Chip inductance packaging material and preparation method thereof

Abstract

The application relates to the technical field of packaging materials, in particular to a chip inductance packaging material and a preparation method thereof. The packaging material is prepared from an epoxy resin as a matrix, and is compounded with boron nitride modified hollow glass microbeads, spherical silicon powder, a silane coupling agent, a curing agent, an accelerator and a defoaming agent. The boron nitride modified hollow glass microbeads are obtained by constructing a boron nitride functional layer through branched polyamidoamine grafting and a melamine-boric acid in-situ method, and are obtained through high-temperature calcination. The innovative structural design realizes efficient bonding of a filler interface and ordered construction of a heat conduction path, significantly improves the thermal conductivity and mechanical strength of the composite material, and effectively reduces the dielectric constant and dielectric loss. The packaging material provided by the application has excellent electrical, thermal and mechanical comprehensive performance, meets the lightweight and high-reliability packaging requirements of a new generation of high-performance chip inductance devices, and has important industrialization and application prospects.

Description

Technical Field

[0001] This invention relates to the field of packaging materials technology, and in particular to a chip inductor packaging material and its preparation method. Background Technology

[0002] With the booming development of emerging industries such as mobile communications, the Internet of Things, and new energy vehicles, chip inductors, as core passive electronic components, play crucial roles in circuits, including filtering, energy storage, and impedance matching, leading to an explosive growth in demand. Especially in high-frequency, high-power applications such as 5G communication base stations, smartphones, and electric vehicle power systems, chip inductors are facing trends towards miniaturization, high power density, and high frequency, placing increasingly stringent performance requirements on packaging materials.

[0003] Chip inductors generate significant magnetic field changes and eddy current losses during operation, leading to a rapid increase in device temperature. Unlike traditional integrated circuit packaging, chip inductor packaging materials must not only possess excellent thermal conductivity to effectively dissipate the heat generated by the device, but also maintain stable electrical performance in strong magnetic field environments. Under high-frequency operating conditions, changes in the dielectric loss and permeability of the packaging material directly affect the quality factor and operational stability of the inductor. Therefore, the packaging material is required to have a low dielectric constant, low dielectric loss, and good magnetic property stability.

[0004] Traditional electronic packaging materials are primarily designed for integrated circuit chips, whose performance specifications and application environments differ significantly from those of chip inductors. Chip inductor packaging materials need to ensure excellent thermal conductivity while also meeting several specific requirements, including mechanical strength, dielectric properties, thermal expansion matching, and magnetic field stability. Existing packaging materials typically employ composite systems of organic matrices such as epoxy resin and thermally conductive fillers, using inorganic fillers such as alumina, aluminum nitride, and boron nitride to enhance thermal conductivity. However, these traditional solutions have revealed numerous technical shortcomings in chip inductor applications.

[0005] Boron nitride (BN) is considered one of the most promising thermally conductive fillers due to its excellent thermal conductivity, superior electrical insulation, and good chemical stability. However, the application of BN fillers in chip inductor packaging materials faces severe challenges: First, BN powder is prone to agglomeration in polymer matrices, making it difficult to form a continuous and effective thermally conductive network, significantly reducing thermal conductivity. Second, BN has poor interfacial compatibility with organic matrices, easily leading to interfacial debonding under thermal cycling and mechanical stress, affecting packaging reliability. Furthermore, adding large amounts of BN fillers significantly deteriorates the material's processing performance and mechanical strength, hindering the mass production of chip inductors.

[0006] Hollow glass microspheres, as an emerging functional filler, have shown great application potential in chip inductor packaging materials due to their unique hollow structure and lightweight properties. The hollow structure not only effectively reduces material density and the weight of chip inductors, but also facilitates the control of dielectric properties and reduces high-frequency losses. However, the inherently low thermal conductivity of glass materials severely restricts the application of hollow glass microspheres in high-power chip inductor packaging. Simply increasing the filler content to compensate for insufficient thermal conductivity leads to a sharp increase in material viscosity, seriously affecting the operability of the packaging process.

[0007] Therefore, there is an urgent need to develop an innovative technical approach that can organically integrate the excellent thermal conductivity of boron nitride with the low dielectric properties of hollow glass microspheres, and achieve a performance breakthrough in chip inductor packaging materials through advanced interface engineering and structural design, so as to meet the packaging requirements of next-generation high-performance chip inductor devices. Summary of the Invention

[0008] In view of this, the purpose of this invention is to propose a chip inductor packaging material and its preparation method to solve the problem that existing electronic packaging materials cannot simultaneously achieve high thermal conductivity and low dielectric constant.

[0009] To achieve the above objectives, the present invention provides a chip inductor packaging material, which is prepared by weight from the following raw materials: 80-120 parts epoxy resin, 40-80 parts boron nitride modified hollow glass microspheres, 100-200 parts spherical silicon micropowder, 10-20 parts silane coupling agent, 20-40 parts curing agent, 0.6-1 part accelerator and 0.8-1.8 parts defoamer.

[0010] Preferably, the epoxy resin is one of epoxy resin E-51, epoxy resin HP-4032, and alicyclic epoxy resin TTA-21.

[0011] Preferably, the boron nitride modified hollow glass microspheres are obtained by calcining melamine borate formed in situ on branched polyamide amine grafted hollow glass microspheres using melamine and boric acid.

[0012] Preferably, the weight ratio of melamine, boric acid and branched polyamide amine grafted hollow glass microspheres is 44-82:75-110:50.

[0013] Preferably, the preparation method of the branched polyamide amine grafted hollow glass microspheres is as follows:

[0014] (1) Aminated hollow glass microspheres were obtained by grafting γ-aminopropyltrimethoxysilane onto hollow glass microspheres.

[0015] (2) Diethylenetriamine and methyl acrylate are grafted and crosslinked on the surface of aminated hollow glass microspheres to obtain branched polyamide amine grafted hollow glass microspheres.

[0016] Preferably, the average particle size of the hollow glass microspheres in step (1) is 10-50 μm.

[0017] Preferably, in step (1), the weight ratio of γ-aminopropyltrimethoxysilane to hollow glass microspheres is 1-10:50.

[0018] Preferably, in step (2), the weight ratio of diethylenetriamine, methyl acrylate and aminated hollow glass microspheres is 123-288:17-51:50.

[0019] Preferably, the specific preparation method of the boron nitride modified hollow glass microspheres is as follows: branched polyamide amine grafted hollow glass microspheres are added to deionized water and ultrasonically treated for 20-40 min. Then, boric acid and melamine are added, the temperature is raised to 93-97℃, stirred for 7-9 h, naturally cooled to room temperature, filtered, and vacuum dried to obtain melamine borate modified hollow glass microspheres. The melamine borate modified hollow glass microspheres are transferred to a tube furnace and heated to 1050-1150℃ at a rate of 8-12℃ / min under a nitrogen atmosphere and held for 3.5-4.5 h. Then, the temperature is lowered to 450-550℃ at a rate of 8-12℃ / min, and finally naturally cooled to room temperature to obtain boron nitride modified hollow glass microspheres.

[0020] Preferably, the average particle size of the spherical silica powder is 0.5-3 μm.

[0021] Preferably, the silane coupling agent is one or a mixture of several of γ-glycidoxypropyltrimethoxysilane, mercaptopropyltrimethoxysilane, and vinyltriethoxysilane.

[0022] Preferably, the curing agent is one of methyltetrahydrophthalic anhydride and methylhexahydrophthalic anhydride.

[0023] Preferably, the accelerator is one or a mixture of several of 2-ethyl-4-methylimidazole, 1-phenylimidazole and N-(2-hydroxyphenyl)-N',N'-dimethylurea.

[0024] Preferably, the defoamer is one or a mixture of several of BYK-066N, BYK-A530 and TEGO Foamex 810.

[0025] Furthermore, the present invention also provides a method for preparing a chip inductor packaging material, comprising the following steps:

[0026] S1: Dehydrate the epoxy resin, then add silane coupling agent and defoamer BYK-066N, stir, then add boron nitride modified hollow glass microspheres and spherical silica powder, stir, then add curing agent and accelerator, stir, vacuum degas, and obtain the adhesive.

[0027] S2: The adhesive is poured into the chip inductor mold. After pouring, it is thermosetting, demolded, heat-treated, and naturally cooled to room temperature to obtain the chip inductor packaging material.

[0028] Preferably, in step S1, the vacuum degassing is carried out at a vacuum of -0.095 MPa for 30-50 minutes.

[0029] Preferably, the infusion rate in step S2 is 4-6 mL / s and the pressure is 0.15-0.25 MPa.

[0030] Preferably, in step S2, the thermosetting process involves first curing at 78-82°C for 1-2 hours, and then curing at 133-137°C for 1.5-2.5 hours.

[0031] Preferably, the heat treatment in step S2 is performed at 145-155°C for 3-5 hours.

[0032] The beneficial effects of this invention are:

[0033] This invention utilizes an innovative in-situ generation technology to construct a boron nitride functional modification layer on the surface of hollow glass microspheres, achieving an organic unity between filler structure design and interface engineering, and bringing significant technical advantages and application value.

[0034] The branched polyamide amine grafting modification technology employed in this invention introduces abundant amine functional groups and multi-branched molecular chain structures onto the surface of hollow glass microspheres, providing an ideal reaction platform for the subsequent in-situ generation of boron nitride. This molecular design not only increases the density of surface reactive sites but also achieves the ordered arrangement of precursor molecules through spatial configuration control of molecular chains, providing a good template effect for the nucleation and growth of boron nitride crystals. The in-situ generated boron nitride modified layer forms a strong chemical bond with the glass substrate, effectively eliminating the interfacial thermal resistance problem commonly found in traditional physical mixing methods. This chemical bond not only improves the interfacial bonding strength but also ensures efficient heat transfer within the filler network, significantly enhancing the thermal conductivity of the composite material. Simultaneously, the molecular-level mixing and reaction control during the in-situ generation process result in a continuous and uniform microstructure in the boron nitride modified layer, avoiding the problems of filler agglomeration and uneven dispersion in traditional methods.

[0035] Regarding dielectric properties, this invention achieves effective regulation of the dielectric constant by precisely controlling the structure of the boron nitride modified layer. The in-situ generated boron nitride layer possesses good crystallinity and an ordered structure, reducing dielectric loss and polarization effects, and ensuring the stability of the material under high-frequency electric field environments. The presence of the hollow structure further reduces the dielectric constant of the material, meeting the requirements of electronic packaging materials for low dielectric properties.

[0036] In summary, this invention achieves synergistic optimization of thermal conductivity, mechanical strength, and dielectric properties through technological innovation, opening up a new technological path for the development of high-performance lightweight electronic packaging materials, and has significant scientific value and broad application prospects. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0038] Example 1:

[0039] (1) Add 50g of hollow glass microspheres (average particle size of 20μm) to a mixed solvent of 300g of anhydrous ethanol and 700g of deionized water, sonicate for 20min, then add 1g of γ-aminopropyltrimethoxysilane, heat to 53℃, stir for 5h, centrifuge, wash 3 times each with deionized water and anhydrous ethanol, and vacuum dry to obtain aminated hollow glass microspheres;

[0040] (2) Add 50g of aminated hollow glass microspheres to 123g of diethylenetriamine, sonicate for 30min, then add 17g of methyl acrylate and 300g of methanol, stir at room temperature for 5h, then heat to remove methanol, heat to 148℃, stir for 20h, centrifuge, wash 3 times with N,N-dimethylacetamide, and vacuum dry to obtain branched polyamide-amine grafted hollow glass microspheres;

[0041] (3) Add 50g of branched polyamide amine grafted hollow glass microspheres to 4000g of deionized water, sonicate for 20min, then add 75g of boric acid and 44g of melamine, heat to 93℃, stir for 7h, cool naturally to room temperature, filter, and vacuum dry to obtain melamine borate modified hollow glass microspheres.

[0042] (4) The melamine borate modified hollow glass microspheres were transferred to a tube furnace and heated to 1050°C at a rate of 8°C / min under a nitrogen atmosphere and held for 3.5 h. Then the temperature was reduced to 450°C at a rate of 8°C / min and finally cooled to room temperature naturally to obtain boron nitride modified hollow glass microspheres.

[0043] (5) Dehydrate 80g of epoxy resin E-51 at 80℃ for 1h, then transfer it to a vacuum mixer, add 10g of γ-glycidyl etheroxypropyltrimethoxysilane and 0.8g of defoamer BYK-066N, stir at 400rpm for 20min, add 40g of boron nitride modified hollow glass microspheres and 100g of spherical silica powder (average particle size 1μm), stir at 700rpm for 15min, add 20g of acid anhydride curing agent methyltetrahydrophthalic anhydride and 0.6g of accelerator 2-ethyl-4-methylimidazolium, stir at 150rpm for 3min, and finally keep under a vacuum of -0.095MPa for 30min to obtain the adhesive.

[0044] (6) The adhesive is injected into the chip inductor mold preheated to 65°C at a rate of 4 mL / s and a pressure of 0.15 MPa. After injection, it is cured at 78°C for 1 h, then heated to 133°C and cured for 1.5 h. Then it is cooled to 55°C at a rate of 0.5°C / min and demolded. The cured package is placed in a 145°C oven for 3 h and then naturally cooled to room temperature to obtain the chip inductor packaging material.

[0045] Example 2:

[0046] (1) Add 50g of hollow glass microspheres (average particle size of 20μm) to a mixed solvent of 300g of anhydrous ethanol and 700g of deionized water, sonicate for 30min, then add 5g of γ-aminopropyltrimethoxysilane, heat to 55℃, stir for 6h, centrifuge, wash 3 times each with deionized water and anhydrous ethanol, and vacuum dry to obtain aminated hollow glass microspheres;

[0047] (2) Add 50g of aminated hollow glass microspheres to 206g of diethylenetriamine, sonicate for 30min, then add 34g of methyl acrylate and 500g of methanol, stir at room temperature for 6h, then heat to remove methanol, heat to 150℃, stir for 24h, centrifuge, wash 3 times with N,N-dimethylacetamide, and vacuum dry to obtain branched polyamide-amine grafted hollow glass microspheres;

[0048] (3) Add 50g of branched polyamide amine grafted hollow glass microspheres to 5000g of deionized water, sonicate for 30min, then add 92.8g of boric acid and 63g of melamine, heat to 95℃, stir for 8h, cool naturally to room temperature, filter, and vacuum dry to obtain melamine borate modified hollow glass microspheres.

[0049] (4) The melamine borate modified hollow glass microspheres were transferred to a tube furnace and heated to 1100℃ at a rate of 10℃ / min under a nitrogen atmosphere and held for 4 hours. Then the temperature was reduced to 500℃ at a rate of 10℃ / min and finally cooled to room temperature naturally to obtain boron nitride modified hollow glass microspheres.

[0050] (5) 100g of epoxy resin E-51 was dehydrated at 85℃ for 1.5h, then transferred to a vacuum mixer, 15g of γ-glycidyl etheroxypropyltrimethoxysilane and 1.2g of defoamer BYK-066N were added, and stirred at 500rpm for 30min. Then 60g of boron nitride modified hollow glass microspheres and 140g of spherical silica powder (average particle size 1μm) were added, and stirred at 800rpm for 20min. Then 30g of acid anhydride curing agent methyltetrahydrophthalic anhydride and 0.8g of accelerator 2-ethyl-4-methylimidazolium were added, and stirred at 200rpm for 5min. Finally, the mixture was kept under a vacuum of -0.095MPa for 40min to obtain the adhesive.

[0051] (6) Inject the adhesive into the chip inductor mold preheated to 70°C at a rate of 5 mL / s and a pressure of 0.2 MPa. After injection, cure at 80°C for 1.5 h, then heat to 135°C and cure for 2 h. Then cool down to 60°C at a rate of 1°C / min and demold. Place the cured package in a 150°C oven for 4 h and allow it to cool naturally to room temperature to obtain the chip inductor packaging material.

[0052] Example 3:

[0053] (1) Add 50g of hollow glass microspheres (average particle size of 20μm) to a mixed solvent of 300g of anhydrous ethanol and 700g of deionized water, sonicate for 40min, then add 10g of γ-aminopropyltrimethoxysilane, heat to 57℃, stir for 7h, centrifuge, wash 3 times each with deionized water and anhydrous ethanol, and vacuum dry to obtain aminated hollow glass microspheres.

[0054] (2) Add 50g of aminated hollow glass microspheres to 288g of diethylenetriamine, sonicate for 30min, then add 51g of methyl acrylate and 800g of methanol, stir at room temperature for 7h, then heat to remove methanol, heat to 152℃, stir for 28h, centrifuge, wash 3 times with N,N-dimethylacetamide, and vacuum dry to obtain branched polyamide-amine grafted hollow glass microspheres;

[0055] (3) Add 50g of branched polyamide amine grafted hollow glass microspheres to 6000g of deionized water, sonicate for 40min, then add 110g of boric acid and 82g of melamine, heat to 97℃, stir for 9h, cool naturally to room temperature, filter, and vacuum dry to obtain melamine borate modified hollow glass microspheres.

[0056] (4) The melamine borate modified hollow glass microspheres were transferred to a tube furnace and heated to 1150°C at a rate of 12°C / min under a nitrogen atmosphere and held for 4.5 h. Then the temperature was reduced to 550°C at a rate of 12°C / min and finally cooled to room temperature to obtain boron nitride modified hollow glass microspheres.

[0057] (5) Dehydrate 120g of epoxy resin E-51 at 90℃ for 2h, then transfer it to a vacuum mixer, add 20g of γ-glycidyl etheroxypropyltrimethoxysilane and 1.8g of defoamer BYK-066N, stir at 600rpm for 40min, add 80g of boron nitride modified hollow glass microspheres and 200g of spherical silica powder (average particle size 1μm), stir at 1000rpm for 25min, add 40g of acid anhydride curing agent methyltetrahydrophthalic anhydride and 1g of accelerator 2-ethyl-4-methylimidazolium, stir at 250rpm for 8min, and finally keep under a vacuum of -0.095MPa for 30-50min to obtain the adhesive.

[0058] (6) The adhesive is injected into the chip inductor mold preheated to 75°C at a rate of 6 mL / s and a pressure of 0.25 MPa. After injection, it is cured at 82°C for 2 hours, then heated to 137°C and cured for 2.5 hours. Then it is cooled to 65°C at a rate of 2°C / min and demolded. The cured package is placed in a 155°C oven for 5 hours and then cooled naturally to room temperature to obtain the chip inductor packaging material.

[0059] Comparative Example 1:

[0060] The difference between Comparative Example 1 and Example 2 is that the branched polyamide amine grafted hollow glass microspheres in step (3) are replaced with aminated hollow glass microspheres.

[0061] The specific steps are as follows:

[0062] (1) Add 50g of hollow glass microspheres (average particle size of 20μm) to a mixed solvent of 300g of anhydrous ethanol and 700g of deionized water, sonicate for 30min, then add 5g of γ-aminopropyltrimethoxysilane, heat to 55℃, stir for 6h, centrifuge, wash 3 times each with deionized water and anhydrous ethanol, and vacuum dry to obtain aminated hollow glass microspheres;

[0063] (2) Add 50g of aminated hollow glass microspheres to 5000g of deionized water, sonicate for 30min, then add 92.8g of boric acid and 63g of melamine, heat to 95℃, stir for 8h, cool naturally to room temperature, filter, and vacuum dry to obtain melamine borate modified hollow glass microspheres.

[0064] (3) The melamine borate modified hollow glass microspheres were transferred to a tube furnace and heated to 1100℃ at a rate of 10℃ / min under a nitrogen atmosphere and held for 4 hours. Then the temperature was reduced to 500℃ at a rate of 10℃ / min and finally cooled to room temperature to obtain boron nitride modified hollow glass microspheres.

[0065] (4) 100g of epoxy resin E-51 was dehydrated at 85℃ for 1.5h, then transferred to a vacuum mixer, 15g of γ-glycidyl etheroxypropyltrimethoxysilane and 1.2g of defoamer BYK-066N were added, and stirred at 500rpm for 30min. Then 60g of boron nitride modified hollow glass microspheres and 140g of spherical silica powder (average particle size 1μm) were added, and stirred at 800rpm for 20min. Then 30g of acid anhydride curing agent methyltetrahydrophthalic anhydride and 0.8g of accelerator 2-ethyl-4-methylimidazolium were added, and stirred at 200rpm for 5min. Finally, the mixture was kept under a vacuum of -0.095MPa for 40min to obtain the adhesive.

[0066] (5) Inject the adhesive into the chip inductor mold preheated to 70°C at a rate of 5 mL / s and a pressure of 0.2 MPa. After injection, cure at 80°C for 1.5 h, then raise the temperature to 135°C and cure for 2 h. Then cool down to 60°C at a rate of 1°C / min and demold. Place the cured package in a 150°C oven for 4 h and allow it to cool naturally to room temperature to obtain the encapsulation material.

[0067] Comparative Example 2:

[0068] The difference between Comparative Example 2 and Example 2 is that the branched polyamide amine grafted hollow glass microspheres in step (3) are replaced with hollow glass microspheres;

[0069] The specific steps are as follows:

[0070] (1) Add 50g of hollow glass microspheres (average particle size of 20μm) to 5000g of deionized water, sonicate for 30min, then add 92.8g of boric acid and 63g of melamine, heat to 95℃, stir for 8h, cool naturally to room temperature, filter, and vacuum dry to obtain melamine borate modified hollow glass microspheres.

[0071] (2) The melamine borate modified hollow glass microspheres were transferred to a tube furnace and heated to 1100℃ at a rate of 10℃ / min under a nitrogen atmosphere and held for 4h. Then the temperature was reduced to 500℃ at a rate of 10℃ / min and finally cooled to room temperature naturally to obtain boron nitride modified hollow glass microspheres.

[0072] (3) 100g of epoxy resin E-51 was dehydrated at 85℃ for 1.5h, then transferred to a vacuum mixer, 15g of γ-glycidyl etheroxypropyltrimethoxysilane and 1.2g of defoamer BYK-066N were added, and stirred at 500rpm for 30min. Then 60g of boron nitride modified hollow glass microspheres and 140g of spherical silica powder (average particle size 1μm) were added, and stirred at 800rpm for 20min. Then 30g of acid anhydride curing agent methyltetrahydrophthalic anhydride and 0.8g of accelerator 2-ethyl-4-methylimidazolium were added, and stirred at 200rpm for 5min. Finally, the mixture was kept under a vacuum of -0.095MPa for 40min to obtain the adhesive.

[0073] (4) Inject the adhesive into the chip inductor mold preheated to 70°C at a rate of 5 mL / s and a pressure of 0.2 MPa. After injection, cure at 80°C for 1.5 h, then raise the temperature to 135°C and cure for 2 h. Then cool down to 60°C at a rate of 1°C / min and demold. Place the cured package in a 150°C oven for 4 h and allow it to cool naturally to room temperature to obtain the encapsulation material.

[0074] Comparative Example 3:

[0075] The difference between Comparative Example 3 and Example 2 is that the boron nitride modified hollow glass microspheres in step (5) are replaced with hollow glass microspheres;

[0076] The specific steps are as follows:

[0077] (1) 100g of epoxy resin E-51 was dehydrated at 85℃ for 1.5h, then transferred to a vacuum mixer, 15g of γ-glycidyl etheroxypropyltrimethoxysilane and 1.2g of defoamer BYK-066N were added, and stirred at 500rpm for 30min. Then 60g of hollow glass microspheres (average particle size of 20μm) and 140g of spherical silica powder (average particle size of 1μm) were added, and stirred at 800rpm for 20min. Then 30g of acid anhydride curing agent methyltetrahydrophthalic anhydride and 0.8g of accelerator 2-ethyl-4-methylimidazolium were added, and stirred at 200rpm for 5min. Finally, the mixture was kept under a vacuum of -0.095MPa for 40min to obtain the adhesive.

[0078] (2) The adhesive is injected into the chip inductor mold preheated to 70°C at a rate of 5 mL / s and a pressure of 0.2 MPa. After injection, it is cured at 80°C for 1.5 h, then heated to 135°C and cured for 2 h. Then it is cooled to 60°C at a rate of 1°C / min and demolded. The cured package is placed in a 150°C oven for 4 h and then naturally cooled to room temperature to obtain the encapsulation material.

[0079] Comparative Example 4:

[0080] The difference between Comparative Example 4 and Example 2 is that the boron nitride modified hollow glass microspheres in step (5) are replaced with boron nitride;

[0081] The specific steps are as follows:

[0082] (1) Add 92.8g of boric acid and 63g of melamine to 5000g of deionized water, heat to 95℃, stir for 8h, cool naturally to room temperature, filter, and vacuum dry to obtain melamine borate.

[0083] (2) Melamine borate was transferred to a tube furnace and heated to 1100°C at a rate of 10°C / min under a nitrogen atmosphere and held for 4 hours. Then it was cooled to 500°C at a rate of 10°C / min and finally cooled to room temperature to obtain boron nitride.

[0084] (3) 100g of epoxy resin E-51 was dehydrated at 85℃ for 1.5h, then transferred to a vacuum mixer, 15g of γ-glycidyl etheroxypropyltrimethoxysilane and 1.2g of defoamer BYK-066N were added, and stirred at 500rpm for 30min. Then 60g of boron nitride and 140g of spherical silica powder (average particle size 1μm) were added, and stirred at 800rpm for 20min. Then 30g of acid anhydride curing agent methyltetrahydrophthalic anhydride and 0.8g of accelerator 2-ethyl-4-methylimidazolium were added, and stirred at 200rpm for 5min. Finally, the mixture was kept under a vacuum of -0.095MPa for 40min to obtain the adhesive.

[0085] (4) Inject the adhesive into the chip inductor mold preheated to 70°C at a rate of 5 mL / s and a pressure of 0.2 MPa. After injection, cure at 80°C for 1.5 h, then raise the temperature to 135°C and cure for 2 h. Then cool down to 60°C at a rate of 1°C / min and demold. Place the cured package in a 150°C oven for 4 h and allow it to cool naturally to room temperature to obtain the encapsulation material.

[0086] Performance testing:

[0087] Thermal conductivity test: Referring to GB / T 10297-2015, a thermal conductivity meter was used. Under a constant temperature environment of 25℃, the hot wire sensor was placed on two parallel samples (20×20×5mm). 3 Between 2.0W and 3.0W, a constant power of 2.0W was applied, and the temperature rise curve was recorded within 60s. The thermal conductivity was calculated, and the results are shown in Table 1.

[0088] Mechanical strength test: Referring to GB / T 9341-2008, a microcomputer-controlled electronic universal testing machine was used in three-point bending mode with a span of 64 mm and a loading rate of 2 mm / min. The maximum load at which the specimen broke was recorded, and the bending strength was calculated. The results are shown in Table 1.

[0089] Dielectric constant test: Referring to GB / T 1409-2006, a broadband impedance analyzer was used. The sample was placed between parallel plate electrodes, and a constant pressure of 0.5N was applied to ensure uniform electrode contact. The scanning mode was selected as single frequency point test, the frequency was set to 1.000MHz, the measurement mode was Cp-D, and the capacitance value was read after stabilization. The dielectric constant was calculated, and the results are shown in Table 1.

[0090] Table 1 Performance Test Results

[0091] thermal conductivity Bending strength Dielectric constant Example 1 2.4 142 2.8 Example 2 2.6 155 2.7 Example 3 2.9 138 2.5 Comparative Example 1 2.2 135 3.0 Comparative Example 2 1.9 122 3.2 Comparative Example 3 0.4 104 2.5 Comparative Example 4 2.9 93 3.8

[0092] Data Analysis:

[0093] As can be seen from the data in Example 2 of Table 1, the chip inductor packaging material prepared by this invention exhibits excellent overall performance balance. This may be attributed to the unique structural advantages brought about by the in-situ generation mechanism of boron nitride on the surface of branched polyamide amine modified microspheres. The abundant amino functional groups in the branched polyamide amine molecular chain may provide uniformly distributed nucleation sites for the melamine borate precursor, guiding the orderly growth of boron nitride crystals during high-temperature nitriding, forming a surface modified layer with good crystallinity and morphology control. This in-situ generated boron nitride layer may establish strong chemical bonds with the glass substrate, effectively eliminating the interfacial thermal resistance and stress concentration problems common in traditional physical mixing. At the same time, the multi-branched structure of the branched polyamide amine may play a structural guiding and stabilizing role in the boron nitride generation process through molecular chain entanglement and hydrogen bonding interactions, ensuring the continuity and integrity of the modified layer.

[0094] As can be seen from the data in Table 1 for Example 2 and Comparative Example 1, the branched polyamide amine graft modification showed a significant improvement in all performance indicators compared to simple amylation modification. This indicates that the molecular structure design of branched polyamide amine plays an important role in optimizing the generation and dispersion of boron nitride. In Comparative Example 1, only aminated hollow glass microspheres were used, and the density and spatial distribution of their surface amino functional groups may be relatively limited. This results in a lack of sufficient reactive sites when interacting with the melamine borate precursor, leading to uneven nucleation density of boron nitride and potentially causing problems such as inconsistent thickness and structural defects in the resulting modified layer.

[0095] As can be seen from the data in Table 1 for Example 2 and Comparative Example 2, the dual surface modification of aminated and branched polyamide amines played a crucial role in improving performance compared to unmodified treatment. This stepwise functionalization modification strategy may create ideal conditions for the effective generation and structural regulation of boron nitride. Comparative Example 2 directly used original hollow glass microspheres, whose surfaces lack organic functional groups and reactive sites. The melamine borate precursor mainly adhered to the surface of the microspheres through physical adsorption. This weak interaction may lead to uneven distribution of the precursor, making it prone to desorption and aggregation during subsequent high-temperature nitriding, affecting the continuity and stability of the boron nitride modified layer.

[0096] As can be seen from the data in Table 1 for Example 2 and Comparative Example 3, the presence of the boron nitride surface modification layer plays a decisive role in improving the thermal conductivity of the material. This significant performance difference reveals the important role of boron nitride as a thermally conductive functional component in composite materials. Comparative Example 3 uses hollow glass microspheres without boron nitride modification. The thermal conductivity of the material mainly depends on the thermal conductivity of the glass substrate itself, while the inherent low thermal conductivity of the glass material limits the overall thermal conductivity of the composite material. Although the hollow structure helps to reduce the weight of the material, it also further reduces the effective thermal cross-sectional area, resulting in lower heat transfer efficiency. In Example 2, the in-situ generated boron nitride modification layer may have constructed continuous high thermal conductivity channels on the surface of the microspheres. The hexagonal lattice structure and strong covalent bond characteristics of boron nitride endow it with excellent phonon transport capabilities, which can effectively improve the heat transfer efficiency on the surface of the filler particles. The in-situ generated boron nitride may have formed a good interfacial bond with the glass substrate, reducing the influence of interfacial thermal resistance, allowing heat to be smoothly transferred in the filler network. Meanwhile, the boron nitride modified layer may also have a positive impact on the mechanical properties of the composite material by improving the chemical compatibility and interfacial bonding strength of the filler surface, thus achieving synergistic optimization of thermal conductivity and mechanical strength.

[0097] As can be seen from the data in Table 1 for Example 2 and Comparative Example 4, boron nitride-modified hollow glass microspheres exhibit significant technical advantages over adding boron nitride powder alone in terms of overall performance optimization, particularly in the balanced control of mechanical strength and dielectric properties. While Comparative Example 4 showed good thermal conductivity, the significant decrease in mechanical strength and the significant increase in dielectric constant indicate that independent boron nitride filler suffers from dispersibility and interfacial compatibility issues. As an independent filler component, boron nitride powder may form local agglomerates and stress concentrations in the composite matrix. These structural defects not only affect the uniform transmission of stress but may also generate polarization effects under an electric field, leading to increased dielectric loss. In contrast, the boron nitride in Example 2, through in-situ generation, forms an integrated composite filler structure with the hollow glass microspheres, potentially achieving a more uniform dispersion and optimized interfacial characteristics. The in-situ generated boron nitride-modified layer not only maintains good thermal conductivity but also enhances the structural integrity and interfacial stability of the filler through chemical bonding with the glass substrate and molecular bridging with branched polyamide amine. This design may effectively avoid the agglomeration problem and interface defects caused by the addition of boron nitride powder. While achieving excellent thermal conductivity, it maintains high mechanical strength and low dielectric constant, realizing the coordinated optimization of multiple properties and better meeting the application requirements of electronic packaging materials.

[0098] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A chip inductor packaging material, characterized in that, The product is prepared by weight from the following raw materials: 80-120 parts epoxy resin, 40-80 parts boron nitride modified hollow glass microspheres, 100-200 parts spherical silica powder, 10-20 parts silane coupling agent, 20-40 parts curing agent, 0.6-1 part accelerator and 0.8-1.8 parts defoamer; The boron nitride modified hollow glass microspheres are obtained by calcining melamine borate formed in situ on branched polyamide amine grafted hollow glass microspheres with melamine and boric acid.

2. The chip inductor packaging material according to claim 1, characterized in that, The epoxy resin is one of epoxy resin E-51, epoxy resin HP-4032, and alicyclic epoxy resin TTA-21.

3. The chip inductor packaging material according to claim 1, characterized in that, The weight ratio of melamine, boric acid and branched polyamide amine grafted hollow glass microspheres is 44-82:75-110:

50.

4. The chip inductor packaging material according to claim 1, characterized in that, The method for preparing the branched polyamide amine grafted hollow glass microspheres includes the following steps: (1) Aminated hollow glass microspheres were obtained by grafting γ-aminopropyltrimethoxysilane onto hollow glass microspheres. (2) Diethylenetriamine and methyl acrylate are grafted and crosslinked on the surface of aminated hollow glass microspheres to obtain branched polyamide amine grafted hollow glass microspheres.

5. The chip inductor packaging material according to claim 4, characterized in that, In step (1), the weight ratio of γ-aminopropyltrimethoxysilane to hollow glass microspheres is 1-10:50; in step (2), the weight ratio of diethylenetriamine, methyl acrylate and aminated hollow glass microspheres is 123-288:17-51:

50.

6. The chip inductor packaging material according to claim 1, characterized in that, The silane coupling agent is one or a mixture of several of γ-glycidoxypropyltrimethoxysilane, mercaptopropyltrimethoxysilane, and vinyltriethoxysilane.

7. The chip inductor packaging material according to claim 1, characterized in that, The curing agent is one of methyltetrahydrophthalic anhydride and methylhexahydrophthalic anhydride.

8. The chip inductor packaging material according to claim 1, characterized in that, The accelerator is one or a mixture of several of 2-ethyl-4-methylimidazole, 1-phenylimidazole and N-(2-hydroxyphenyl)-N',N'-dimethylurea.

9. The chip inductor packaging material according to claim 1, characterized in that, The defoamer is one or a mixture of several of BYK-066N, BYK-A530 and TEGO Foamex 810.

10. A method for preparing a chip inductor packaging material according to any one of claims 1-9, characterized in that, Includes the following steps: S1: Dehydrate the epoxy resin, then add silane coupling agent and defoamer BYK-066N, stir, then add boron nitride modified hollow glass microspheres and spherical silica powder, stir, then add curing agent and accelerator, stir, vacuum degas, and obtain the adhesive. S2: The adhesive is poured into the chip inductor mold. After pouring, it is thermosetting, demolded, heat-treated, and naturally cooled to room temperature to obtain the chip inductor packaging material.