Self-repairing insulating material for power module packaging and preparation method of self-repairing insulating material

Abstract

The invention discloses a self-repairing insulating material for power module packaging and a preparation method of the self-repairing insulating material. The self-repairing insulating material comprises an epoxy prepolymer and a dynamic curing agent, wherein the dynamic curing agent is a reaction product prepared by taking a fluorine-containing diamine compound and a dialdehyde compound as reaction raw materials. According to the self-repairing insulating material disclosed by the invention, a rigid covalent cross-linked network containing dynamic imine bonds and trifluoromethyl is introduced into a polymer molecular chain, so that the self-repairing insulating material has the functions of repairing electrical tree branches, mechanical cracking and other damages while giving consideration to the electrical insulating property and the thermal mechanical property; therefore, the operation reliability and safety of the packaging module are enhanced; and the performance of the self-repairing insulating material is adjustable, so that the actual application requirements of different working conditions can be met.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of electrical materials, and in particular, relates to a self-repairing insulating material for power module packaging and a preparation method thereof. BACKGROUND

[0002] In a wire-bonding type power module, a thermosetting polymer represented by epoxy resin and silicone gel is often used as a packaging material to protect the internal chips and wires from environmental pollution, to enhance the electrical insulation between conductive electrodes, and to provide necessary mechanical support under certain conditions, which has an important influence on the voltage resistance and operating life of the power module.

[0003] However, with the development trend of power module compactness and miniaturization, the packaging material will bear higher thermal mechanical stress and electrical stress, thus being more prone to damage. Among them, the junction of the copper metal layer, the ceramic substrate and the polymer packaging material often has obvious electric field distortion due to material dielectric inhomogeneity and sharp geometric structure, which easily causes partial discharge in the packaging material and further induces electrical treeing damage. Moreover, the power module is mainly controlled by pulse width modulation, and the packaging material is subjected to high-frequency square wave modulation voltage for a long time, and the rising and falling edges are extremely steep, thus greatly increasing the probability of electrical treeing aging damage in the packaging material. In addition, when the overall power module undergoes cold-hot temperature cycling, due to the mismatch of the thermal expansion coefficients of the packaging material and the chips or ceramic substrate, there is a large thermal mechanical stress at the contact interface of the two, which will cause brittle cracking of the packaging material when it exceeds the stress bearing strength of the packaging material, and easily form stress concentration points. These two common damages are shown in FIG. 1. Under the actual operating conditions of the power module, the multi-field coupling factors such as electric field, temperature field and mechanical force field jointly act, and these defects also become weak points prone to partial discharge, promoting the electrical treeing aging process, and continuously expanding and gradually evolving into a packaging failure problem on a macro scale, threatening the safe operation of the power system and electrical equipment. Figure 2

[0004] At present, there are mainly two research routes for the problem that the power module packaging material is prone to damage: one is to improve the electrical strength and mechanical strength of the polymer packaging material by doping functional inorganic particles or modifying molecular chains to resist higher electrical stress and thermal mechanical stress, but once the material is damaged, it will still completely fail due to the continuous accumulation of irreversible damage, resulting in the power module being unable to continue to be put into use; the other is to actively endow the polymer packaging material with self-repairing performance, which can repair the damage produced under actual operating conditions in time, greatly prolong the service time of the power module, and reduce the waste of resources, showing good application prospects.

[0005] ​For self-repairing insulation materials, there are currently mainly three types: targeted magnetic heat repair system, microcapsule type and intrinsic type. For the targeted magnetic heat repair system, a thermoplastic matrix is needed to achieve local remelting and repair under the magnetic heat effect, which is obviously not suitable for commonly used thermosetting encapsulation materials such as epoxy resin and silicone gel. Moreover, high-frequency and high-intensity oscillating magnetic field is needed to trigger the repair, which may cause additional interference to the normal operation of the power module. For the microcapsule type self-repairing system, when the concentration of microcapsules exceeds a certain limit, the electric field inside the material will be significantly distorted, and the tensile strength, electric breakdown strength and other properties of the material will be severely deteriorated, and damage is more likely to occur. For the intrinsic self-repairing system, reversible covalent bonds are introduced into the chain or reversible interactions are introduced between the chains by modifying the molecular chain, and the repair of damage is realized through chain segment diffusion, rearrangement and randomization. However, the electrical, mechanical, thermal properties, repair conditions and repair effects of different systems are different, and their adaptability in power module encapsulation still needs to be further verified.

[0006] The existing patent CN114805793A discloses a self-repairing silicone elastomer based on rare earth coordination, but the realization of its self-repairing function needs to introduce rare earth metal salt, and a large number of metal ions in the matrix will significantly reduce the volume resistivity and breakdown strength of the material, increase the dielectric loss, and are not suitable for power module encapsulation materials. Patent CN114230749A discloses a self-repairing epoxy resin cured product based on dynamic hindered urea bond, but in order to achieve ideal repair effect, not only heating treatment is needed, but also high pressure up to 5-10 MPa is needed, and the hot-pressing condition is obviously difficult to realize in the power module.

[0007] Therefore, the present application is proposed. SUMMARY

[0008] The present application is based on the discovery and understanding of the inventors on the following facts and problems: Considering that power module encapsulation materials are mainly epoxy resin and silicone gel, and epoxy resin has the advantages of high adhesion, high hardness / compressive strength, excellent insulation performance and easy processability, the present application modifies and designs the material based on the epoxy resin as the basic molecular chain skeleton.

[0009] The present application aims to at least partially solve one of the technical problems in the related art.

[0010] To this end, the embodiments of the present application propose, on one hand, a self-repairing insulation material for power module encapsulation.

[0011] On the other hand, the embodiments of the present application also propose a preparation method of the self-repairing insulation material for power module encapsulation.

[0012] The self-repairing insulating material for power module packaging of the embodiment of the present application comprises an epoxy prepolymer and a dynamic curing agent; wherein the dynamic curing agent is a reaction product prepared by taking a fluorine-containing diamine-based compound and a dialdehyde-based compound as reaction raw materials.

[0013] In some embodiments, the fluorine-containing diamine-based compound needs to satisfy: a. containing position-symmetrical trifluoromethyl groups in the molecular structure; b. the amine groups contained in the molecular structure being primary amines; And / or, the dialdehyde-based compound needs to satisfy: containing a benzene ring or an alicyclic structure in the molecular structure.

[0014] In some embodiments, the dialdehyde-based compound comprises at least one of p-xylylene dialdehyde, a derivative of p-xylylene dialdehyde, cyclohexane-1,4-dialdehyde, a derivative of cyclohexane-1,4-dialdehyde; And / or, the fluorine-containing diamine-based compound comprises at least one of 2,2'-bis(trifluoromethyl)diaminobiphenyl, a derivative of 2,2'-bis(trifluoromethyl)diaminobiphenyl, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, a derivative of 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane.

[0015] In some embodiments, the epoxy prepolymer comprises at least one of bisphenol A type diglycidyl ether, hydrogenated bisphenol A type diglycidyl ether, bisphenol F type diglycidyl ether.

[0016] The preparation method of the self-repairing insulating material for power module packaging of the embodiment of the present application comprises the following steps: (1) under a nitrogen protective atmosphere, separately dissolving a fluorine-containing diamine-based compound and a dialdehyde-based compound in the same first organic solvent to obtain a fluorine-containing diamine-based compound solution and a dialdehyde-based compound solution; (2) under a nitrogen protective atmosphere, adding the dialdehyde-based compound solution dropwise into the stirring fluorine-containing diamine-based compound solution, continuing to stir after the dropwise addition is completed, then heating and performing a heat preservation reaction; (3) pouring the reaction liquid obtained in the step (2) into a precipitation solvent to precipitate, and then washing, suction-filtering, vacuum-drying, grinding and sieving the precipitate to obtain a dynamic curing agent; (4) mixing the dynamic curing agent with an epoxy prepolymer, adding a second organic solvent into the obtained mixture, preheating and stirring until the curing agent is completely dissolved in the mixture system to obtain a clear mixture; (5) pouring the clear mixture into a mold to perform vacuum degassing, then heating to perform a first curing, and then continuing to heat to perform a second curing to obtain the self-repairing insulating material for power module packaging.

[0017] In some embodiments, in step (1), the molar ratio of the fluorinated diamine compound to the dialdehyde compound is (1.2~2):1, preferably (1.5~1.8):1; And / or, the first organic solvent is an anhydrous polar aprotic organic solvent, including at least one of anhydrous N,N-dimethylformamide, anhydrous N,N-dimethylacetamide, anhydrous dimethyl sulfoxide, and anhydrous N-methylpyrrolidone; And / or, the solid content of the fluorinated diamine compound solution is 30wt%~60wt%, preferably 40wt%~50wt%; And / or, the solid content of the dialdehyde compound solution is 10wt% to 40wt%, preferably 20wt% to 30wt%.

[0018] In some embodiments, in step (2), the dropping rate is 5~30 mL / min, and the stirring speed is 200~600 r / min; And / or, the temperature for continued stirring is room temperature, and the reaction time is 0.5~1h; And / or, the reaction temperature of the heat preservation reaction is 50~70℃, and the reaction time is 1~3h.

[0019] In some embodiments, in step (3), the volume ratio of the reaction solution to the precipitation solvent is 1:(5~20), preferably 1:(8~12); And / or, the precipitation solvent is deionized water; And / or, the vacuum drying temperature is 50~70℃, and the drying time is 12~36h; And / or, the sieving is through a 50-200 mesh sieve.

[0020] In some embodiments, in step (4), the molar ratio of the active amine hydrogen in the dynamic curing agent to the epoxy group in the epoxy prepolymer is (0.95~1.05):1; And / or, the second organic solvent includes at least one of anhydrous N,N-dimethylformamide and anhydrous N,N-dimethylacetamide; the amount of the second organic solvent added is 10% to 30% of the total mass of the dynamic curing agent and the epoxy prepolymer; And / or, the preheating temperature is 80~130℃, and the preheating time is 20~50min.

[0021] In some embodiments, the vacuum degassing time in step (4) is 2 to 10 minutes; And / or, the temperature of the first curing is 70~100℃, and the curing time is 8~12h; And / or, the temperature of the second curing is 130~160℃, and the curing time is 3~6h.

[0022] The advantages and beneficial effects of the embodiments of the present invention are as follows: (1) The present invention provides a novel self-healing power module packaging material. By introducing reversible imine bonds and trifluoromethyl groups with strong electronegativity into the epoxy crosslinking network, the material can not only effectively repair common damage to power module packaging materials such as electrical treeing and mechanical cracking, but also improve the thermomechanical stability and electrical insulation performance of the packaging material. From both perspectives, it is beneficial to enhance the operational reliability and safety of the packaging module and greatly reduce the risk of module failure.

[0023] (2) The performance of the self-healing insulating material for power module packaging in this embodiment of the invention is adjustable and easy to adjust. It only requires precise control of the relative proportion of the reactive monomers to adjust the molecular structure of the dynamic curing agent, thereby preparing packaging materials with different crosslinking densities, trifluoromethyl content and dynamic imine bond content to meet the actual application needs of different working conditions and has a wide range of applications.

[0024] (3) The preparation method of the self-healing insulating material for power module packaging in the present invention is simple, the synthesis conditions are easy to achieve, and the synthesis process and product properties are stable, making it easy to promote and apply in industrial applications.

[0025] (4) The repair conditions of the self-healing insulating material for power module packaging in this embodiment of the invention are easy to implement. It is only necessary to apply a high temperature (far lower than the temperature that the chip in the power module can withstand) during the regular maintenance of the power module to achieve good repair of the damaged parts.

[0026] (5) The self-healing insulating material for power module packaging in this embodiment of the invention has good degradability. It can be controlled to degrade into small molecule products through acidic solution. The products can be recycled and purified in a closed loop and reused for synthesis, reducing resource waste and production costs. Attached Figure Description

[0027] Figure 1 This is a process flow diagram of the preparation method of the self-healing insulating material for power module packaging according to an embodiment of the present invention.

[0028] Figure 2 This diagram illustrates common damage and failure modes in existing power module packaging applications. Detailed Implementation

[0029] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0030] In this document, when values ​​are described as ranges, it should be understood that such disclosure includes disclosure of all possible subranges within that range, as well as the specific numerical values ​​falling within that range, regardless of whether the specific numerical value or specific subrange is explicitly specified.

[0031] In this article, the words “contain” and “include” and their various variations mean that other elements or wholes may be included but not specifically described.

[0032] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three kinds of relationships. For example, A and / or B can represent three cases: A exists alone, A and B exist simultaneously, and B exists alone.

[0033] The self-healing insulating material for power module packaging according to embodiments of the present invention includes an epoxy prepolymer and a dynamic curing agent; wherein the dynamic curing agent is a reaction product prepared by using a fluorinated diamine compound and a dialdehyde compound as reactants.

[0034] In some embodiments, the fluorinated diamine compound needs to satisfy the following: a. The molecular structure contains a positionally symmetrical trifluoromethyl group, which acts as a trap inside the material to capture and bind free charges in a timely manner, suppress the electron avalanche breakdown process, and improve the electrical insulation performance of the material; b. The amine group contained in the molecular structure is a primary amine, part of which can react with the aldehyde group to form a reversible Schiff bond (a special form of imine bond), and the other part can undergo a nucleophilic addition reaction with the epoxy prepolymer to form a nonlinear cross-linked network structure; And / or, the dialdehyde compound needs to satisfy the following: the molecular structure contains a benzene ring or alicyclic structure to improve the thermo-mechanical properties of the curing agent and the entire epoxy resin crosslinking network; and the aldehyde group in the dialdehyde compound has high activity and is easy to undergo condensation reaction with the amine group.

[0035] Optionally, the dialdehyde compound includes at least one of terephthalaldehyde, terephthalaldehyde derivatives, cyclohexane-1,4-dicarboxaldehyde, and cyclohexane-1,4-dicarboxaldehyde derivatives. And / or, the fluorinated diamine compound includes at least one of 2,2'-di(trifluoromethyl)diaminobiphenyl, derivatives of 2,2'-di(trifluoromethyl)diaminobiphenyl, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, and derivatives of 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane.

[0036] In some embodiments, the epoxy prepolymer is a liquid epoxy prepolymer, including at least one of bisphenol A diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, and bisphenol F diglycidyl ether.

[0037] The following is in conjunction with the appendix Figure 1 This invention describes in detail the preparation method of a self-healing insulating material for power module packaging according to embodiments of the present invention.

[0038] The method for preparing a self-healing insulating material for power module packaging according to an embodiment of the present invention includes the following steps: (1) Under a nitrogen protective atmosphere, the fluorinated diamine compound and the dialdehyde compound were dissolved separately in the same first organic solvent and stirred to dissolve, so as to obtain a solution of the fluorinated diamine compound and a solution of the dialdehyde compound. (2) Under a nitrogen protective atmosphere, the dialdehyde compound solution is added dropwise to the fluorinated diamine compound solution while it is being stirred. After the addition is complete, the reaction is stirred and then heated to maintain the temperature. (3) Pour the reaction solution obtained in step (2) into the precipitation solvent to precipitate the precipitate. The precipitate is washed, filtered, vacuum dried, ground and sieved to obtain the dynamic curing agent. (4) Mix the dynamic curing agent with the epoxy prepolymer, add a second organic solvent to the resulting mixture, preheat and stir until the curing agent is completely dissolved in the mixture system to obtain a clear mixture; (5) Pour the clarified mixture into a mold for vacuum degassing, then heat it for the first curing, and then continue to heat it for the second curing to obtain the self-healing insulating material for power module packaging.

[0039] The process design of the self-healing insulating material preparation method for power module packaging in this invention is based on introducing a rigid covalent crosslinking network containing dynamic imine bonds and trifluoromethyl groups into the polymer (such as epoxy resin) molecular chain. This allows the material to repair damage such as electrical treeing and mechanical cracking while maintaining both electrical insulation and thermo-mechanical properties. Furthermore, the crosslinking density, trifluoromethyl group content, and dynamic imine bond content of the self-healing insulating material prepared by this method can be precisely controlled through the stoichiometry of the monomers, thereby directly regulating the modulus, electrical strength, and self-healing properties of the resulting material. This preparation method is suitable for fields with extremely high requirements for reliability, lifespan, and functionality, such as power module packaging, and can extend the service life of power equipment and improve the reliability and safety of power systems.

[0040] In some embodiments, in step (1), the molar ratio of the fluorinated diamine compound to the dialdehyde compound is (1.2~2):1, preferably (1.5~1.8):1. This molar ratio determines the content of imine bonds and trifluoromethyl groups in the obtained dynamic curing agent, as well as the average relative molecular mass of the curing agent, which has a direct impact on the performance of the self-healing insulating material for power module packaging prepared subsequently. And / or, the first organic solvent is an anhydrous polar aprotic organic solvent, including at least one of anhydrous N,N-dimethylformamide, anhydrous N,N-dimethylacetamide, anhydrous dimethyl sulfoxide, and anhydrous N-methylpyrrolidone, and the selected solvents all have good compatibility with fluorinated diamine compounds and dialdehyde compounds. And / or, the solid content of the fluorinated diamine compound solution is 30wt%~60wt%, preferably 40wt%~50wt%; And / or, the solid content of the dialdehyde compound solution is 10wt% to 40wt%, preferably 20wt% to 30wt%.

[0041] If the concentration of the fluorinated diamine compound solution or the dialdehyde compound solution is too low, it will result in low curing agent synthesis efficiency and easy consumption of too much organic solvent; however, if the concentration is too high, it will not dissolve easily, resulting in the entire preparation process taking too long.

[0042] In some embodiments, in step (2), the dropping rate is 5~30 mL / min, and the stirring speed is 200~600 r / min; And / or, the temperature for continued stirring is room temperature, and the reaction time is 0.5~1h, so that the reaction starts slowly and avoids explosive polymerization due to high reactant concentration; And / or, the reaction temperature of the heat preservation reaction is 50~70℃, and the reaction time is 1~3h.

[0043] In some embodiments, in step (3), the volume ratio of the reaction solution to the precipitating solvent is 1:(5~20), preferably 1:(8~12; if the proportion of the precipitating solvent is too high, although it is beneficial to complete precipitation and washing impurities, it will waste solvent; but if the proportion of the precipitating solvent is too low, it may lead to incomplete precipitation or product agglomeration. Therefore, in the embodiments of the present invention, the proportion of the precipitating solvent is controlled within the above range. And / or, the precipitation solvent should be a good solvent for the first organic solvent and a poor solvent for the product. Therefore, the precipitation solvent in the embodiments of the present invention is preferably deionized water. And / or, the vacuum drying temperature is 50~70℃, and the drying time is 12~36h; And / or, the sieving is through a 50-200 mesh sieve.

[0044] In some embodiments, in step (4), the molar ratio of the active hydrogen amine group in the dynamic curing agent to the epoxy group in the epoxy prepolymer is (0.95~1.05):1, ensuring that it is near the standard stoichiometric ratio; And / or, the second organic solvent is an anhydrous good solvent for the dynamic curing agent and the epoxy prepolymer; further, the second organic solvent includes at least one of anhydrous N,N-dimethylformamide and anhydrous N,N-dimethylacetamide; the amount of the second organic solvent added is 10% to 30% of the total mass of the dynamic curing agent and the epoxy prepolymer; And / or, the preheating temperature is 80~130℃, and the preheating time is 20~50min.

[0045] In some embodiments, the vacuum degassing time in step (4) is 2 to 10 minutes; And / or, the temperature of the first curing is 70~100℃, and the curing time is 8~12h; And / or, the temperature of the second curing is 130~160℃, and the curing time is 3~6h.

[0046] By employing a two-stage gradient curing process, the residual amine and epoxy groups in the reaction system are made to react as completely as possible, thereby improving the degree of crosslinking and structural integrity of the system.

[0047] The self-healing insulating material of this invention is designed for power module packaging (also known as power electronic module packaging). When the self-healing insulating material used for packaging is damaged, during the periodic maintenance of the module, it only needs to be treated under high temperature conditions for a period of time. The rate of metathesis reaction of the imine bonds inside the material is accelerated, the bond exchange rate is enhanced, and the chain segment rearrangement promotes damage repair.

[0048] The following are non-limiting embodiments and comparative examples of the present invention. It should be noted that the schemes in the comparative examples are not prior art, but are only set up for comparison with the schemes in the embodiments, and are not intended to limit the present invention. Unless otherwise stated, all raw materials used in the embodiments and comparative examples are conventional commercially available products, or can be prepared by known methods.

[0049] Example 1 This embodiment provides a self-healing insulating material for power module packaging, comprising an epoxy prepolymer and a dynamic curing agent; wherein the epoxy prepolymer is bisphenol A diglycidyl ether (EPON). TMResin 828 (EP828, with a molar equivalent of 187 g / eq, meaning that 1 mole of epoxy group is contained in every 187 g of EP828); the dynamic curing agent is a reaction product prepared by reacting terephthalaldehyde and 2,2'-bis(trifluoromethyl)diaminobiphenyl as reactants.

[0050] This embodiment also provides a method for preparing the above-mentioned self-healing insulating material for power module packaging, including the following steps: (1) Under a nitrogen protective atmosphere, 16.33 g of 2,2'-bis(trifluoromethyl)diaminobiphenyl was dissolved in 20 g of anhydrous N,N-dimethylformamide, and 4.02 g of terephthalaldehyde was dissolved in 14 g of anhydrous N,N-dimethylformamide (i.e., the molar ratio of 2,2'-bis(trifluoromethyl)diaminobiphenyl to terephthalaldehyde was 1.7:1). The two solutions were stirred thoroughly separately until completely dissolved to obtain a clear 2,2'-bis(trifluoromethyl)diaminobiphenyl solution and a clear terephthalaldehyde solution. (2) Under a nitrogen protective atmosphere and at room temperature, the solution containing 2,2'-bis(trifluoromethyl)diaminobiphenyl was transferred to a three-necked flask equipped with a mechanical stirrer with a stirring rate of 300 r / min. Then, the terephthalaldehyde solution was added dropwise at a dropping rate of 5 mL / min. After the addition was completed, the reaction was stirred at room temperature for 30 min. Then, the temperature was raised to 60 °C and the reaction was kept at that temperature for 2 h. (3) Add 40 mL of the reaction solution obtained in step (2) to 400 mL of deionized water. A large amount of precipitate is precipitated. The precipitate is washed twice with deionized water, filtered, and dried in a vacuum oven at 60 °C for 24 h. Then it is ground in a mortar and pestle and passed through a 100-mesh sieve to obtain a yellow powdery dynamic curing agent. (4) Mix 12.11g of dynamic curing agent powder with 9.35g of bisphenol A type diglycidyl ether EPON TM Resin 828 (in this ratio, the molar ratio of the active hydrogen of the amino group in the dynamic curing agent to the epoxy group in the epoxy prepolymer is 1:1) is mixed, and 5.5g of anhydrous N,N-dimethylformamide is added to the resulting mixture. The mixture is preheated at 120°C and stirred for 40min until the curing agent is completely dissolved in the mixture system to obtain a clear mixture. (5) Pour the clarified mixture obtained in step (4) into a mold, degas it under vacuum for 5 minutes, and then place it in an 80°C forced-air oven to cure for 12 hours. Then continue to heat it to 150°C to cure for 4 hours to obtain a self-healing insulating material for power module packaging.

[0051] The glass transition temperature of the obtained self-healing insulation material was measured using a thermomechanical property analyzer. The self-healing insulation material was cut into strips approximately 20mm × 5mm × 0.5mm in length and width, and subjected to a tensile test at a frequency of 1Hz. The temperature range for the entire test was 0–250°C, with a heating rate of 3°C / min. The glass transition temperature of the obtained self-healing insulation material was determined by tan φ. delta The temperature corresponding to the peak value of the -T curve is determined.

[0052] The volume resistivity of the obtained self-healing insulating material was tested using a three-electrode method: The self-healing insulating material was cut into square sheets of approximately 30 mm × 30 mm × 0.5 mm. Gold electrodes with a diameter of 20 mm and a thickness of approximately 20 nm were sputtered on both sides directly opposite the center. A 1 kV DC voltage was applied to both sides of the self-healing insulating material, and the leakage current of the self-healing insulating material was recorded after the DC voltage was applied for 10 minutes, thereby obtaining the corresponding volume resistivity.

[0053] Using a clean blade, cross-shaped scratches were made on the surface of the obtained self-healing insulating material. The scratch width was between 50 and 150 μm, and the length could reach several millimeters. The size of this type of damage is larger than the initial size of damage to power module packaging materials under actual operating conditions. After the damage was formed, the obtained self-healing insulating material was placed at 220°C for 6 hours, and the change in scratch width was observed. The scratch width was recorded. d As a reference variable before and after repair, the width was measured at three random locations along the same scratch, and the average value was calculated to quantitatively determine the repair efficiency. f As shown in the following formula.

[0054]

[0055] Tests showed that the glass transition temperature of the self-healing insulating material prepared in this embodiment was 171°C, and the volume resistivity was within 10⁻⁶. 16 With a strength on the order of Ω·cm, the damage repair efficiency can reach 87%.

[0056] Example 2 This embodiment is basically the same as Example 1, except that: in this embodiment, the fluorinated diamine compound is selected as 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane when synthesizing the dynamic curing agent.

[0057] The self-healing insulating material prepared in this embodiment has a glass transition temperature of 162°C and a volume resistivity of 10⁻⁶. 16 With a strength on the order of Ω·cm, the damage repair efficiency can reach 91%.

[0058] Example 3 This embodiment is basically the same as Example 1, except that: in this embodiment, when synthesizing the dynamic curing agent, the dialdehyde compound is selected as cyclohexane-1,4-dicarboxaldehyde.

[0059] The self-healing insulating material prepared in this embodiment has a glass transition temperature of 168°C and a volume resistivity of 10⁻⁶. 16 With a strength on the order of Ω·cm, the damage repair efficiency can reach 86%.

[0060] Example 4 This embodiment is basically the same as that of Embodiment 1, except that: in this embodiment, when synthesizing the dynamic curing agent, the molar ratio of 2,2'-bis(trifluoromethyl)diaminobiphenyl to terephthalaldehyde in step (1) is 1.8:1.

[0061] The self-healing insulating material prepared in this embodiment has a glass transition temperature of 175°C and a volume resistivity of 10⁻⁶. 16 With a strength on the order of Ω·cm, the damage repair efficiency can reach 80%.

[0062] Comparative Example 1 This comparative example is basically the same as Example 1, except that the curing agent used in this comparative example is 4,4'-diaminodiphenylmethane.

[0063] The glass transition temperature of the final product obtained in this comparative example was 152°C, lower than the test value in the examples; the volume resistivity was below 10. 15 The value is on the order of Ω·cm. Furthermore, since the obtained material does not contain dynamic reversible imine bonds, it has virtually no ability to repair surface scratches, and the damage repair efficiency is less than 20%.

[0064] Comparative Example 2 This comparative example is basically the same as Example 1, except that the curing method in step (5) of this comparative example is one-time curing: curing only in a 100°C forced-air oven for 12 hours.

[0065] Due to insufficient curing, unreacted amine and epoxy groups remained inside the material in this comparative example, leading to a lower overall crosslinking density. Consequently, the glass transition temperature of the resulting product was only 128°C, and the volume resistivity was below 10⁻⁶. 15 The damage repair efficiency is on the order of Ω·cm, with a damage repair efficiency of 83%.

[0066] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0067] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A self-healing insulating material for power module packaging, characterized in that, It includes epoxy prepolymer and dynamic curing agent; wherein the dynamic curing agent is a reaction product prepared by using fluorinated diamine compounds and dialdehyde compounds as reactants.

2. The self-healing insulating material for power module packaging according to claim 1, characterized in that, The fluorinated diamine compound must satisfy the following conditions: a. It contains a positionally symmetrical trifluoromethyl group in its molecular structure; b. The amino group in its molecular structure is a primary amine. And / or, the dialdehyde compound needs to satisfy the following condition: the molecular structure contains a benzene ring or an alicyclic structure.

3. The self-healing insulating material for power module packaging according to claim 1 or 2, characterized in that, The dialdehyde compound includes at least one of terephthalaldehyde, terephthalaldehyde derivatives, cyclohexane-1,4-dicarboxaldehyde, and cyclohexane-1,4-dicarboxaldehyde derivatives. And / or, the fluorinated diamine compound includes at least one of 2,2'-di(trifluoromethyl)diaminobiphenyl, derivatives of 2,2'-di(trifluoromethyl)diaminobiphenyl, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, and derivatives of 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane.

4. The self-healing insulating material for power module packaging according to claim 1, characterized in that, The epoxy prepolymer includes at least one of bisphenol A diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, and bisphenol F diglycidyl ether.

5. A method for preparing a self-healing insulating material for power module packaging as described in any one of claims 1-4, characterized in that, Includes the following steps: (1) Under a nitrogen protective atmosphere, the fluorinated diamine compound and the dialdehyde compound were dissolved separately in the same first organic solvent and stirred to dissolve, so as to obtain a solution of the fluorinated diamine compound and a solution of the dialdehyde compound. (2) Under a nitrogen protective atmosphere, the dialdehyde compound solution is added dropwise to the fluorinated diamine compound solution while it is being stirred. After the addition is complete, the reaction is stirred and then heated to maintain the temperature. (3) Pour the reaction solution obtained in step (2) into the precipitation solvent to precipitate the precipitate. The precipitate is washed, filtered, vacuum dried, ground and sieved to obtain the dynamic curing agent. (4) Mix the dynamic curing agent with the epoxy prepolymer, add a second organic solvent to the resulting mixture, preheat and stir until the curing agent is completely dissolved in the mixture system to obtain a clear mixture; (5) Pour the clarified mixture into a mold for vacuum degassing, then heat it for the first curing, and then continue to heat it for the second curing to obtain the self-healing insulating material for power module packaging.

6. The method for preparing a self-healing insulating material for power module packaging according to claim 5, characterized in that, In step (1), the molar ratio of the fluorinated diamine compound to the dialdehyde compound is (1.2~2):1; And / or, the first organic solvent is an anhydrous polar aprotic organic solvent, including at least one of anhydrous N,N-dimethylformamide, anhydrous N,N-dimethylacetamide, anhydrous dimethyl sulfoxide, and anhydrous N-methylpyrrolidone; And / or, the solid content of the fluorinated diamine compound solution is 30wt%~60wt%, and the solid content of the dialdehyde compound solution is 10wt%~40wt%.

7. The method for preparing a self-healing insulating material for power module packaging according to claim 5, characterized in that, In step (2), the dropping rate is 5~30 mL / min, and the stirring speed is 200~600 r / min; And / or, the temperature for continued stirring is room temperature, and the reaction time is 0.5~1h; And / or, the reaction temperature of the heat preservation reaction is 50~70℃, and the reaction time is 1~3h.

8. The method for preparing a self-healing insulating material for power module packaging according to claim 5, characterized in that, In step (3), the volume ratio of the reaction solution to the precipitating solvent is 1:(5~20); And / or, the precipitation solvent is deionized water; And / or, the vacuum drying temperature is 50~70℃, and the drying time is 12~36h; And / or, the sieving is through a 50-200 mesh sieve.

9. The method for preparing a self-healing insulating material for power module packaging according to claim 5, characterized in that, In step (4), the molar ratio of the active amine hydrogen in the dynamic curing agent to the epoxy group in the epoxy prepolymer is (0.95~1.05):1; And / or, the second organic solvent includes at least one of anhydrous N,N-dimethylformamide and anhydrous N,N-dimethylacetamide; the amount of the second organic solvent added is 10% to 30% of the total mass of the dynamic curing agent and the epoxy prepolymer; And / or, the preheating temperature is 80~130℃, and the preheating time is 20~50min.

10. The method for preparing a self-healing insulating material for power module packaging according to claim 5, characterized in that, In step (4), the vacuum degassing time is 2~10 min; And / or, the temperature of the first curing is 70~100℃, and the curing time is 8~12h; And / or, the temperature of the second curing is 130~160℃, and the curing time is 3~6h.

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