A method for a pt sensor to monitor power diode junction temperature in real time in a powered up state

Abstract

This invention provides a method for real-time monitoring of the junction temperature of a power diode under powered conditions using a Pt sensor. The method comprises: S1: fabricating a Pt thin-film resistance temperature sensor on a copper-clad PCB; S2: determining the conversion coefficient M between the resistance and temperature of the Pt thin-film resistance temperature sensor; S3: fabricating a power diode with a Pt thin-film resistance temperature sensor at its bottom; S6: connecting the power diode to an aging circuit to monitor the resistance of the Pt thin-film resistance temperature sensor in real time, thereby monitoring the diode junction temperature under powered conditions using the Pt thin-film resistance temperature sensor. Compared to the thermocouple method, which can only test the surface temperature of the device, this invention offers better repeatability and uniformity of temperature measurement; compared to the infrared method, it does not need to consider the influence of the emissivity of the surface encapsulation material, resulting in more accurate chip junction temperature measurements; and compared to the thermal resistance test method, it eliminates the need for thermal resistance testing during diode powered-on testing, thus overcoming the limitation of traditional methods in real-time monitoring of diode junction temperature.

Description

Technical Field

[0001] This invention relates to detection technology in the field of power diodes, specifically to a method for real-time monitoring of the junction temperature of a power diode under powered conditions using a Pt sensor. Background Technology

[0002] Power diodes are widely used in aerospace products due to their low power consumption and long lifespan. During service, 70% of the input power of a power diode is converted into heat at the PN junction. This heat accumulates at the pads and interfaces, significantly reducing the diode's heat dissipation. Once the diode temperature rises to a certain level, the difference in thermal expansion coefficients between different materials can cause residual stress within the package structure, increasing the risk of diode failure such as breakage or delamination. Therefore, accurate measurement of the PN junction temperature of power diodes is crucial to prevent excessively high junction temperatures that could severely impact diode reliability.

[0003] Thermocouples are inexpensive and simple in structure, and are frequently used to measure the case temperature of power diodes, providing a direct contact method for sample surface temperature measurement. However, measuring a single temperature point requires one set of cables, and measuring multiple temperature points requires multiple sets of cables, making the operation complex and resulting in relatively poor measurement accuracy. Furthermore, thermocouples can only measure the surface temperature of diodes; for packaged power diodes, thermocouples cannot directly test the junction temperature of the diode chip. Only by breaking the diode case can direct temperature measurement of the diode chip surface be achieved using thermocouples, failing to meet the requirements of non-destructive testing. Even when using thermocouples to test the chip surface temperature, the thermocouple probes may crush the fragile chip, leading to inaccurate junction temperature measurements.

[0004] Infrared spectroscopy can quickly and intuitively obtain the temperature distribution on the surface of a power diode without requiring contact with the sample surface, making it a non-contact temperature measurement method. However, different sample surfaces have different emissivity, requiring calibration of the sample surface temperature and the emissivity of the surface material for each measurement. Furthermore, infrared spectroscopy only obtains the temperature of the sample surface; therefore, to perform temperature testing on a power diode chip, the diode must be unpacked.

[0005] Traditional thermal resistance (RTR) is also a non-contact temperature measurement method, which indirectly calculates the diode's junction temperature by leveraging the correlation between the diode's electrical parameters and temperature. While this method can accurately obtain the diode junction temperature, it requires complex and expensive testing equipment. For manufacturers engaged in mass production and testing, it is not a simple, fast, or low-cost way to monitor the PN junction temperature of chips. Furthermore, traditional RRT cannot be used to test the PN junction temperature of a diode under power, as the testing equipment may severely affect the diode under power, potentially burning or damaging it. Therefore, traditional RRT cannot monitor the diode junction temperature in real time; the junction temperature can only be measured after the diode is powered off. However, the junction temperature measured under power-off conditions differs from that under power-on conditions, making accurate assessment of the junction temperature impossible.

[0006] In summary, the thermocouple method, infrared method, and traditional thermal resistance method cannot independently, accurately, and in real-time monitor the junction temperature of a power diode under powered conditions. A new testing method needs to be developed to accurately and in real-time monitor the junction temperature of the diode under powered aging conditions. Summary of the Invention

[0007] The purpose of this invention is to provide a method for real-time monitoring of the junction temperature of a power diode under powered conditions using a Pt sensor, thereby solving the problem that existing technologies cannot independently and accurately monitor the junction temperature of a power diode under powered conditions in real time.

[0008] To achieve the above objectives, the present invention provides a method for real-time monitoring of the junction temperature of a power diode under powered conditions using a Pt sensor, characterized by the following steps: S1: fabricating a Pt thin-film resistance temperature sensor on a PCB copper-clad board to obtain a PCB copper-clad board with a Pt thin-film resistance temperature sensor; S2: determining the conversion factor M between the resistance and temperature of the Pt thin-film resistance temperature sensor; S3: fabricating a power diode with a Pt thin-film resistance temperature sensor on the bottom of the chip; S6: connecting the power diode to an aging circuit to monitor the resistance of the Pt thin-film resistance temperature sensor in real time, converting it to the Pt thin-film resistance temperature sensor temperature Tr according to the conversion factor M, thereby monitoring the diode junction temperature under powered conditions using the Pt thin-film resistance temperature sensor.

[0009] Furthermore, between S3 and S6, the following steps are included: S4: Connect the power diode to the transient thermal resistance test circuit, then place it in a constant temperature oil bath, and use a T3ster device to measure the temperature sensitivity parameter K coefficient of the diode chip; S5: Heat the power diode through a heating tube and maintain the temperature, drive the power diode with the heating current of the T3ster, monitor the resistance of the Pt thin film resistance temperature sensor in real time using a resistance meter, determine the Pt thin film resistance temperature sensor temperature Tr through the resistance of the Pt thin film resistance temperature sensor and the above-mentioned conversion M coefficient, then measure the junction temperature Tj of the diode chip through the T3ster transient thermal resistance method and the above-mentioned K coefficient, change the heating tube temperature individually, obtain a series of Pt thin film resistance temperature sensor temperatures Tr and diode chip junction temperatures Tj, thereby obtaining the temperature fitting relationship between the two;

[0010] Furthermore, in S6, after converting the Pt thin-film resistance temperature sensor temperature Tr according to the conversion M coefficient, the junction temperature of the diode chip is obtained by combining the temperature fitting curve.

[0011] Furthermore, the Pt thin film resistance temperature sensor is a Pt layer with Ti as the bonding substrate, including rectangular positive electrode pad areas and negative electrode pad areas at both ends, and a middle ribbon cable area with a serpentine distribution. The resistance of the middle ribbon cable area is the resistance of the Pt thin film resistance temperature sensor.

[0012] Furthermore, step S1 includes: covering the PCB copper-clad board with a Pt thin film resistance temperature sensor mask, selectively depositing Ti layer and Pt layer sequentially according to the required shape of the Pt thin film resistance temperature sensor, removing the Pt thin film resistance temperature sensor mask after the deposition is completed, and forming a Pt thin film resistance temperature sensor with Ti as the bonding underlayer in the area not covered by the Pt thin film resistance temperature sensor mask.

[0013] Furthermore, step S2 includes: measuring the resistance of the Pt thin-film resistance temperature sensor using a resistance meter, and monitoring the temperature of the Pt thin-film resistance temperature sensor using a thermocouple sensor; heating the copper-clad PCB board and plotting the resistance r of the Pt thin-film resistance temperature sensor at different temperatures. l Pt thin film resistance temperature sensor temperature t l The curve is plotted, where l = 1, 2, ..., S, and S is the number of heating temperature points. The conversion factor M between the resistance and temperature of the Pt thin film resistive temperature sensor is determined.

[0014] Furthermore, step S3 includes: covering the PCB copper-clad board with the Pt thin-film resistance temperature sensor using a silicone mask, selectively coating it with high thermal conductivity insulating silicone; fixing the diode chip on the upper surface of the silicone to ensure that the Pt thin-film resistance temperature sensor is located below the diode chip, allowing the silicone to cure and bond the chip; soldering the diode leads to the area on the PCB copper-clad board surface not covered by the Pt thin-film resistance temperature sensor, and bonding the chip surface pads and the diode leads together; and injection molding to obtain a power diode with a Pt thin-film resistance temperature sensor on the bottom of the chip.

[0015] Furthermore, the silicone completely covers the central ribbon cable area of ​​the Pt thin-film resistance temperature sensor, and partially covers the positive electrode pad area, negative electrode pad area, and PCB copper-clad board of the Pt thin-film resistance temperature sensor. The central ribbon cable area of ​​the Pt thin-film resistance temperature sensor is located below the diode chip.

[0016] Furthermore, step S4 includes: placing the power diode connected to the transient thermal resistance test circuit into a constant temperature oil bath, adjusting the oil temperature to raise the PN junction temperature of the diode chip, recording the PN junction voltage drop-junction temperature curve in real time, and determining the temperature-sensitive parameter K coefficient.

[0017] Furthermore, in step S5, T3ster uses the maximum heating current to drive the power diode and obtains the temperature fitting relationship between the chip junction temperature Tj and the Pt thin-film resistance temperature sensor temperature Tr, Tj = k max *Tr+b max .

[0018] Furthermore, the thickness of the Ti layer ranges from 5 to 20 nm, the thickness of the Pt layer ranges from 300 to 1000 nm, and / or the copper-clad laminate of the PCB is replaced with a ceramic substrate or a metal substrate.

[0019] Compared with the prior art, the beneficial effects of the present invention include:

[0020] Compared to the thermocouple method, which can only test the surface temperature of the device, the temperature measurement point of the Pt thin film resistance temperature sensor of this invention is located directly below the chip, resulting in better repeatability and uniformity of temperature measurement. Compared to the infrared method, this invention does not need to consider the influence of the emissivity of the surface encapsulation material, resulting in more accurate chip junction temperature measurements. Compared to thermal resistance testing methods that require complex connections and are costly, this invention only needs to perform transient thermal resistance testing when the linear relationship between the junction temperature and the Pt thin film resistance temperature sensor temperature is determined, and thermal resistance testing is not required during diode power-on testing, thus solving the problem that traditional junction temperature testing methods cannot monitor diode junction temperature in real time. Attached Figure Description

[0021] The method for real-time monitoring of the junction temperature of a power diode under powered conditions using a Pt sensor according to the present invention is given by the following embodiments and figures.

[0022] Figure 1 This is a flowchart illustrating a preferred embodiment of the method for real-time monitoring of the junction temperature of a power diode using a Pt sensor under powered conditions.

[0023] Figure 2 This is a schematic diagram of a Pt thin film resistive temperature sensor deposited on the surface of a copper-clad PCB according to a preferred embodiment of the present invention.

[0024] Figure 3 This is a schematic diagram of the Pt thin film resistance temperature sensor electrode leads mounted on the surface of the Pt thin film resistance temperature sensor according to a preferred embodiment of the present invention.

[0025] Figure 4 This is a schematic diagram illustrating the measurement of the resistance and temperature conversion M coefficient of a Pt thin film resistive temperature sensor according to a preferred embodiment of the present invention.

[0026] Figure 5 This is a graph showing the resistance and temperature curves of a Pt thin-film resistor temperature sensor according to a preferred embodiment of the present invention.

[0027] Figure 6 This is a schematic diagram illustrating the selective coating of highly thermally conductive insulating silicone onto the surfaces of a Pt thin-film resistance temperature sensor and a PCB copper-clad laminate, representing a preferred embodiment of the present invention.

[0028] Figure 7 This is a schematic diagram of a diode chip fixedly mounted on a high thermal conductivity insulating silicone surface according to a preferred embodiment of the present invention;

[0029] Figure 8 This is a schematic diagram of a preferred embodiment of the present invention showing the diode leads mounted on the surface of a PCB copper-clad laminate.

[0030] Figure 9 This is a schematic diagram of the bonding connection between the diode chip and the diode lead-out terminal according to a preferred embodiment of the present invention;

[0031] Figure 10 This is a schematic diagram of a diode sample injection molding cap according to a preferred embodiment of the present invention;

[0032] Figure 11 A schematic diagram illustrating the determination of the diode temperature-sensitive parameter K coefficient using the transient thermal resistance method according to a preferred embodiment of the present invention;

[0033] Figure 12 This is a schematic diagram illustrating the preferred embodiment of the present invention for determining the temperature of a Pt thin film resistance temperature sensor using the calibration resistance method and testing the junction temperature of a diode chip using the transient thermal resistance method.

[0034] Figure 13The transient thermal resistance method chip junction temperature and the temperature curve of the Pt thin film resistance temperature sensor measured under a heating current of 0.2A, which is a preferred embodiment of the present invention;

[0035] Figure 14 This is a superimposed graph of the junction temperature of a transient thermal resistance chip driven by different heating currents and the temperature curves of a Pt thin film resistance temperature sensor driven by a calibration resistance method, representing a preferred embodiment of the present invention.

[0036] Figure 15 This is a schematic diagram illustrating how the junction temperature of the diode chip is inferred from the temperature of the Pt thin film resistance temperature sensor during the aging process, which is a preferred embodiment of the present invention. Detailed Implementation

[0037] The following will combine Figures 1-15 The method for real-time monitoring of the junction temperature of a power diode under powered conditions using a Pt sensor according to the present invention will be described in further detail.

[0038] This invention solves the problem that existing technologies cannot independently, accurately, and in real-time monitor the junction temperature of power diodes under powered conditions. Figure 1 This is a schematic flowchart illustrating a preferred embodiment of the method for real-time monitoring of the junction temperature of a power diode under powered conditions. See also... Figure 1 The method for real-time monitoring of the junction temperature of a power diode under powered conditions according to an embodiment of the present invention includes the following steps: S1: Prepare a Pt thin-film resistance temperature sensor on a PCB copper-clad board to obtain a PCB copper-clad board with a Pt thin-film resistance temperature sensor; S2: Determine the conversion coefficient M between the resistance and temperature of the Pt thin-film resistance temperature sensor; S3: Prepare a power diode with a Pt thin-film resistance temperature sensor on the bottom of the chip; S4 (optional): Connect the power diode to a transient thermal resistance test circuit, then place it in a constant temperature oil bath, and use a T3ster device to measure the temperature sensitivity parameter K coefficient of the diode chip; S5 (optional): Heat the power diode through a heating tube and maintain the temperature, drive the power diode with the heating current of the T3ster, monitor the resistance of the Pt thin-film resistance temperature sensor in real time using a resistance meter, determine the Pt thin-film resistance temperature sensor temperature Tr through the resistance of the Pt thin-film resistance temperature sensor and the above-mentioned conversion coefficient M, and then determine the junction temperature Tj of the diode chip through the T3ster transient thermal resistance method and the above-mentioned K coefficient, change the temperature of the heating tube alone, obtain a series of Pt thin-film resistance temperature sensor temperatures Tr and diode chip junction temperatures Tj, thereby obtaining the temperature fitting relationship between the two.

[0039] S6: Connect the power diode to the aging circuit, monitor the resistance of the Pt thin film resistance temperature sensor in real time, convert the resistance to the Pt thin film resistance temperature sensor temperature Tr according to the conversion factor M, and obtain the junction temperature of the diode chip (optional) by combining the temperature fitting curve. Thus, the junction temperature of the diode under the power-on state is monitored by the Pt thin film resistance temperature sensor.

[0040] The various steps of the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

[0041] S1: Conversion of M coefficients for Pt thin film resistance temperature sensor fabrication on PCB copper-clad board.

[0042] Pt thin-film resistance temperature sensors are a type of metal thin-film resistance temperature sensor. Their basic principle is based on the thermal effect of metal thin-film resistance for temperature measurement; that is, the resistance of the metal thin-film resistor changes with temperature. By measuring the change in resistance of the temperature-sensing metal thin-film resistor, the temperature can be measured. Figure 2 This is a schematic diagram of a Pt thin film resistive temperature sensor deposited on the surface of a copper-clad PCB according to a preferred embodiment of the present invention. Figure 2 First, a Pt thin-film resistance temperature sensor mask 112 of a specific shape is used to cover the PCB copper-clad board 111. A Ti layer with a thickness range of 5-20 nm is selectively deposited on the surface of the PCB copper-clad board 111 as the bottom layer to improve the bonding strength. Then, a Pt layer with a thickness range of 300-1000 nm is selectively deposited in the same area as the surface layer to completely cover the Ti layer. After the deposition is completed, the Pt thin-film resistance temperature sensor mask 112 is removed. The area not covered by the Pt thin-film resistance temperature sensor mask 112 will form a Pt thin-film resistance temperature sensor with Ti as the bonding bottom layer.

[0043] The Pt thin-film resistance temperature sensor includes rectangular positive electrode pad areas 113 and negative electrode pad areas 114 at both ends, and a serpentine distribution of intermediate wiring area 115. The resistance of the intermediate wiring area 115 is the resistance of the Pt thin-film resistance temperature sensor. The serpentine distribution of the intermediate wiring area 115 is designed to increase the contact area with the diode chip, improve the temperature measurement stability of the Pt thin-film resistance temperature sensor, and reduce the chip junction temperature measurement error.

[0044] The Pt thin-film resistance temperature sensor has a serpentine shape. This serpentine shape can be the pointed serpentine structure shown in the accompanying drawings, or other serpentine structures commonly found in the art, such as a serpentine with a 180-degree turn or a serpentine with arc segments. The specific shape can be determined according to actual needs; any serpentine shape falls within the scope of this invention. The serpentine shape increases the contact area with the silicone substrate on the chip, improving temperature measurement accuracy and ensuring precise measurement of the chip's bottom temperature through contact.

[0045] Furthermore, Pt thin-film resistance temperature sensors can also be designed in other shapes, but these require layout design and involve complex fabrication processes. This invention only selects the simplest serpentine distribution pattern. Those skilled in the art can, based on the teachings of this invention, explore other suitable shapes.

[0046] Figure 3 This is a schematic diagram showing the surface-mounted electrode leads of a Pt thin-film resistance temperature sensor according to a preferred embodiment of the present invention. Figure 3 The positive electrode 116 and negative electrode 117 of the Pt thin film resistance temperature sensor are soldered to the positive electrode pad area 113 and negative electrode pad area 114 of the Pt thin film resistance temperature sensor, respectively, by using tin-lead solder heated by a soldering iron.

[0047] S2: Determine the conversion factor M between resistance and temperature of the Pt thin film resistive temperature sensor.

[0048] The relationship between resistance and temperature of a Pt thin-film resistive temperature sensor was determined and used as the conversion factor M.

[0049] Figure 4 This is a schematic diagram illustrating the determination of the resistance and temperature conversion coefficient (M) of a Pt thin-film resistive temperature sensor according to a preferred embodiment of the present invention. Figure 4 The resistance gauge 121 of the Pt thin-film resistance temperature sensor is connected to the positive terminal 116 and the negative terminal 117 of the Pt thin-film resistance temperature sensor electrode leads, respectively. The resistance of the Pt thin-film resistance temperature sensor is measured through the resistance gauge 121. The thermocouple sensor 119 is made in close contact with the Pt thin-film resistance temperature sensor wiring area 115. The temperature of the Pt thin-film resistance temperature sensor wiring area 115 is monitored by the thermocouple sensor temperature gauge 120 and used as the temperature of the Pt thin-film resistance temperature sensor.

[0050] Heating tube 118 is used to heat the PCB copper-clad board 111. Once the reading on the thermocouple sensor temperature gauge 120 no longer changes significantly, the resistance value measured by the Pt thin-film resistance temperature sensor resistance gauge 121 and the temperature of the Pt thin-film resistance temperature sensor measured by the thermocouple sensor temperature gauge 120 are determined. The temperature of heating tube 118 is kept constant at 20, 40, 80, and 100℃, and the resistances (r1, r2, r3, r4) measured by the Pt thin-film resistance temperature sensor resistance gauge 121 and the temperatures (t1, t2, t3, t4) measured by the thermocouple sensor temperature gauge 120 are recorded respectively. Heating tube 118 is removed after the test.

[0051] Figure 5This is a graph showing the resistance and temperature curves of a Pt thin-film resistor-temperature sensor according to a preferred embodiment of the present invention. Figure 5 A graph showing the resistance versus temperature of a Pt thin-film resistor temperature sensor was plotted. The curve exhibits a linear relationship, allowing the determination of the conversion factor M between the resistance and temperature of the Pt thin-film resistor temperature sensor. Based on this conversion factor M, the temperature t of the Pt thin-film resistor temperature sensor can be obtained once the resistance r of the sensor is known.

[0052] S3: Fabricate a power diode with a Pt thin-film resistance temperature sensor on the bottom of the chip.

[0053] Figure 6 This is a schematic diagram illustrating the selective coating of highly thermally conductive insulating silicone onto the surfaces of a Pt thin-film resistance temperature sensor and a PCB copper-clad laminate, representing a preferred embodiment of the present invention. Figure 6 A silicone mask 122 of a specific shape is used to cover the PCB copper-clad board with the Pt thin-film resistance temperature sensor obtained in step S1. Then, a high thermal conductivity insulating silicone 123 with a thickness of approximately 500 μm is selectively coated, with the silicone coating area approaching the area of ​​the diode chip. This silicone layer completely covers the central ribbon cable area 115 of the Pt thin-film resistance temperature sensor and partially covers the positive electrode pad area 113, the negative electrode pad area 114, and the PCB copper-clad board 111 of the Pt thin-film resistance temperature sensor. After coating, the silicone mask 122 is removed.

[0054] Figure 7 This is a schematic diagram illustrating the surface mounting of a diode chip on a high thermal conductivity insulating silicone surface according to a preferred embodiment of the present invention. Figure 7 The diode chip 124 is fixedly mounted on the upper surface of the high thermal conductivity insulating silicone 123, ensuring that the middle ribbon cable area 115 of the Pt thin film resistance temperature sensor is located below the diode chip 124. This can be achieved by heating the PCB copper-clad laminate 111 using, for example, a heating tube 118, to cure the high thermal conductivity insulating silicone 123 and bond the diode chip 124. After the silicone has cured, the heating tube 118 is removed, and a probe is used to test the resistance between the positive electrode 125 (or negative electrode 126) of the diode chip surface pad and the positive electrode pad area 113 (or negative electrode pad area 114) of the Pt thin film resistance temperature sensor. If the resistance is high, it indicates that the diode chip and the Pt thin film resistance temperature sensor are insulated and not electrically conductive, meeting the process requirements.

[0055] The high thermal conductivity insulating silicone 123 not only allows the heat generated by the diode chip 124 to be quickly conducted to the intermediate wiring area 115 of the Pt thin-film resistance temperature sensor, but also prevents mutual electrical conduction between the diode chip 124 and the Pt thin-film resistance temperature sensor wiring area 115. After coating with the high thermal conductivity insulating silicone 123, when the diode chip 124 is turned on under high current, the temperature of the Pt thin-film resistance temperature sensor wiring area 115 will also change directionally when the junction temperature of the diode chip 124 changes.

[0056] Figure 8 This is a schematic diagram of a diode lead mounted on the surface of a copper-clad PCB according to a preferred embodiment of the present invention. Figure 8 The positive terminal 128 and the negative terminal 129 of the diode are soldered onto the area of ​​the PCB copper-clad board 111 that is not covered by the Pt thin film resistance temperature sensor using tin-lead solder heated by a soldering iron.

[0057] Figure 9 This is a schematic diagram illustrating the bonding connection between the diode chip and the diode leads according to a preferred embodiment of the present invention. Figure 9 The positive terminal 125 of the diode chip surface pad and the positive terminal 128 of the diode lead are bonded together, and the negative terminal 126 of the diode chip surface pad and the negative terminal 129 of the diode lead are bonded together.

[0058] Figure 10 This is a schematic diagram of a diode sample injection-molded cap according to a preferred embodiment of the present invention. Figure 10 The diode sample is injection molded to form a plastic-encapsulated housing 130. The side of the housing contains a positive electrode 116 and a negative electrode 117 of the Pt thin-film resistance temperature sensor electrode, as well as a positive electrode 128 and a negative electrode 129 of the diode, thus obtaining a power diode with a Pt thin-film resistance temperature sensor on the bottom of the chip.

[0059] S4: Connect the power diode to the transient thermal resistance test circuit, then place it in a constant temperature oil bath, and use a T3ster device to measure the temperature sensitivity parameter K coefficient of the diode chip.

[0060] Figure 11 This is a schematic diagram illustrating the transient thermal resistance method for determining the K coefficient of a diode, a preferred embodiment of the present invention. Figure 11A power diode is connected to the transient thermal resistance test circuit. The positive terminal 128 of the diode is connected to the positive terminals of the VF voltage sensor 140, the IM test current 141, and the IH heating current 142, respectively. The negative terminal 129 of the diode is connected to the negative terminals of the same three devices. Since the actual directions of the VF voltage sensor 140, the IM test current 141, and the IH heating current 142 are the same, all three will display positive values ​​(+).

[0061] The entire power diode is placed in a constant-temperature oil bath 135 and kept there for a certain period of time until the temperature of the constant-temperature oil 136 is equal to the PN junction temperature of the power diode. The temperature of the constant-temperature oil 136 is adjusted so that the PN junction temperature of the power diode is gradually increased from 25°C to 140°C at a heating rate of 5°C / minute.

[0062] A T3ster device was used to apply a 5mA IM test current 141 to the power diode, without applying an IH heating current 142. A VF voltage sensor 140 was used to monitor the change in PN junction voltage drop across the diode's positive terminal 128 and negative terminal 129 in real time. The PN junction voltage drop-junction temperature curve of the power diode was recorded in real time to determine its temperature-sensitive parameter K coefficient.

[0063] After the test, clean the oil off the surface of the power diode.

[0064] S5: The power diode is heated by a heating tube and its temperature is maintained. The power diode is driven by the heating current of T3ster. The resistance of the Pt thin film resistance temperature sensor is monitored in real time by a resistance meter. The temperature Tr of the Pt thin film resistance temperature sensor is determined by the resistance of the Pt thin film resistance temperature sensor and the above-mentioned conversion M coefficient. Then, the junction temperature Tj of the diode chip is determined by the T3ster transient thermal resistance method and the above-mentioned K coefficient. The temperature of the heating tube is changed individually to obtain a series of Pt thin film resistance temperature sensor temperatures Tr and diode chip junction temperatures Tj. Thus, the temperature fitting relationship between the two is obtained.

[0065] Figure 12This diagram illustrates the preferred embodiment of the present invention for determining the temperature of a Pt thin-film resistance temperature sensor using the calibration resistance method and testing the junction temperature of a diode chip using the transient thermal resistance method. The calibration resistance method for determining the Pt thin-film resistance temperature sensor temperature includes: driving a power diode with a heating current to raise the chip junction temperature until it reaches a stable state; using a resistance meter to monitor the resistance of the Pt thin-film resistance temperature sensor in real time, and using the conversion coefficient M between the Pt thin-film resistance temperature sensor resistance and temperature to monitor the Pt thin-film resistance temperature sensor temperature Tr in real time; the transient thermal resistance method for testing the diode chip junction temperature includes: determining the diode chip temperature-sensitive parameter K coefficient; driving a power diode with a heating current to raise the chip junction temperature until it reaches a stable state; rapidly switching the heating current to the test current; monitoring the PN junction voltage drop curve in real time using a voltage sensor; and obtaining the chip junction temperature Tj using the K coefficient.

[0066] like Figure 12 Connect the power diode to the transient thermal resistance test circuit. Connect the positive terminal 128 (or negative terminal 129) of the diode to the positive (or negative) terminals of the VF voltage sensor 140, IM test current 141, and IH heating current 142, respectively. Connect the Pt thin-film resistance temperature sensor dial 121 to the positive terminal 116 and the negative terminal 117 of the Pt thin-film resistance temperature sensor electrode of the power diode, respectively. Monitor the resistance of the Pt thin-film resistance temperature sensor through the Pt thin-film resistance temperature sensor dial 121.

[0067] By individually changing the heating element temperature, the linear relationship between the junction temperature and the Pt thin-film resistance temperature sensor temperature can be verified and obtained. This includes: individually changing the heating element temperature while driving the power diode with the same heating current to change the chip junction temperature; and monitoring the Pt thin-film resistance temperature sensor temperature Tr at each temperature point using the calibration resistor method. i (i = 1, 2, ..., N, where N is the number of temperature measurement points), the chip junction temperature Tj is measured using the transient thermal resistance method. i (i = 1, 2, ..., N, where N is the number of temperature measurement points); the transient thermal resistance chip junction temperature Tj under the same heating current is measured. i (i = 1, 2, ..., N) and the temperature Tr of the Pt thin film resistance temperature sensor calibrated by resistance method i (i = 1, 2, ..., N) are plotted as curve x1.

[0068] If the transient thermal resistance chip junction temperature Tj and the calibration resistance Pt thin film resistance temperature sensor temperature Tr in curve x1 are... i If a linear relationship is observed, the relationship Tj = k1*Tr + b1 can be obtained through linear fitting, indicating that this linear relationship is not affected by ambient temperature.

[0069] The power diode is heated by heating tube 118, which keeps the temperature of the heating tube at 20°C.

[0070] A 0.2A IH heating current 142 is used to drive the power diode to raise the chip junction temperature. After the chip PN junction voltage drop measured by the VF voltage sensor 140 of the T3ster device stabilizes, the resistance of the Pt thin film resistance temperature sensor is monitored in real time using the resistance instrument panel 121. The temperature Tr1 of the Pt thin film resistance temperature sensor is monitored in real time by calibrating with the above-mentioned conversion M coefficient.

[0071] The IH heating current 142 of T3ster is quickly switched to the IM test current 141. At the same time, the VF voltage sensor 140 is used to monitor the change curve of the PN junction voltage drop of the power diode in real time. The junction temperature Tj1 of the diode chip under the action of 0.2A IH heating current 142 is obtained through the K coefficient in step S30.

[0072] By changing the temperature of heating tube 118 and repeating the test, the junction temperature Tj of the diode chip and the temperature Tr of the Pt thin film resistance temperature sensor were plotted. The curves showed a linear relationship and were not affected by the ambient temperature.

[0073] Specifically, the heating tube temperature was maintained at 40, 60, and 80°C, respectively, and a 0.2A IH heating current 142 was used to drive the power diode to change the chip junction temperature. At each temperature point, the above test steps were repeated, and the Pt thin film resistance temperature sensor temperature (Tr2, Tr3, Tr4) was monitored using the calibration resistor method, and the junction temperature (Tj2, Tj3, Tj4) of the diode chip 124 was tested using the transient thermal resistance method.

[0074] Figure 13 The transient thermal resistance chip junction temperature and the temperature curve of the calibration resistance Pt thin film resistance temperature sensor measured under a heating current of 0.2A, according to a preferred embodiment of the present invention, are shown in curve x1. Curve x1 plots the transient thermal resistance chip junction temperature (Tj1, Tj2, Tj3, Tj4) and the calibration resistance Pt thin film resistance temperature sensor temperature (Tr1, Tr2, Tr3, Tr4) under a heating current of 0.2A IH 142. Figure 13 In curve x1, the transient thermal resistance chip junction temperature Tj and the calibration resistance Pt thin-film resistance temperature sensor temperature Tr exhibit a linear relationship. Linear fitting yields the equation Tj = k1*Tr + b1, indicating a highly high correlation between the transient thermal resistance chip junction temperature and the calibration resistance Pt thin-film resistance temperature sensor temperature under different ambient temperatures, and this linear relationship is unaffected by ambient temperature. Because the heat generated by the diode chip 124 is transferred to the bottom Pt thin-film resistance temperature sensor due to the thermal resistance of the thermally conductive silicone, the Pt thin-film resistance temperature sensor temperature is lower than that of the diode chip 124.

[0075] In actual testing, since the temperature of the Pt thin-film resistance temperature sensor is lower than the temperature of the diode chip 124, when an accurate temperature of the diode chip 124 is not required, the temperature of the diode chip 124 can be roughly determined by the temperature of the Pt thin-film resistance temperature sensor, and the temperature of the diode chip 124 can be controlled to prevent it from becoming too high. Therefore, steps S4 and S5 are omitted in the method.

[0076] In addition, the maximum chip junction temperature Tj can be obtained from the diode product manual. max Inverse determination of maximum Pt thin film resistance temperature sensor temperature Tr max Then, the maximum resistance R of the Pt thin-film temperature sensor is determined by converting the M coefficient. max This prevents the diode chip 124 from burning out due to overheating by avoiding the Pt thin-film resistor temperature sensor resistance from exceeding a critical value.

[0077] In addition, to obtain optimal experimental conditions, the following experiment was conducted, and the experimental principle is as follows:

[0078] The linear relationship between the junction temperature and the temperature of the Pt thin-film resistance temperature sensor was verified by individually changing the heating current of the T3ster. This included: individually changing the heating current of the T3ster to drive the power diode and thus change the chip junction temperature; and determining the transient thermal resistance method junction temperature Tj under each heating current. i (i = 1, 2, ..., N) and the temperature Tr of the Pt thin film resistance temperature sensor calibrated by resistance method i (i = 1, 2, ..., N) Curve x z (z = 1, 2, ..., M, where M is the heating current). If each curve x z In the range (z = 1, 2, ..., M), both the transient thermal resistance chip junction temperature Tj and the calibration resistance Pt thin-film resistance temperature sensor temperature Tr exhibit a linear relationship. Therefore, through linear fitting, the relationship Tj = k z *Tr+b z (z = 1, 2, ..., M). Furthermore, the curves x... z Superimpose (z = 1, 2, ..., M) curves and determine their linear correlation and overlap. Calculate the slope correlation p of each curve separately. z (z = 1, 2, ..., M-1) and intercept correlation q z (z=1,2,┄,M-1), if all are less than or equal to 5%, it indicates that the linear relationship is not affected by the driving heating current.

[0079] Experiment 1

[0080] By changing the heating current of T3ster and repeating step S5, the junction temperature Tj of the diode chip and the temperature Tr of the Pt thin film resistance temperature sensor under different heating currents are superimposed. The curves have good overlap and the linear relationship is not affected by the driving heating current.

[0081] The power diodes were driven with IH heating currents of 0.4A, 0.6A, and 0.8A respectively to raise the chip junction temperature. Step S5 was repeated to determine the transient thermal resistance chip junction temperature Tj and the calibration resistance Pt thin film resistance temperature sensor temperature Tr curves x2, x3, and x4 under the heating currents of 0.4A, 0.6A, and 0.8A respectively. The transient thermal resistance chip junction temperature Tj and the calibration resistance Pt thin film resistance temperature sensor temperature Tr in curves x2, x3, and x4 also showed a linear relationship. Through linear fitting, the relationships Tj = k2*Tr + b2, Tj = k3*Tr + b3, and Tj = k4*Tr + b4 were obtained.

[0082] Experiment 1 revealed that: the larger the IH heating current 142 (current corresponding to curve x4 0.8A > current corresponding to curve x3 0.6A > current corresponding to curve x2 0.4A > current corresponding to curve x1 0.2A), the higher the junction temperature of diode chip 124; the larger the IH heating current 142, the more convergent the corresponding curves. For example, curves x4 and x3 have a higher degree of convergence (higher curve similarity, higher similarity of the fitted curve formula, and more accurate fitted curve formula), curves x3 and x2 have a lower degree of convergence (lower curve similarity, lower similarity of the fitted curve formula, and lower accuracy of the fitted curve formula), and curves x2 and x1 have the lowest degree of convergence compared to the former two (worst curve similarity, worst similarity of the fitted curve formula, and worst accuracy of the fitted curve formula). Therefore, the larger the IH heating current 142, the more convergent the corresponding curves, and the more accurate the fitted curve formula obtained, i.e., the accuracy of the curve formula is x4 > x3 > x2 > x1.

[0083] Figure 14 This is a superimposed graph of the transient thermal resistance chip junction temperature and the temperature curves of the Pt thin film resistance temperature sensor driven by different heating currents, representing a preferred embodiment of the present invention. The transient thermal resistance chip junction temperature and the temperature curves (x1, x2, x3, x4) of the Pt thin film resistance temperature sensor driven by different heating currents (0.2A, 0.4A, 0.6A, and 0.8A) are superimposed to obtain the superimposed graph of the temperature curves of the transient thermal resistance chip junction temperature and the Pt thin film resistance temperature sensor driven by different heating currents, as shown below. Figure 14The linear correlation and overlap of x1, x2, x3, and x4 are all high. The slope correlation (p1, p2, and p3) and intercept correlation (q1, q2, and q3) of each curve were calculated, where p1 = (k1-k2) / k2, p2 = (k1-k3) / k3, p3 = (k1-k4) / k4, and q1 = (b1-b2) / b2, q2 = (b1-b3) / b3, q3 = (b1-b4) / b4. The slope correlation (p1, p2, p3) and intercept correlation (q1, q2, q3) are all less than or equal to 5%, indicating that the chip junction temperature measured by the transient thermal resistance method and the temperature of the Pt thin film resistance temperature sensor measured by the calibration resistance method also have extremely high correlation under different driving heating currents, indicating that this linear relationship is not affected by the driving heating current.

[0084] Furthermore, since a larger IH heating current 142 results in a higher junction temperature of diode chip 124, the obtained fitting curve formula is more accurate, and therefore the measured junction temperature of diode chip 124 is more accurate. Therefore, in step S5, it is preferable to use the maximum heating current of T3ster to drive the power diode.

[0085] The final step of the method of the present invention will be described below.

[0086] S6: Connect the power diode to the aging circuit and monitor the resistance of the Pt thin film resistance temperature sensor in real time. Convert the resistance to the Pt thin film resistance temperature sensor temperature Tr according to the conversion factor M. After performing steps S4 and S5, the junction temperature of the diode chip can also be obtained by combining the temperature fitting curve. Thus, the junction temperature of the power diode under the power-on state can be monitored by the Pt thin film resistance temperature sensor.

[0087] The diode is connected to the aging test circuit and powered on. The resistance of the Pt thin-film resistor temperature sensor is monitored in real time, and the Pt thin-film resistor temperature sensor temperature Tr is converted according to the conversion factor M. Combining the chip junction temperature and the Pt thin-film resistor temperature sensor temperature fitting curve under the maximum heating current, the diode chip junction temperature Tj is calculated in real time and quickly.

[0088] Figure 15 This is a schematic diagram illustrating how the junction temperature of the diode chip is inferred from the temperature of the Pt thin-film resistance temperature sensor during the aging process, as per a preferred embodiment of the present invention. Figure 15For power diodes with the same package structure and materials, the positive terminal 128 and the negative terminal 129 of the diode are connected to the aging test circuit 152, respectively. The positive terminal 116 and the negative terminal 117 of the Pt thin-film resistance temperature sensor electrode are connected to the Pt thin-film resistance temperature sensor resistance meter 121, respectively. During the aging test, the resistance of the Pt thin-film resistance temperature sensor is monitored in real time using the Pt thin-film resistance temperature sensor resistance meter 121. The converted chip bottom Pt thin-film resistance temperature sensor temperature Tr is obtained using the conversion factor M. Combined with the chip junction temperature and Pt thin-film resistance temperature sensor temperature fitting curve formula Tj=k under the maximum IH heating current 142, max *Tr+b max Rapidly monitor the junction temperature Tj of diode chip 124 in real time.

[0089] This invention has the following characteristics:

[0090] First, the thermocouple method can only obtain the surface temperature of the device through point contact each time, while the temperature measuring point of the Pt thin film resistance temperature sensor in this invention is located directly below the power diode chip, and the contact with the chip is surface contact with the chip with a larger contact area, resulting in better repeatability and uniformity of temperature measurement.

[0091] Secondly, the infrared method requires precise consideration of the emissivity of the diode surface encapsulation material and the influence of environmental conditions on the accuracy of temperature measurement. In this invention, the emissivity of the encapsulation material and environmental conditions have a smaller impact on the resistance test of the Pt thin film resistance temperature sensor, resulting in more accurate measurement of the chip junction temperature.

[0092] Third, traditional thermal resistance testing methods require specialized equipment with complex connections, resulting in low testing efficiency and high temperature measurement costs. This invention only requires thermal resistance testing when the linear relationship between the diode junction temperature and the Pt thin-film resistor temperature sensor temperature is established. Thermal resistance testing is unnecessary during diode aging and power-on processes, allowing for real-time monitoring of the diode junction temperature. This significantly improves temperature measurement efficiency and reduces testing costs. Furthermore, traditional thermal resistance methods cannot test the chip junction temperature of power diodes under aging and power-on conditions. This invention, however, only requires real-time monitoring of the resistance of the Pt thin-film resistor temperature sensor to indirectly calculate the chip junction temperature, and is not limited by whether the diode is under power-on conditions, thus broadening the testing applicability.

[0093] Fourth, in this invention, the Pt thin-film resistance temperature sensor and the diode chip are mutually insulated, avoiding damage to the diode chip during power-up. Simultaneously, the Pt thin-film resistance temperature sensor and the chip maintain high thermal conductivity, allowing the heat generated by the chip to be quickly transferred to the Pt thin-film resistance temperature sensor. The resistance value accurately reflects the chip junction temperature in real time, overcoming the limitation of existing methods that cannot measure junction temperature in real time.

[0094] Fifth, the Pt thin-film resistance temperature sensor of this invention can be fabricated not only on PCB copper-clad laminates, but also on ceramic substrates and metal substrates, and is not affected by the device packaging substrate, allowing for mass production of devices with various packaging types. This Pt thin-film resistance temperature sensor does not significantly alter the heat transfer path of the device, nor does it significantly increase the thermal resistance or dimensions of the device. For power diodes of the same packaging type, as long as the correspondence between the chip junction temperature and the resistance value of the Pt thin-film resistance temperature sensor is obtained, the chip junction temperature can be monitored simply and quickly, making it suitable for evaluating the heat dissipation reliability of diodes.

[0095] The above-described specific implementations can be partially adjusted by those skilled in the art in different ways without departing from the principles and purpose of the present invention. The scope of protection of the present invention is defined by the claims and is not limited to the above-described specific implementations. All implementation schemes within the scope of the claims are bound by the present invention.

Claims

1. A method for real-time monitoring of the junction temperature of a power diode under powered conditions using a Pt sensor, characterized in that, The process includes the following steps: S1: Fabricating a Pt thin-film resistance temperature sensor on a PCB copper-clad laminate to obtain a PCB copper-clad laminate with a Pt thin-film resistance temperature sensor; S2: Determine the conversion factor M between resistance and temperature for the Pt thin-film resistance temperature sensor; S3: Fabricate a power diode with a Pt thin-film resistance temperature sensor at the bottom of the chip; S6: Connect the power diode to the aging circuit, monitor the resistance of the Pt thin film resistance temperature sensor in real time, convert it to the Pt thin film resistance temperature sensor temperature Tr according to the conversion factor M, and thus monitor the diode junction temperature under the power-on state through the Pt thin film resistance temperature sensor. Between S3 and S6, the following steps are further included: S4: Connect the power diode to the transient thermal resistance test circuit, then place it in a constant temperature oil bath, and use a T3ster device to measure the temperature sensitivity parameter K coefficient of the diode chip; S5: Heat the power diode through a heating tube and maintain the temperature, drive the power diode with the heating current of the T3ster, monitor the resistance of the Pt thin film resistance temperature sensor in real time using a resistance meter, determine the Pt thin film resistance temperature sensor temperature Tr through the resistance of the Pt thin film resistance temperature sensor and the above-mentioned conversion M coefficient, then measure the junction temperature Tj of the diode chip through the T3ster transient thermal resistance method and the above-mentioned K coefficient, change the temperature of the heating tube alone, obtain a series of Pt thin film resistance temperature sensor temperatures Tr and diode chip junction temperatures Tj, thereby obtaining the temperature fitting relationship between the two; Furthermore, in S6, after converting the Pt thin-film resistance temperature sensor temperature Tr according to the conversion M coefficient, the junction temperature of the diode chip is obtained by combining the temperature fitting curve.

2. The method for real-time monitoring of the junction temperature of a power diode under powered conditions using a Pt sensor as described in claim 1, characterized in that, The Pt thin-film resistance temperature sensor is a Pt layer with Ti as the bonding substrate, including rectangular positive electrode pad areas and negative electrode pad areas at both ends, and a middle ribbon cable area with a serpentine distribution. The resistance of the middle ribbon cable area is the resistance of the Pt thin-film resistance temperature sensor.

3. The method for real-time monitoring of the junction temperature of a power diode under powered conditions using a Pt sensor as described in claim 1, characterized in that, Step S1 includes: covering the PCB copper-clad board with a Pt thin film resistance temperature sensor mask, selectively depositing Ti layer and Pt layer sequentially according to the required shape of the Pt thin film resistance temperature sensor, removing the Pt thin film resistance temperature sensor mask after the deposition is completed, and forming a Pt thin film resistance temperature sensor with Ti as the bonding underlayer in the area not covered by the Pt thin film resistance temperature sensor mask.

4. The method for real-time monitoring of the junction temperature of a power diode under powered conditions using a Pt sensor as described in claim 1, characterized in that, Step S2 includes: measuring the resistance of the Pt thin-film resistance temperature sensor using a resistance meter, and monitoring the temperature of the Pt thin-film resistance temperature sensor using a thermocouple sensor; heating the copper-clad PCB board and plotting the resistance r of the Pt thin-film resistance temperature sensor at different temperatures. l Pt thin film resistance temperature sensor temperature t l The curve is plotted, where l = 1, 2, ..., S, and S is the number of heating temperature points. The conversion factor M between the resistance and temperature of the Pt thin film resistive temperature sensor is determined.

5. The method for real-time monitoring of the junction temperature of a power diode under powered conditions using a Pt sensor as described in claim 1, characterized in that, Step S3 includes: covering the PCB copper-clad board with the Pt thin-film resistance temperature sensor using a silicone mask, selectively coating it with high thermal conductivity insulating silicone; fixing the diode chip on the upper surface of the silicone to ensure that the Pt thin-film resistance temperature sensor is located below the diode chip, allowing the silicone to cure and bond the chip; soldering the diode leads to the area on the PCB copper-clad board surface not covered by the Pt thin-film resistance temperature sensor, and bonding the chip surface pads and the diode leads together; and injection molding to obtain a power diode with a Pt thin-film resistance temperature sensor at the bottom of the chip.

6. The method for real-time monitoring of the junction temperature of a power diode under powered conditions using a Pt sensor as described in claim 5, characterized in that, The silicone completely covers the central ribbon cable area of ​​the Pt thin film resistance temperature sensor, and partially covers the positive electrode pad area, negative electrode pad area, and PCB copper-clad board of the Pt thin film resistance temperature sensor. The central ribbon cable area of ​​the Pt thin film resistance temperature sensor is located below the diode chip.

7. The method for real-time monitoring of the junction temperature of a power diode under powered conditions using a Pt sensor as described in claim 1, characterized in that, Step S4 includes: placing the power diode connected to the transient thermal resistance test circuit into a constant temperature oil bath, adjusting the oil temperature to raise the PN junction temperature of the diode chip, recording the PN junction voltage drop-junction temperature curve in real time, and determining the temperature-sensitive parameter K coefficient.

8. The method for real-time monitoring of the junction temperature of a power diode under powered conditions using a Pt sensor as described in claim 1, characterized in that, In step S5, T3ster uses the maximum heating current to drive the power diode and obtains the temperature fitting relationship between the chip junction temperature Tj and the Pt thin-film resistance temperature sensor temperature Tr, Tj=k max ×Tr+b max .

9. The method for real-time monitoring of the junction temperature of a power diode under powered conditions using a Pt sensor as described in claim 3, characterized in that, The thickness of the Ti layer ranges from 5 to 20 nm, and the thickness of the Pt layer ranges from 300 to 1000 nm; and / or the copper-clad laminate of the PCB is replaced with a ceramic substrate or a metal substrate.

Images