode DUT is always equal to the reverse voltage V R ± 2% (when necessary, the ambient temperature T A can be appropriately reduced) until the leakage current reaches the average current value and remains at this value without fluctuation for a long time. The corresponding ambient temperature is T A , and at this time, it can be considered that the Schottky diode has reached the junction temperature.

[0058] For example: Sample model: MBR10100H-5DL8, the T j of this Schottky diode is 175 °C, and the detection steps are as follows:

[0059] 1. Extract 5 samples and test them in an oven at 175 °C. Apply a reverse voltage V R = 100 V to the samples and test the leakage current value of I R1 at 175 °C (I R1 @ V R = 100 V). The specific data is as follows:

[0060] Serial number <![CDATA[I R1 @V R = 100V, 175 °C]]> 1 4.503 mA 2 4.589 mA 3 4.581 mA 4 4.542 mA 5 4.573 mA

[0061] The average current value of the five samples measured in this environment We consider it to be the leakage current value after the Schottky diode reaches T j , that is, when the leakage current of the Schottky diode reaches 4.5 mA, we consider that the Schottky diode is close to the junction temperature.

[0062] 2. Test the equivalent thermal resistance R ja of this Schottky diode in the corresponding HTRB test, which is about 120 °C / W.

[0063] 3. According to the conversion formula between the junction temperature and the ambient temperature T j = T A + P * R ja , The voltage V across the Schottky diode DUT = V R = 100 V, the ambient temperature T A of the test can be estimated as T j = T ja - P * R A = 175 - 100 × 0.0045 × 120 = 120.5 °C, that is, the ambient temperature T ASet at 120°C. Since HTRB is a steady-state test, the Schottky diode will generate its own power consumption during long-term power-on. If the Schottky diode is placed in an environment of 175°C for high-temperature reverse bias test, the internal leakage current of the Schottky diode will gradually increase, resulting in the internal temperature exceeding 175°C, thus causing thermal breakdown. Therefore, it is necessary to reduce the ambient temperature to ensure that the Schottky diode does not exceed T j 。

[0064] 4. In actual operation, due to the non-uniformity of the oven and the inconsistency of the products, when directly applying a 100V reverse voltage to the Schottky diode at an ambient temperature of 120°C, the Schottky diode I R may mutate greatly and cause super junction temperature burnout. Therefore, a 5KΩ resistor is connected in series at the front end of the Schottky diode. The function of this resistor is to prevent the Schottky diode from burning out due to overshoot. If the monitored leakage current I R of the Schottky diode suddenly increases, due to the series connection, this resistor R will divide part of the voltage of the Schottky diode, thus adjusting the voltage across the Schottky diode. However, due to the voltage division of the resistor R, the 100V voltage originally applied across the Schottky diode will suddenly drop to about 75V, and I R value also drops from 4.5mA to 1.8mA. At this time, manual pressure needs to be applied, and during the pressure application process, the change of I R across the Schottky diode needs to be constantly monitored. When I R reaches 3.85mA (85% of I R ), the pressure application time needs to be extended, and pressure is applied by 5% every 30 minutes. When I R reaches 4.5mA and the voltage across the Schottky diode is also measured to reach 100V, we consider that the Schottky diode has basically reached the junction temperature at this time.

[0065] The function of the series resistor R during the test is to divide the voltage of the Schottky diode when I R suddenly increases, preventing the Schottky diode I R from overshooting and causing thermal breakdown. The value of this resistor mainly depends on the value of I R of the Schottky diode in the junction temperature environment.

[0066] Generally recommended: When, R = 5kΩ;

[0067] When, R = 10kΩ;

[0068] The Schottky diode is extremely sensitive in the junction temperature environment. Therefore, during the entire HTRB test process, the accuracy of the ambient temperature T A must be guaranteed within ±2°C, and the heat dissipation of the Schottky diode is uniform.

[0069] The present invention solves the problem of thermal collapse or failure to reach junction temperature caused by leakage current mutation in traditional high-temperature reverse bias test by combining series resistor voltage division with dynamic temperature-voltage coordination. The core lies in: transient leakage current benchmark method: through the nominal junction temperature T j The following test determines the average current value As a benchmark for determining junction temperature; voltage divider protection mechanism: series resistor R suppresses leakage current I R Sudden change to prevent Schottky diode from overshoot failure; Closed-loop temperature control strategy: Combined with the ambient temperature T A The voltage across the Schottky diode V DUT Real-time adjustment ensures that the Schottky diode gradually approaches its nominal junction temperature in steady state. This method combines accuracy and practicality, making it particularly suitable for batch testing scenarios and significantly improving the reliability of high-temperature reverse-bias testing of Schottky diodes.

Claims

1. A method for verifying that the junction temperature of a Schottky diode reaches the specified value under high-temperature reverse bias, characterized in that: Including the following steps: Step 1. Transient leakage current reference test: Place multiple Schottky diode samples to be measured in a constant temperature environment with a nominal junction temperature T j , apply a reverse voltage V R , measure and record the leakage current values I R1 of each sample, and take the average current value as the reference value for determining the junction temperature; Step 2. Build a series voltage-dividing protection circuit: At room temperature, connect a resistor R in series at the front end of the diode under test. The resistance value of the resistor R is selected according to the average current value Selection: When is true, R = 5 kΩ ± 5%; When R = 10 kΩ ± 5%; Step 3. Dynamically coordinate temperature and pressure regulation, and adjust the voltage V across the Schottky diode according to the ambient temperature T A DUT ;​ Step 4. Junction temperature determination: Record the ambient temperature T at this time A , if it satisfies T j = T A + P × R ja , V DUT is the voltage across the Schottky diode, and R ja is the thermal resistance, then it is determined that the diode under test reaches the nominal junction temperature.

2. The method for verifying that the junction temperature is reached under high-temperature reverse bias of a Schottky diode according to claim 1, wherein : Step three specifically includes the following process, 3.1 Apply a reverse voltage V to the diode under test R , and increase the ambient temperature T at a rate of 1 - 3 °C / min A , and monitor the leakage current I in real time R ; 3.

2. When the ambient temperature T A reaches 0.6T j to 0.7T j , the heating rate of the ambient temperature T A is reduced to 0.5 - 1 °C / min; 3.

3. If the monitored leakage current I R increases, resulting in the voltage V DUT across the Schottky diode being lower than the reverse voltage V R , then the temperature increase T A is paused and the voltage V DUT across the Schottky diode is adjusted manually or automatically DUT to restore the voltage V R across the Schottky diode to the reverse voltage V ± 2%; 3.

4. Repeat step 3.3 until the monitored leakage current I R stabilizes at the average current value within the range and the duration is ≥ 30 minutes.

3. The method for verifying that the junction temperature is reached under high-temperature reverse bias of a Schottky diode according to claim 1, wherein : Reverse voltage V R ranges from 70% to 100% of the rated reverse voltage of the Schottky diode and needs to be lower than 80% of the breakdown voltage of the Schottky diode.

4. The method for verifying that the junction temperature is reached under high-temperature reverse bias of a Schottky diode according to claim 1, wherein: Thermal resistance R ja Measured by the steady-state power consumption method or the transient thermal impedance method, with an error range ≤ 10%.

5. The method for verifying that the junction temperature is reached under high-temperature reverse bias of a Schottky diode according to claim 1, wherein: The nominal junction temperature T j The constant temperature environment is provided by a high-precision oven. The temperature uniformity inside the oven is ≤ ±1 °C, and the temperature control accuracy is ≤ ±0.5 °C.

6. The method for verifying that the junction temperature is reached under high temperature reverse bias of a Schottky diode according to claim 1, characterized in that: Monitoring leakage current I R is measured using a high-precision microammeter with a resolution of ≤1 μA and a sampling frequency of ≥1 Hz.

7. The method for verifying that the junction temperature is reached under high-temperature reverse bias of a Schottky diode according to claim 1, wherein: The method is applicable to Schottky diodes with a junction temperature range of 125°C to 200°C.

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