Rare earth modified plastic encapsulation material and optical fiber type in-situ temperature measuring power semiconductor device

Abstract

The present application belongs to the technical field of power semiconductor devices, and particularly relates to a rare earth modified plastic sealing material and an optical fiber type in-situ temperature measuring power semiconductor device. The rare earth modified plastic sealing material of the present application maintains the insulation performance and mechanical performance of the original epoxy plastic sealing material by adding a small amount of rare earth fluorescent material, and does not additionally occupy the packaging space; the fluorescent sensing layer is directly arranged on the surface of the chip, and can accurately reflect the real junction temperature of the chip during operation; in combination with the exposed optical fiber output light signal, non-contact in-situ temperature measurement without damaging the packaging structure can be realized, and there is no insulation risk under high pressure working condition. The present application does not need to change the core packaging structure of the original power semiconductor device, only increases the fluorescent sensing layer and the optical fiber pre-embedding process, and has good compatibility with the existing packaging production line, and the modification cost is low; at the same time, based on the temperature response characteristics of the rare earth fluorescent material, the temperature measuring precision is high, and there is no problem of long-term use parameter drift, which can provide accurate real-time temperature data for the operation state monitoring and reliability evaluation of the power semiconductor device, and effectively improves the safety and stability of the device operation.

Description

Technical Field

[0001] This invention belongs to the field of power semiconductor device technology, specifically relating to a rare earth modified molding compound and an optical fiber in-situ temperature measurement power semiconductor device. Background Technology

[0002] As a mainstream power semiconductor device, IGBTs are widely used in new energy vehicle main drives, photovoltaic inverters, energy storage converters, industrial drives, and other fields. The junction temperature of the device is a core factor affecting its operational reliability, lifespan, and power density. Traditional IGBT single-tube packages only have insulation protection and heat dissipation functions, and cannot achieve real-time, non-contact monitoring of the internal chip interface temperature without damaging the package.

[0003] Existing temperature measurement technologies have the following drawbacks: Infrared thermometry can only detect the surface temperature of the plastic encapsulation shell, resulting in a large deviation from the actual chip temperature; opening the shell for temperature measurement can damage the packaging structure, leading to device failure; contact-based temperature measurement solutions such as thermocouples and surface-mount NTCs occupy packaging space, affecting heat dissipation performance, and pose insulation risks under high-voltage conditions; the wiring of the temperature-sensing diodes built into the chip is complex, and the parameters are prone to drift over long-term use, and they cannot reflect the overall temperature distribution on the chip surface. In addition, existing technologies (such as patent CN115683386A) also monitor the temperature of semiconductor devices using fluorescent fiber optic temperature measurement devices, but because conventional IGBT epoxy encapsulation materials contain carbon black fillers, they are completely opaque, making internal optical temperature measurement impossible, and they can only measure the outer surface temperature of the power module. Summary of the Invention

[0004] The purpose of this invention is to provide a rare earth modified molding compound and an optical fiber in-situ temperature measurement power semiconductor device. The device uses a rare earth modified molding compound with an embedded optical fiber in the lead frame as the only optical temperature measurement structure. It does not change the core packaging body of the device, has strong production line compatibility, and can achieve high-precision, high-insulation in-situ temperature measurement of the chip surface on the inner wall of the device.

[0005] The first aspect of this application provides a rare earth modified molding compound, comprising: 99.0 to 99.9 wt% epoxy molding compound and 0.1 to 1.0 wt% rare earth fluorescent material.

[0006] In one embodiment of this application, the rare earth fluorescent material has temperature response capability in the temperature range of -40 to 175°C.

[0007] In one embodiment of this application, the thermal decomposition temperature of the rare earth fluorescent material is ≥250℃.

[0008] The second aspect of this application provides a method for preparing a rare earth modified molding compound, characterized in that it includes: Prepare a hydrolysis solution by mixing the surface modifier with anhydrous ethanol; The Eu / Tb mixed powder was immersed in the hydrolysate and surface grafting modification was completed by water bath stirring. Drying to remove solvent; Ball milling to obtain rare earth fluorescent material powder; Take epoxy molding compound according to the preset weight percentage, add rare earth fluorescent material powder, and then mix, knead and granulate at high speed to obtain rare earth modified molding compound.

[0009] In one embodiment of this application, the surface modifier includes silane coupling agents, amino silicone oils, polysiloxanes, etc.

[0010] In one embodiment of this application, the method for preparing the Eu / Tb mixed powder includes: Rare earth oxides are dissolved in dilute nitric acid, heated and stirred, concentrated and washed to bring the pH of the rare earth nitrate aqueous solution close to 7. Under heating and stirring, 3,5-pyridinedicarboxylic acid and 2,2-bipyridine were dissolved in an ethanol / H2O mixed solvent to obtain a ligand solution; Rare earth nitrate solution was added to ligand solution and stirred and heated. A suitable amount of dilute NaOH solution was added dropwise to adjust the pH of the solution to be close to neutral to obtain a mixture. When the mixture is heated in a water bath, a precipitate gradually appears. The mixture containing the precipitate was transferred to a hydrothermal reactor and reacted at 100°C–180°C for 6–48 hours, followed by cooling to room temperature. The precipitate was collected by filtration and washed several times with ethanol and H2O to obtain Eu / Tb mixed powder.

[0011] In one embodiment of this application, the rare earth oxides include Eu2O3 and Tb4O7.

[0012] A third aspect of this application provides a fiber optic in-situ temperature measurement power semiconductor device, comprising: Lead frame; Several chips; the bottom surface of the chips is fixed on a lead frame; Molding compound, which wraps around the chip and lead frame; A fluorescent sensing layer is disposed between the chip and the molding compound; and An optical fiber, with its inner end extending into the fluorescent sensing layer and its outer end exposed outside the molding compound, is used to output the optical signal of the fluorescent sensing layer to the outside of the molding compound.

[0013] In one embodiment of this application, the fluorescent sensing layer uses the rare earth modified molding compound as described above.

[0014] In one embodiment of this application, the thickness of the outer surface of the fluorescent sensing layer to the outer surface of the chip is 100μm to 300μm.

[0015] In one embodiment of this application, the lead frame is provided with an optical fiber positioning groove for accommodating optical fibers.

[0016] In one embodiment of this application, the coverage area of ​​the fluorescent sensing layer is larger than the outer peripheral area of ​​the chip; The inner end of the optical fiber extends into the fluorescent sensing layer on the outer periphery of the chip. The inner end of the optical fiber is 10μm to 100μm away from the chip surface.

[0017] The beneficial effects of this invention are: The rare-earth modified molding compound of this invention maintains the insulation and mechanical properties of the original epoxy molding compound by adding a small amount of rare-earth fluorescent material, without occupying additional packaging space. The fluorescent sensing layer is directly placed on the chip surface, which can accurately reflect the actual junction temperature of the chip during operation. Combined with the exposed optical fiber output signal, it can realize non-contact in-situ temperature measurement without damaging the packaging structure, and there is no insulation risk under high voltage conditions. This invention does not require modification to the core packaging structure of the original power semiconductor device, only adding a fluorescent sensing layer and optical fiber pre-embedding process. It has good compatibility with existing packaging production lines and low modification cost. At the same time, based on the temperature response characteristics of rare-earth fluorescent materials, the temperature measurement accuracy is high and there will be no problem of parameter drift over long-term use. It can provide accurate real-time temperature data for monitoring the operating status and reliability assessment of power semiconductor devices, effectively improving the safety and stability of device operation.

[0018] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained through the structures particularly pointed out in the description and the drawings.

[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of a preferred embodiment of the fiber optic in-situ temperature measurement power semiconductor device of the present invention; Figure 2This is a schematic diagram of a preferred embodiment of the fiber optic in-situ temperature measurement power semiconductor device after the molding compound has been removed. Figure 3 This is a partial cross-sectional view of a preferred embodiment of the fiber optic in-situ temperature measurement power semiconductor device of the present invention; Figure 4 This is a schematic diagram illustrating the working principle of a fiber optic temperature measurement system according to a preferred embodiment of the present invention; Figure 5 Eu is a preferred embodiment of the complex of the present invention. 0.05 Tb 0.95 Temperature-dependent emission spectrum of -PDC-Bipy under 287 nm wavelength excitation; Figure 6 Eu is a preferred embodiment of the complex of the present invention. 0.05 Tb 0.95 -PDC-Bipy under 287 nm wavelength excitation in the temperature range of 160-550 K (I Tb / I Eu The fitted curve of ) Figure 7 Eu is a preferred embodiment of the complex of the present invention. 0.05 Tb 0.95 - Relationship between absolute and relative sensitivity of PDC-Bipy under 287 nm wavelength excitation and temperature.

[0022] In the picture: 1. Lead frame, 11. Fiber optic positioning groove, 2. Chip, 3. Molding material, 4. Fluorescent sensing layer, 5. Fiber optic cable. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] This application provides a rare-earth modified molding compound and its preparation method, as well as a fiber optic in-situ temperature measurement power semiconductor device, which are described in detail below. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments of this application. Furthermore, in the following embodiments, the descriptions of each embodiment have their own emphasis; parts not described in detail in a certain embodiment can be referred to in the relevant descriptions of other embodiments.

[0025] Existing conventional IGBT encapsulation materials, containing carbon black filler, are completely opaque, making internal optical temperature measurement impossible. Therefore, there is an urgent need for an IGBT packaging solution that achieves in-situ internal temperature measurement without altering existing packaging lines or compromising device insulation and reliability. This application, based on the existing packaging structure, uses a rare-earth-modified encapsulation material doped with rare-earth fluorescent materials as the fluorescence sensing layer, coupled with pre-embedded optical fibers in the lead frame as the sole optical temperature measurement structure. This approach maintains uninterrupted core packaging processes, offers strong production line compatibility, and enables high-precision, high-insulation in-situ temperature measurement of the chip surface.

[0026] In one embodiment, the rare earth modified molding compound comprises: 99.0 to 99.9 wt% epoxy molding compound and 0.1 to 1.0 wt% rare earth fluorescent material.

[0027] Optionally, the epoxy molding compound can be a conventional commercial epoxy molding compound, such as Sumitomo's EME series (e.g., EME-G700, EME-G770, EME-7300) or Henkel's Hysol series (e.g., Hysol FP4044, Hysol GR1000).

[0028] Optionally, the rare earth fluorescent material has temperature response capability in the temperature range of -40 to 175°C.

[0029] In one embodiment of this application, the rare earth fluorescent material is a surface-modified Eu. x Tb 1-x -PDC-Bipy binuclear complex; in which Eu x Tb 1-x This indicates that the complex is a rare earth co-doped complex, where Eu is europium ions, Tb is terbium ions, x is the europium doping ratio (0 < x < 1), and Tb is the terbium doping ratio. 1-x This represents the remaining proportion of terbium. By adjusting the x value, the luminescent properties of the complex can be controlled (e.g., adjusting the ratio of red to green light). PDC stands for 3,5-pyridinedicarboxylic acid (H2PDC), an organic ligand whose nitrogen and oxygen atoms have strong coordination ability and can coordinate with rare earth ions, playing the role of "antenna effect" to efficiently transfer the absorbed light energy to rare earth ions, thereby enhancing the luminescence intensity of the complex. Bipy stands for 2,2-bipyridine (H2Bipy), which is also an organic ligand containing two nitrogen atoms. It is often used as an auxiliary ligand to coordinate with rare earth ions to stabilize the spatial structure of the complex and to participate in regulating the photophysical properties of the complex.

[0030] In this embodiment, preferably, the rare-earth fluorescent material has a thermal decomposition temperature ≥250℃. It can exhibit stable fluorescence temperature response characteristics within the range of -40℃ to 175℃.

[0031] In one embodiment, the rare earth modified molding compound can be prepared by the following method: Prepare a hydrolysis solution by mixing the surface modifier with anhydrous ethanol; The Eu / Tb mixed powder was immersed in the hydrolysate and surface grafting modification was completed by water bath stirring. Drying to remove solvent; Ball milling to obtain rare earth fluorescent material powder; Take epoxy molding compound according to the preset weight percentage, add rare earth fluorescent material powder, and then mix, knead and granulate at high speed to obtain rare earth modified molding compound.

[0032] In one embodiment, the surface modifier includes silane coupling agents, amino silicone oils, polysiloxanes, etc.

[0033] Optionally, the method for preparing the Eu / Tb mixed powder includes: Rare earth oxides are dissolved in dilute nitric acid, heated and stirred, concentrated and washed to bring the pH of the rare earth nitrate aqueous solution close to 7. Under heating and stirring, 3,5-pyridinedicarboxylic acid and 2,2-bipyridine were dissolved in an ethanol / H2O mixed solvent to obtain a ligand solution; Rare earth nitrate solution was added to ligand solution and stirred and heated. A suitable amount of dilute NaOH solution was added dropwise to adjust the pH of the solution to be close to neutral to obtain a mixture. When the mixture is heated in a water bath, a precipitate gradually appears. The mixture containing the precipitate was transferred to a hydrothermal reactor and reacted at 100°C–180°C for 6–48 hours, followed by cooling to room temperature. The precipitate was collected by filtration and washed several times with ethanol and H2O to obtain Eu / Tb mixed powder.

[0034] In one embodiment of this application, the rare earth oxides include Eu2O3 and Tb4O7.

[0035] Example 1: Preparation of Rare Earth Modified Molding Compound (1) Preparation of Eu 0.05 Tb 0.95 The material method for -PDC-Bipy binuclear complexes is as follows; Rare earth oxides Eu2O3 and Tb4O7 were prepared in a mass percentage ratio of 0.05:0.95 (Eu:Tb), dissolved in dilute nitric acid, heated and stirred, and continuously concentrated and washed to make the pH of the rare earth nitrate aqueous solution close to 7. Under heating and stirring, 3,5-pyridinedicarboxylic acid and 2,2-bipyridine were dissolved in an ethanol / H2O (4:1.V / V) mixed solvent to obtain a ligand solution; Rare earth nitrate solution was added to ligand solution and stirred and heated. A suitable amount of dilute NaOH solution was added dropwise to adjust the pH of the solution to be close to neutral to obtain a mixture. The mixture was heated in a water bath at 70°C for 1 hour, and precipitate gradually appeared. The mixture containing the precipitate was transferred to a 50 mL PTFE-lined hydrothermal reactor and reacted at 140 °C for 24 hours. Subsequently, the hydrothermal reactor was slowly cooled to room temperature (5℃ / min), the precipitate was collected by filtration, and washed several times with ethanol and H2O to obtain Eu / Tb mixed powder.

[0036] (2) Rare earth powder surface modification process A hydrolysis solution was prepared by mixing KH-560 silane coupling agent with anhydrous ethanol at a ratio of 1:9, and the hydrolysis and activation were completed by magnetic stirring at room temperature for 30 minutes. The Eu / Tb mixed powder was immersed in the hydrolysate and stirred in a water bath at 60°C for 2 hours to complete the surface grafting modification. Then it was placed in an 80℃ oven and dried for 12 hours to completely remove the solvent; Finally, a planetary ball mill was used to ball mill the rare earth fluorescent material powder at 300 r / min for 30 min to obtain a powder with uniform particle size, no agglomeration, and excellent epoxy compatibility. This step can effectively improve the dispersibility of the rare earth fluorescent material powder in the epoxy matrix and avoid problems such as high-temperature curing precipitation, agglomeration, and accelerated fluorescence quenching.

[0037] (3) Preparation process of rare earth modified molding compound Weigh 99 parts of epoxy molding compound and 1 part of rare earth fluorescent material powder according to the weight ratio. First, premix and ultrasonically disperse the powder with a portion (e.g., 10 parts) of epoxy molding compound for 15 minutes. Then add the remaining epoxy molding compound and stir at high speed for 20 minutes. Vacuum degassing is performed for 10 minutes to obtain a uniform, bubble-free, and highly dispersed rare earth modified molding compound solution for coating.

[0038] See Figures 1 to 3 In one embodiment, the fiber optic in-situ temperature measurement power semiconductor device includes: a lead frame 1; a plurality of chips 2; the bottom surface of the chips 2 is fixed on the lead frame 1; a molding compound 3 is wrapped around the outer periphery of the chips 2 and the lead frame 1; a fluorescence sensing layer 4 is disposed between the chips 2 and the molding compound 3; and an optical fiber 5, the inner end of which extends into the fluorescence sensing layer 4 and the outer end of which is exposed outside the molding compound 3, for outputting the optical signal of the fluorescence sensing layer 4 to the outside of the molding compound 3.

[0039] In this embodiment, the fluorescent sensing layer 4 can be made of rare earth modified molding compound as described above. After curing, it can be directly bonded to the surface of chip 2 to form a temperature sensing layer. It will not change the original heat dissipation path of the chip, nor will it increase the encapsulation thickness. It can accurately and in real time reflect the surface temperature changes during the chip's operation.

[0040] Optionally, the thickness of the fluorescent sensing layer 4 is 100μm to 300μm.

[0041] In some embodiments, the lead frame 1 is provided with an optical fiber positioning groove 11 for accommodating the optical fiber 5. The optical fiber 5 can be a multimode silica optical fiber with a temperature resistance of ≥200℃. During installation, the optical fiber 5 can be fixed in the optical fiber positioning groove 11 with high-temperature resistant epoxy adhesive to complete the pre-curing.

[0042] In this embodiment, the optical fiber 5 is fixed in the optical fiber positioning groove 11 of the lead frame 1 by pre-embedding. The depth of the optical fiber positioning groove 11 can match the outer diameter of the optical fiber 5, which can keep the position of the optical fiber stable during the packaging process, avoid the optical fiber from shifting away from the sensing area during the plastic sealing process, and ensure the stability of optical signal transmission.

[0043] In this embodiment, the outer end of the optical fiber exposed outside the molding compound 3 can be directly connected to an external fluorescence temperature measurement device. After the excitation light is transmitted through the optical fiber into the fluorescence sensing layer 4, it will excite the rare earth fluorescent material therein to produce characteristic fluorescence. The ratio of fluorescence intensity to temperature can be converted into a real-time temperature value through a pre-calibrated fitting curve, thereby realizing in-situ temperature measurement.

[0044] Optionally, the coverage area of ​​the fluorescence sensing layer 4 is larger than the outer peripheral area of ​​the chip 2; the inner end of the optical fiber 5 extends into the fluorescence sensing layer 4 on the outer periphery of the chip 2; the inner end of the optical fiber 5 is 10μm to 100μm away from the surface of the chip 2.

[0045] Example 2: Packaging process of fiber optic in-situ temperature measurement IGBT single-tube device (1) Pre-treatment and pre-assembly of optical fiber in TO-247-3L lead frame A commercially available TO-247-3L copper-plated silver power lead frame is selected. A long, narrow fiber positioning groove is precisely machined in the chip carrier area, with groove dimensions of 7.5mm length, 0.15mm width, and 0.08mm depth. A multimode silica fiber with an outer diameter of 125μm, a core diameter of 50μm, a numerical aperture of 0.22μm, and a temperature resistance of 200℃ is selected, and a single-fiber deployment structure is adopted.

[0046] High-temperature resistant epoxy adhesive is evenly filled into the groove. The optical fiber is then positioned and aligned with the bonding slot, with the fiber tip aligned with the active area at the center of the chip. A 100μm vertical gap is reserved between the inner end face of the fiber and the chip surface to avoid damaging the chip and bonding area during bonding. The outer end of the fiber is led out straight along the ear of the frame, with a 15mm pigtail reserved for subsequent optical path connection. The pre-assembled frame is placed in a 120℃ oven for 30 minutes to pre-fix the optical fiber structure, ensuring no displacement or fiber drift during the injection molding process.

[0047] (2) Chip mounting and bonding process Commercial 1200V automotive-grade IGBT chips are used, and they are soldered onto the lead frame using high-temperature solder paste to complete the chip mounting. The soldering temperature is 260℃ to ensure a low void ratio. 15mil ultra-high purity aluminum bonding wires are used to complete the gate and emitter double-wire bonding, and the bonding pull force and shear force meet automotive-grade packaging standards.

[0048] (3) Precise coating and pre-curing of ultrathin fluorescent sensing layer on chip surface The rare-earth modified molding compound prepared in Example 1 was uniformly coated onto the entire active area surface of the IGBT chip using precision dispensing equipment. By precisely controlling the dispensing pressure, speed, and amount of compound, a uniform fluorescent sensing film layer with a thickness of 150 μm was formed after curing, completely covering the active temperature sensing area of ​​the chip. After coating, the film was placed in a 150℃ low-temperature pre-curing oven for 15 minutes to allow the sensing layer to initially set and surface dry, preventing film damage and displacement caused by subsequent injection molding.

[0049] (4) Integral molding and high-temperature curing The pre-formed frame-chip-fiber assembly was placed into a standard TO-247 molding die and integrally injection molded using flame-retardant epoxy molding compound. The injection temperature was 175℃, the injection pressure was 70 bar, and the holding time was 90 seconds. Subsequently, it was cured at 175℃ for 2 hours to allow the epoxy resin to fully cross-link and cure. After molding, the overall molding thickness of the device was 2.0 mm, and the minimum thickness of the fiber optic sheath was 0.6 mm, meeting the requirements for high-voltage insulation and mechanical strength.

[0050] (5) Post-processing After curing, the fiber optic cables are cut, shaped, burrs are removed, and the tail fibers are cleaned up, retaining a uniform 15mm external tail fiber to complete the fabrication of a high-precision fiber optic temperature sensing IGBT device.

[0051] Device temperature measurement performance testing methods: (1) Test platform setup See Figure 4The testing system includes: a 287 nm ultraviolet stable excitation source, a dual-channel fiber optic spectrometer, a high-precision programmable high and low temperature humidity test chamber, a regulated DC power supply, and a real-time data acquisition host computer. The devices are placed inside the chamber, with fiber optic pigtails leading out to connect to an external optical system, enabling in-situ, interference-free temperature measurement and acquisition under sealed conditions.

[0052] (2) Temperature calibration and testing methods The temperature range of the incubator was set to -75℃ to 240℃, with each 40℃ temperature node serving as a test temperature point. Each temperature point was held constant for 30 minutes to ensure thermal equilibrium between the chip and the packaging system. Tb data were simultaneously collected at each temperature point. 3+ The intensity of the 543 nm green light characteristic peak and Eu 3+ Intensity of the 615 nm red light characteristic peak. For example... Figure 5 As shown, the two different luminescent centers exhibit different responses to temperature changes. Therefore, the thermometric principle of fluorescence intensity ratio can be used, i.e., using 5D₄→₇F(₅Tb₄)₂. 3+ : 543 nm) and 5D0→7F (2 Eu) 3+ The transition intensity ratio (I: 615 nm) Tb / I Eu To achieve temperature measurement with self-calibration function, a temperature-fluorescence ratio calibration model is constructed. Compared with single-intensity temperature measurement, ratio temperature measurement can effectively offset systematic errors such as light source power fluctuation, fiber coupling loss, and micro-dust interference, and greatly improve the stability and repeatability of temperature measurement.

[0053] (3) Static temperature range temperature measurement linearity performance like Figure 6 As shown, within the full operating temperature range of -75 to 240℃, the rare earth complex exhibits a dual fluorescence peak intensity ratio I. Tb / I Eu It exhibits a good exponential relationship with temperature T, which can be expressed by formula (1): (1) Where A=1.13, B=24.66, and the correlation coefficient R is the linear correlation coefficient. 2 =0.991, indicating that within this temperature range, Eu 0.05 Tb 0.95 -PDC-Bipy fluorescence intensity ratio (I Tb / I Eu The temperature exhibits a good linear relationship with the temperature. To evaluate the temperature measurement performance of this sample, the absolute and relative sensitivities (Sa, Sr) are obtained using the following formulas (2) and (3): (2) (3) like Figure 7 Eu 0.05 Tb 0.95 The absolute sensitivity of the PDC-Bipy is at its maximum value Sa = 0.79%K. -1 Furthermore, under actual operating conditions of approximately 125℃, the maximum temperature sensing sensitivity is 0.32% / K (Sr = 0.32%K). -1 The maximum temperature measurement error across the entire temperature range is ≤1.25℃, and the temperature measurement accuracy is far superior to traditional infrared temperature measurement solutions for outer shells.

[0054] In summary, the rare-earth modified molding compound and fiber-optic in-situ temperature measurement power semiconductor device provided by this invention, by adding an ultra-thin sensing layer doped with rare-earth fluorescent material between the chip and the conventional molding compound, and using a pre-embedded optical fiber to achieve optical signal transmission, not only retains the insulation performance and mechanical reliability of the original packaging structure, but also achieves high-precision in-situ temperature measurement on the chip surface, solving the industry pain point that existing packaging technologies cannot directly obtain the actual junction temperature of power semiconductor chips.

[0055] The invention involves minimal process modifications, exhibits good compatibility with existing power semiconductor packaging production lines, and has low modification costs. The resulting temperature sensing device demonstrates excellent long-term stability and eliminates parameter drift issues. It can meet the operational status monitoring requirements of power semiconductor devices in high-voltage and high-reliability application scenarios such as automotive and industrial applications, providing accurate real-time temperature data support for device reliability assessment and lifespan prediction.

[0056] It should be noted that all the devices (parts whose specific structures are not specified) selected in this application are general standard parts or parts known to those skilled in the art, and their structures and principles can be known to those skilled in the art through technical manuals or conventional experimental methods.

[0057] In the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances.

[0058] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0059] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A rare earth modified molding compound, characterized in that, include: 99.0–99.9 wt% epoxy molding compound and 0.1–1.0 wt% rare earth fluorescent material.

2. The power semiconductor device according to claim 1, characterized in that, The rare earth fluorescent material has temperature response capability in the temperature range of -40 to 175℃.

3. The power semiconductor device according to claim 1, characterized in that, The rare earth fluorescent material has a thermal decomposition temperature ≥250℃.

4. A method for preparing the rare earth modified molding compound as described in claim 1, characterized in that, include: Prepare a hydrolysis solution by mixing the surface modifier with anhydrous ethanol; The Eu / Tb mixed powder was immersed in the hydrolysate and surface grafting modification was completed by water bath stirring. Drying to remove solvent; Ball milling to obtain rare earth fluorescent material powder; Take epoxy molding compound according to the preset weight percentage, add rare earth fluorescent material powder, and then mix, knead and granulate at high speed to obtain rare earth modified molding compound.

5. The method for preparing rare earth modified molding compound according to claim 4, characterized in that, The method for preparing the Eu / Tb mixed powder includes: Rare earth oxides are dissolved in dilute nitric acid, heated and stirred, concentrated and washed to bring the pH of the rare earth nitrate aqueous solution close to 7. Under heating and stirring, 3,5-pyridinedicarboxylic acid and 2,2-bipyridine were dissolved in an ethanol / H2O mixed solvent to obtain a ligand solution; Rare earth nitrate solution was added to ligand solution and stirred and heated. A suitable amount of dilute NaOH solution was added dropwise to adjust the pH of the solution to be close to neutral to obtain a mixture. When the mixture is heated in a water bath, a precipitate gradually appears. The mixture containing the precipitate was transferred to a hydrothermal reactor and reacted at 100°C–180°C for 6–48 hours, followed by cooling to room temperature. The precipitate was collected by filtration and washed several times with ethanol and H2O to obtain Eu / Tb mixed powder.

6. A fiber optic in-situ temperature measurement power semiconductor device, characterized in that, include: Lead frame (1); Several chips (2); the bottom surface of the chips (2) is fixed on the lead frame (1); Molding compound (3) is wrapped around the outer periphery of the chip (2) and the lead frame (1); A fluorescent sensing layer (4) is disposed between the chip (2) and the molding compound (3); as well as An optical fiber (5) extends into the fluorescent sensing layer (4) at its inner end and is exposed outside the molding compound (3) at its outer end, and is used to output the optical signal of the fluorescent sensing layer (4) to the outside of the molding compound (3).

7. The power semiconductor device according to claim 1, characterized in that, The fluorescent sensing layer (4) is made of the rare earth modified molding compound as described in claim 1.

8. The power semiconductor device according to claim 1, characterized in that, The thickness of the outer surface of the fluorescent sensing layer (4) to the outer surface of the chip (2) is 100μm to 300μm.

9. The power semiconductor device according to claim 1, characterized in that, The lead frame (1) is provided with an optical fiber positioning groove (11) for accommodating optical fibers (5).

10. The power semiconductor device according to claim 1, characterized in that, The coverage area of ​​the fluorescent sensing layer (4) is larger than the outer peripheral area of ​​the chip (2); The inner end of the optical fiber (5) extends into the fluorescent sensing layer (4) on the outer periphery of the chip (2); The inner end of the optical fiber (5) is 10μm to 100μm away from the surface of the chip (2).

Images