High-voltage power device mixed insulating material, preparation method and application

Abstract

The invention relates to the field of power semiconductor packaging materials, in particular to a high-voltage power device mixed insulating material, a preparation method and application, and the preparation method comprises the following steps: step 1, dissolving BN nanoparticles under ultrasonic treatment by taking N, N-dimethylacetamide as a solvent to obtain a mixed solvent; step 2, adding 4, 4 '-diaminodiphenyl ether into the mixed solvent in an ice-water bath under a nitrogen atmosphere; step 3, adding 3, 3 ', 4, 4'-biphenyltetracarboxylic dianhydride into the intermediate mixture, and stirring to obtain PAA / BN; and 4, carrying out vacuum heat treatment on the PAA / BN to obtain the PI / BN insulating material. According to the invention, PI synthesized by two materials of BPDA (3, 3 ', 4, 4'-biphenyl tetracarboxylic dianhydride) and ODA (4, 4 '-diaminodiphenyl ether) through a two-step method is used as an insulating material, c-BN / h-BN is added as a nano filler by using the PI as a substrate, so that the novel insulating material is obtained, DBC of the PI / c-BN insulating material with the filler content of 10% successfully passes 7kV and 10kV partial discharge tests, no partial discharge occurs, and the insulating material has good insulation performance. And the voltage withstanding grade of the power module insulating material is improved.

Description

Technical Field

[0001] This invention relates to the field of power semiconductor packaging materials, specifically to a hybrid insulating material for high-voltage power devices, its preparation method, and its application. Background Technology

[0002] Traditional high-voltage power device insulation packaging materials are typically pure polyimide (PI). Polyimide has been widely used in high-voltage power devices due to its excellent dielectric properties and high-temperature resistance. However, with the continuous increase in the operating voltage of high-voltage power devices, the limited electrical properties of this material present a series of challenges. The dielectric mismatch between its relative permittivity and the adjacent silicon gel material leads to electric field distortion at the triple junction, with local field strengths far exceeding the silicon gel breakdown threshold, causing partial discharge during module operation. Furthermore, the low thermal conductivity of pure PI limits the module's heat dissipation capacity, and it easily leads to space charge accumulation at high temperatures, accelerating insulation aging. These problems severely restrict the performance release of wide-bandgap semiconductor devices in high-voltage, high-power-density scenarios.

[0003] With the rapid development of semiconductor technology, the voltage levels of high-voltage power devices are constantly increasing, and the performance requirements for the insulating packaging materials of high-voltage power devices are also constantly rising. Furthermore, in recent years, breakthroughs in the modification technology of polyimide nanofillers have provided a new path for its performance enhancement; electric field modulation can be achieved through compositing with the polyimide matrix. For example, CN115109285B discloses a wear-resistant polyimide insulating film and its preparation method. By introducing molybdenum disulfide nanosheets, nano-alumina, and nanocellulose prepared by the TEMPO oxidation method into the polyimide film, a three-dimensional network structure is formed, solving the problems of insufficient mechanical properties and wear resistance of the polyimide film, and improving its insulation performance and service life.

[0004] However, the selection of nanofillers and the performance of composite materials still need to be tested, and the performance of applying new insulating materials to modules also needs to be verified. Summary of the Invention

[0005] To address the issue that the insulating packaging materials of high-voltage power devices in the prior art cannot meet their performance requirements under high voltage and high power density scenarios, this invention provides a hybrid insulating material for high-voltage power devices, a preparation method, and its application.

[0006] This invention is achieved through the following technical solution: A method for preparing a hybrid insulating material for high-voltage power devices includes the following steps: Step 1: Using N,N-dimethylacetamide as a solvent, BN nanoparticles are dissolved under ultrasonic treatment to obtain a mixed solvent; Step 2: Under an ice-water bath and nitrogen atmosphere, 4,4'-diaminodiphenyl ether is added to the mixed solvent and stirred to obtain an intermediate mixture; Step 3: Add 3,3',4,4'-biphenyltetracarboxylic dianhydride to the intermediate mixture and stir to obtain PAA / BN; Step 4: Perform vacuum heat treatment on PAA / BN to obtain PI / BN insulating material.

[0007] Preferably, the molar ratio of 3,3',4,4'-biphenyltetracarboxylic dianhydride and 4,4'-diaminodiphenyl ether is 1:1.

[0008] Preferably, in step 1, BN nanoparticles account for 15% of the total solid content, and the BN nanoparticles include c-BN nanoparticles or h-BN nanoparticles.

[0009] Preferably, in step 1, the ultrasonic treatment is performed with a power of 50-100W for 1-2 hours.

[0010] Preferably, in step 1 and step 2, the temperature during the ice-water bath is 0~5℃.

[0011] Preferably, in step 3, 3,3',4,4'-biphenyltetracarboxylic dianhydride is added to the intermediate mixture in three portions over 30 minutes.

[0012] Preferably, in step 3, the stirring speed is 700~1000 r / min and the stirring time is 6~8 h.

[0013] Preferably, in step 4, during vacuum heat treatment, the vacuum degree is 0.09~0.1Pa, and a four-stage heating + holding heat treatment system is adopted.

[0014] A hybrid insulating material obtained according to the method for preparing hybrid insulating materials for high-voltage power devices.

[0015] Application of a hybrid insulating material in high-voltage power devices.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a method for preparing a hybrid insulating material for high-voltage power devices. It employs a two-step synthesis of PI (polyimide) using BPDA (3,3',4,4'-biphenyltetracarboxylic dianhydride) and ODA (4,4'-diaminodiphenyl ether) as the insulating material. c-BN / h-BN is then added as nanofillers to this base, resulting in a novel insulating material. Specifically, N,N-dimethylacetamide is used as a solvent, and BN nanoparticles are uniformly dissolved using ultrasonic-assisted dispersion to form a homogeneous mixed system. Then, 4,4'-diaminodiphenyl ether is uniformly dispersed in the solvent under ice-water bath and nitrogen protection to facilitate more complete subsequent reactions. Following this, a dianhydride-diamine condensation reaction occurs through stirring polymerization. Finally, the solvent is removed by vacuum heat treatment, promoting complete dehydration and cyclization of the amyl acid groups, forming a high-temperature resistant, high-insulation PI / BN composite material with a stable five-membered imide ring.

[0017] Furthermore, limiting the ultrasonic parameters can enhance the suppression of particle aggregation and ensure the uniform dispersion of BN in the solvent.

[0018] Furthermore, during vacuum heat treatment, the vacuum environment can promote the complete removal of the solvent, and the gradual increase in temperature can promote the complete conversion of the amide acid groups into five-membered imide rings, forming a high-temperature resistant and highly insulating PI / BN composite material. Attached Figure Description

[0019] Figure 1 This is a flowchart of a method for preparing a hybrid insulating material for high-voltage power devices according to the present invention; Figure 2 This is the heat treatment regime during vacuum heat treatment in the method for preparing hybrid insulating materials for high-voltage power devices according to the present invention; Figure 3 The dielectric constant of the mixed insulating materials with different mass fractions of c-BN in the embodiments changes at a frequency of 100Hz; Figure 4 The dielectric constant of the mixed insulating materials with different mass fractions of h-BN in the embodiments changes at a frequency of 100Hz; Figure 5 This is a dielectric loss diagram of the mixed insulating materials with different mass fractions of c-BN in the embodiments; Figure 6 This is a dielectric loss diagram of the mixed insulating materials with different mass fractions of h-BN in the embodiments; Figure 7 This is a breakdown strength diagram of the hybrid insulating material obtained in the embodiment; Figure 8 This is an electron microscope image of PI / 10c-BN in the embodiment. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0021] This invention discloses a method for preparing hybrid insulating materials for high-voltage power devices, referring to... Figure 1 This includes the following steps: Step 1: Using N,N-dimethylacetamide as a solvent, BN nanoparticles are dissolved under ultrasonic treatment to obtain a mixed solvent.

[0022] Among them, BN nanoparticles account for 15% of the total solid content, and the total solid content is the sum of the mass of BPDA solid, ODA solid and BN solid.

[0023] BN nanoparticles include c-BN nanoparticles or h-BN nanoparticles. Both of these materials are high-temperature and high-resistivity nanofillers. The addition of PI can improve thermal and insulation properties. The addition of c-BN can significantly improve the strength of the material, while the introduction of h-BN can optimize grain orientation and reduce internal defects in the material.

[0024] During ultrasonic treatment, the power is 50~100W and the time is 1~2h.

[0025] Step 2: Under an ice-water bath (0~5℃) and a nitrogen atmosphere (flowing nitrogen through a three-necked flask, one end inlet and one end outlet), 4,4'-diaminodiphenyl ether is added to the mixed solvent and stirred to obtain an intermediate mixture; Step 3: Add 3,3',4,4'-biphenyltetracarboxylic dianhydride to the intermediate mixture and stir to obtain PAA / BN.

[0026] The molar ratio of 3,3',4,4'-biphenyltetracarboxylic dianhydride to 4,4'-diaminodiphenyl ether is 1:1.

[0027] 3,3',4,4'-Biphenyltetracarboxylic dianhydride was added to the intermediate mixture in three portions over 30 minutes.

[0028] During stirring, the speed is 700~1000 r / min and the time is 6~8 h.

[0029] Step 4: Perform vacuum heat treatment on PAA / BN to obtain PI / BN insulating material.

[0030] During vacuum heat treatment, the vacuum level is 0.09~0.1 Pa, and a four-stage heating + holding heat treatment regime is adopted, referring to... Figure 2 The heat treatment process shown includes the following specific steps: First, the temperature is increased to the first step temperature (70℃) at a heating rate of 1.5℃ / min and held for 6 hours to remove solvent and residual moisture and prevent the formation of bubbles. Then, increase the temperature to the second step temperature (100℃) at a heating rate of 0.5℃ / min and hold for 1 hour to remove the solvent and residual moisture and avoid the formation of bubbles. The temperature was increased to the third step temperature (200℃) at a heating rate of 0.8℃ / min and held for 1 hour, which can accelerate the dehydration and cyclization of amyl acid to form a partial imide structure. Finally, the temperature was increased to the fourth step temperature (300℃) at a heating rate of 0.8℃ / min and held for 1 hour to ensure complete cyclization and eliminate residual ammonium acid groups.

[0031] The present invention also discloses a hybrid insulating material obtained according to the method for preparing hybrid insulating materials for high-voltage power devices.

[0032] Example 1 BPDA and ODA were weighed in a 1:1 molar ratio. Following a total solid content of 15%, gradients of BN nanoparticles were established, with mass fractions of 0%, 10%, 20%, 30%, and 40% of the solids, using DMAc (N,N-dimethylacetamide) as the solvent. c-BN nanoparticles were added to DMAc and ultrasonically dispersed for 2 hours to achieve uniform dispersion, serving as a novel solvent. Preparation was carried out under a nitrogen atmosphere in an ice-water bath: ODA was added to the novel solvent with continuous stirring. BPDA was added to the solvent in three portions over 30 minutes, and stirring was continued for 6 hours to obtain PAA (polyamic acid) / BN. PAA was then subjected to vacuum heat treatment for dehydration and DMAc removal to obtain PI / BN insulating material.

[0033] Example 2 The difference from Example 1 is that the c-BN nanoparticles account for 10% of the mass fraction of the solid.

[0034] Example 3 The difference from Example 1 is that the c-BN nanoparticles account for 20% of the mass fraction of the solid.

[0035] Example 4 The difference from Example 1 is that the c-BN nanoparticles account for 30% of the mass fraction of the solid.

[0036] Example 5 The difference from Example 1 is that the c-BN nanoparticles account for 40% of the mass fraction of the solid.

[0037] Example 6 The difference from Example 1 is that h-BN nanoparticles are used, and the mass fraction of h-BN nanoparticles in the solid is 0.

[0038] Example 7 The difference from Example 6 is that the h-BN nanoparticles account for 10% of the mass fraction of the solid.

[0039] Example 8 The difference from Example 6 is that the h-BN nanoparticles account for 20% of the mass fraction of the solid.

[0040] Example 9 The difference from Example 6 is that the h-BN nanoparticles account for 30% of the mass fraction of the solid.

[0041] Example 10 The difference from Example 6 is that the h-BN nanoparticles account for 40% of the mass fraction of the solid.

[0042] like Figure 3 , 4 As shown, at a frequency of 100Hz, the dielectric constant of pure PI is 3.64. The relative dielectric constant of the PI / BN composite material gradually increases with the increase of doping concentration, while the dielectric constant decreases with the increase of frequency. Among them, the dielectric constant of PI / c-BN increases more.

[0043] Electron microscopy was used to observe the PI / BN insulating material to verify the dispersion of BN in PI. Dielectric and breakdown properties of PI / BN were tested and compared with pure PI. The results are as follows: Figures 3-8 As shown.

[0044] like Figure 5 , 6 As shown, the dielectric loss of PI increases slowly in the low-frequency region and decreases rapidly in the high-frequency region. The dielectric loss of PI / BN decreases with the increase of electric field frequency, while the dielectric loss of PI / BN composite material gradually increases with the increase of doping concentration.

[0045] like Figure 7 As shown, when the filler content is 10 wt.%, the breakdown strength of the PI / h-BN composite material reaches a maximum of 199 kV / mm, which is 1.14 times that of pure PI; the breakdown strength of the PI / c-BN composite material also reaches a maximum of 234 kV / mm, which is 1.34 times that of pure PI.

[0046] like Figure 7 As shown, when the filler content is 10 wt.%, BN is uniformly dispersed in PI without agglomeration.

[0047] The present invention also discloses the application of a hybrid insulating material in high-voltage power devices.

[0048] The prepared PI / BN material was spin-coated onto the DBC using a spin coater at 800 r / min for 30 s. The DBC was then subjected to 7kV and 10kV high-voltage partial discharge tests to verify the insulation performance of the novel insulating material. The DBC with PI / c-BN insulation material containing 10% c-BN filler successfully passed the 7kV and 10kV partial discharge tests without experiencing partial discharge, thus improving the withstand voltage rating of the power module insulation material.

[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the technical solution of the present invention in any way. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can be modified and replaced in several simple ways, and these modifications and replacements are all within the scope of protection covered by the claims.

Claims

1. A method for preparing a hybrid insulating material for high-voltage power devices, characterized in that, Includes the following steps: Step 1: Using N,N-dimethylacetamide as a solvent, BN nanoparticles are dissolved under ultrasonic treatment to obtain a mixed solvent; Step 2: Under an ice-water bath and nitrogen atmosphere, 4,4'-diaminodiphenyl ether is added to the mixed solvent and stirred to obtain an intermediate mixture; Step 3: Add 3,3',4,4'-biphenyltetracarboxylic dianhydride to the intermediate mixture and stir to obtain PAA / BN; Step 4: Perform vacuum heat treatment on PAA / BN to obtain PI / BN insulating material.

2. The method for preparing hybrid insulating material for high-voltage power devices according to claim 1, characterized in that, The molar ratio of 3,3',4,4'-biphenyltetracarboxylic dianhydride to 4,4'-diaminodiphenyl ether is 1:

1.

3. The method for preparing hybrid insulating material for high-voltage power devices according to claim 2, characterized in that, In step 1, BN nanoparticles account for 15% of the total solid content, and the BN nanoparticles include c-BN nanoparticles or h-BN nanoparticles.

4. The method for preparing hybrid insulating material for high-voltage power devices according to claim 2, characterized in that, In step 1, the ultrasonic treatment is performed at a power of 50-100W for 1-2 hours.

5. The method for preparing hybrid insulating material for high-voltage power devices according to claim 1, characterized in that, In step 1 and step 2, the temperature during the ice-water bath is 0~5℃.

6. The method for preparing hybrid insulating material for high-voltage power devices according to claim 1, characterized in that, In step 3, 3,3',4,4'-biphenyltetracarboxylic dianhydride is added to the intermediate mixture in three portions over 30 minutes.

7. The method for preparing hybrid insulating material for high-voltage power devices according to claim 1, characterized in that, In step 3, the stirring speed is 700~1000 r / min and the stirring time is 6~8 h.

8. The method for preparing hybrid insulating material for high-voltage power devices according to claim 1, characterized in that, In step 4, during vacuum heat treatment, the vacuum level is 0.09~0.1Pa, and a four-stage heating + holding heat treatment system is adopted.

9. A hybrid insulating material obtained by the method for preparing hybrid insulating material for high-voltage power devices according to any one of claims 1 to 8.

10. The application of the hybrid insulating material as described in claim 9 in high-voltage power devices.

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