Chip inductor packaging material and preparation method thereof

Abstract

The invention relates to the technical field of packaging materials, in particular to a chip inductor packaging material and a preparation method thereof. The packaging material is prepared from epoxy resin serving as a matrix, composite boron nitride modified hollow glass beads, spherical silica powder, a silane coupling agent, a curing agent, an accelerant and a defoaming agent. Wherein the boron nitride modified hollow glass beads are obtained by constructing a boron nitride functional layer through branched polyamidoamine grafting and a melamine-boric acid in-situ method and carrying out high-temperature calcination. By means of the innovative structural design, efficient bonding of a filler interface and ordered construction of a heat conduction path are achieved, the heat conduction performance and the mechanical strength of the composite material are remarkably improved, and the dielectric constant and the dielectric loss are effectively reduced. The packaging material provided by the invention has excellent electrical, thermal and mechanical comprehensive performance, meets the requirements of light weight and high reliability packaging of a new generation of high-performance chip inductor devices, and has important industrialization and application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of packaging materials, and in particular to a chip inductor packaging material and a preparation method thereof. Background Art

[0002] With the rapid development of emerging industries such as mobile communications, the Internet of Things, and new energy vehicles, chip inductors, as core passive electronic components, perform key functions in circuits such as filtering, energy storage, and impedance matching, and their demand has seen explosive growth. In high-frequency, high-power applications such as 5G communication base stations, smartphones, and electric vehicle power systems, chip inductors are facing the development trend of miniaturization, high power density, and high frequency, placing more stringent performance requirements on packaging materials.

[0003] Chip inductors generate significant magnetic field fluctuations and eddy current losses during operation, causing 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 device heat but also maintain stable electrical performance in strong magnetic fields. Under high-frequency operating conditions, the dielectric loss and permeability variations of the packaging material directly affect the quality factor and operational stability of the inductor. Therefore, packaging materials with a low dielectric constant, low dielectric loss, and good magnetic stability are required.

[0004] Traditional electronic packaging materials are primarily designed for integrated circuit chips, and their performance metrics and application environments differ significantly from those of chip inductor devices. Chip inductor packaging materials must ensure excellent thermal conductivity while also meeting numerous special requirements, including mechanical strength, dielectric properties, thermal expansion compatibility, and magnetic field stability. Existing packaging materials typically utilize a composite system combining an organic matrix like epoxy resin with a thermally conductive filler. Thermal conductivity is enhanced by the addition of inorganic fillers such as aluminum oxide, aluminum nitride, and boron nitride. However, these traditional solutions exhibit numerous technical drawbacks in chip inductor applications.

[0005] Boron nitride (BN) is considered one of the most promising thermally conductive fillers due to its exceptional thermal conductivity, excellent electrical insulation, and good chemical stability. However, its application in chip inductor packaging materials faces significant challenges: First, BN powder easily agglomerates within the polymer matrix, making it difficult to form a continuous and effective thermal network, significantly reducing thermal conductivity. Second, BN exhibits poor interfacial compatibility with the organic matrix, leading to interfacial debonding under thermal cycling and mechanical stress, compromising packaging reliability. Furthermore, the addition of large amounts of BN filler significantly degrades the material's processing properties and mechanical strength, hindering the mass production of chip inductors.

[0006] As an emerging functional filler, hollow glass microspheres, with their unique hollow structure and lightweight properties, show great potential for application in chip inductor packaging. This hollow structure not only effectively reduces material density and weight, but also facilitates the manipulation of dielectric properties and reduces high-frequency losses. However, the inherent low thermal conductivity of glass severely restricts the application of hollow glass microspheres in high-power chip inductor packaging. Simply increasing the filler dosage to compensate for the lack of thermal conductivity can lead to a sharp increase in material viscosity, severely impacting the operability of the packaging process.

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

[0008] In view of this, the object of the present invention is to provide a chip inductor packaging material and a preparation method thereof, so as to solve the problem that existing electronic packaging materials are difficult to achieve high thermal conductivity and low dielectric constant at the same time.

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

[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 in-situ generating melamine borate from melamine and boric acid on branched polyamidoamine grafted hollow glass microspheres, followed by calcination.

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

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

[0014] (1) Using γ-aminopropyltrimethoxysilane to graft hollow glass microspheres to obtain amino-modified hollow glass microspheres;

[0015] (2) Diethylenetriamine and methyl acrylate are grafted and cross-linked 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 amino 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: adding branched polyamide amine grafted hollow glass microspheres to deionized water, ultrasonically treating for 20-40 minutes, then adding boric acid and melamine, heating to 93-97°C, stirring for 7-9 hours, naturally cooling to room temperature, filtering, and vacuum drying to obtain melamine borate modified hollow glass microspheres; transferring the melamine borate modified hollow glass microspheres to a tube furnace, heating to 1050-1150°C at a rate of 8-12°C / min under a nitrogen atmosphere and keeping the temperature for 3.5-4.5 hours, then cooling to 450-550°C at a rate of 8-12°C / min, and finally naturally cooling to room temperature to obtain boron nitride modified hollow glass microspheres.

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

[0021] Preferably, the silane coupling agent is one or a mixture of γ-glycidyloxypropyltrimethoxysilane, 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 2-ethyl-4-methylimidazole, 1-phenylimidazole and N-(2-hydroxyphenyl)-N',N'-dimethylurea.

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

[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, add a silane coupling agent and a defoamer BYK-066N, stir, add boron nitride-modified hollow glass microspheres and spherical silica powder, stir, add a curing agent and an accelerator, stir, and vacuum degas to obtain a rubber compound;

[0027] S2: pouring the glue into the chip inductor mold. After the pouring is completed, heat curing, demoulding, heat treatment, and natural cooling to room temperature are performed to obtain the chip inductor packaging material.

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

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

[0030] Preferably, the thermal curing in step S2 is 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] Beneficial effects of the present invention:

[0033] The present invention constructs a boron nitride functional modification layer on the surface of hollow glass microspheres through innovative in-situ generation technology, realizes the organic unity of filler structure design and interface engineering, and brings significant technical advantages and application value.

[0034] The branched polyamide amine grafting modification technology adopted in the present invention introduces rich amino functional groups and multi-branched molecular chain structures on 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 reaction active sites, but also achieves an orderly arrangement of precursor molecules through spatial configuration regulation of the molecular chain, providing a good template effect for the nucleation and growth of boron nitride crystals. A strong chemical bond is formed between the in-situ generated boron nitride modified layer and the glass substrate, effectively eliminating the interfacial thermal resistance problem common in traditional physical mixing methods. This chemical bonding not only improves the interfacial bonding strength, but also ensures the efficient transfer of heat in the filler network, significantly improving the thermal conductivity of the composite material. At the same time, the molecular-level mixing and reaction control during the in-situ generation process give the boron nitride modified layer a continuous and uniform microstructural feature, avoiding the problems of filler agglomeration and uneven dispersion in traditional methods.

[0035] In terms of 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 exhibits excellent crystallinity and an ordered structure, reducing dielectric loss and polarization effects, ensuring stable performance in high-frequency electric fields. The presence of the hollow structure further reduces the dielectric constant, meeting the low dielectric performance requirements of electronic packaging materials.

[0036] In summary, the present invention achieves the synergistic optimization of thermal conductivity, mechanical strength and dielectric properties through technological innovation, opens up a new technical path for the development of high-performance lightweight electronic packaging materials, and has important scientific significance and broad application prospects. DETAILED DESCRIPTION

[0037] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to specific embodiments.

[0038] Example 1:

[0039] (1) 50 g of hollow glass microspheres (average particle size of 20 μm) were added to a mixed solvent of 300 g of anhydrous ethanol and 700 g of deionized water, ultrasonicated for 20 min, and then 1 g of γ-aminopropyltrimethoxysilane was added. The temperature was raised to 53 ° C. and stirred for 5 h. The mixture was centrifuged and washed with deionized water and anhydrous ethanol three times each. The mixture was vacuum dried to obtain amino-modified hollow glass microspheres.

[0040] (2) 50 g of aminated hollow glass microspheres were added to 123 g of diethylenetriamine, ultrasonically treated for 30 min, and then 17 g of methyl acrylate and 300 g of methanol were added. The mixture was stirred and reacted at room temperature for 5 h. The methanol was then removed by heating to 148 ° C. The mixture was stirred and reacted for 20 h. The mixture was centrifuged, washed with N, N-dimethylacetamide three times, and vacuum dried to obtain branched polyamidoamine grafted hollow glass microspheres.

[0041] (3) 50 g of branched polyamide-grafted hollow glass microspheres were added to 4000 g of deionized water, ultrasonically treated for 20 min, and then 75 g of boric acid and 44 g of melamine were added. The temperature was raised to 93 ° C. and stirred for 7 h. The mixture was naturally cooled to room temperature, filtered, and vacuum dried to obtain melamine borate-modified hollow glass microspheres.

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

[0043] (5) 80 g of epoxy resin E-51 was dehydrated at 80 ° C for 1 h, then transferred to a vacuum stirring kettle, and then 10 g of γ-glycidyloxypropyltrimethoxysilane and 0.8 g of defoamer BYK-066N were added, and stirred at a speed of 400 rpm for 20 min. Then, 40 g of boron nitride modified hollow glass microspheres and 100 g of spherical silica powder (average particle size 1 μm) were added, and stirred at a speed of 700 rpm for 15 min. Then, 20 g of anhydride curing agent methyltetrahydrophthalic anhydride and 0.6 g of accelerator 2-ethyl-4-methylimidazole were added, and stirred at a speed of 150 rpm for 3 min. Finally, the mixture was kept at a vacuum degree of -0.095 MPa for 30 min to obtain a rubber compound;

[0044] (6) The adhesive was 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 the injection was completed, it was cured at 78°C for 1 hour, then heated to 133°C and cured for 1.5 hours. It was then cooled to 55°C at a rate of 0.5°C / min and demolded. The cured package was placed in a 145°C oven for 3 hours and naturally cooled to room temperature to obtain the chip inductor packaging material.

[0045] Example 2:

[0046] (1) 50 g of hollow glass microspheres (average particle size of 20 μm) were added to a mixed solvent of 300 g of anhydrous ethanol and 700 g of deionized water, ultrasonicated for 30 min, and then 5 g of γ-aminopropyltrimethoxysilane was added. The temperature was raised to 55°C, stirred for 6 h, centrifuged, washed with deionized water and anhydrous ethanol three times each, and vacuum dried to obtain amino-modified hollow glass microspheres.

[0047] (2) 50 g of aminated hollow glass microspheres were added to 206 g of diethylenetriamine, ultrasonically treated for 30 min, and then 34 g of methyl acrylate and 500 g of methanol were added. The mixture was stirred and reacted at room temperature for 6 h. The methanol was then removed by heating to 150 ° C. and stirred and reacted for 24 h. The mixture was centrifuged, washed with N, N-dimethylacetamide three times, and vacuum dried to obtain branched polyamidoamine grafted hollow glass microspheres.

[0048] (3) 50 g of branched polyamide-grafted hollow glass microspheres were added to 5000 g of deionized water, ultrasonically treated for 30 min, and then 92.8 g of boric acid and 63 g of melamine were added. The temperature was raised to 95 ° C. and stirred for 8 h. The mixture was naturally cooled to room temperature, filtered, and vacuum dried to obtain melamine borate-modified hollow glass microspheres.

[0049] (4) The melamine borate-modified hollow glass microspheres were transferred to a tube furnace, heated to 1100°C at a rate of 10°C / min under a nitrogen atmosphere and kept at that temperature for 4 h, then cooled to 500°C at a rate of 10°C / min, and finally cooled naturally to room temperature to obtain boron nitride-modified hollow glass microspheres;

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

[0051] (6) The adhesive was 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 the injection was completed, it was cured at 80°C for 1.5 hours, then heated to 135°C and cured for 2 hours. It was then cooled to 60°C at a rate of 1°C / min and demolded. The cured package was placed in a 150°C oven for 4 hours and naturally cooled to room temperature to obtain the chip inductor packaging material.

[0052] Example 3:

[0053] (1) 50 g of hollow glass microspheres (average particle size of 20 μm) were added to a mixed solvent of 300 g of anhydrous ethanol and 700 g of deionized water, ultrasonicated for 40 min, and then 10 g of γ-aminopropyltrimethoxysilane was added. The temperature was raised to 57 ° C. and stirred for 7 h. The mixture was centrifuged and washed with deionized water and anhydrous ethanol three times each. The mixture was vacuum dried to obtain amino-modified hollow glass microspheres.

[0054] (2) 50 g of aminated hollow glass microspheres were added to 288 g of diethylenetriamine, ultrasonically treated for 30 min, and then 51 g of methyl acrylate and 800 g of methanol were added. The mixture was stirred and reacted at room temperature for 7 h. The methanol was then removed by heating to 152 ° C. The mixture was stirred and reacted for 28 h. The mixture was centrifuged, washed with N, N-dimethylacetamide three times, and vacuum dried to obtain branched polyamidoamine grafted hollow glass microspheres.

[0055] (3) 50 g of branched polyamide amine grafted hollow glass microspheres were added to 6000 g of deionized water, ultrasonically treated for 40 min, and then 110 g of boric acid and 82 g of melamine were added. The temperature was raised to 97 ° C. and stirred for 9 h. The mixture was naturally cooled to room temperature, filtered, and vacuum dried to obtain melamine borate modified hollow glass microspheres.

[0056] (4) The melamine borate modified hollow glass microspheres were transferred to a tube furnace, heated to 1150°C at a rate of 12°C / min under a nitrogen atmosphere and kept at this temperature for 4.5 h, then cooled to 550°C at a rate of 12°C / min, and finally cooled naturally to room temperature to obtain boron nitride modified hollow glass microspheres;

[0057] (5) 120 g of epoxy resin E-51 was dehydrated at 90 ° C for 2 h, then transferred to a vacuum stirring kettle, and then 20 g of γ-glycidyloxypropyltrimethoxysilane and 1.8 g of defoamer BYK-066N were added, and stirred at a speed of 600 rpm for 40 min. Then, 80 g of boron nitride modified hollow glass microspheres and 200 g of spherical silica powder (average particle size 1 μm) were added, and stirred at a speed of 1000 rpm for 25 min. Then, 40 g of anhydride curing agent methyltetrahydrophthalic anhydride and 1 g of accelerator 2-ethyl-4-methylimidazole were added, and stirred at a speed of 250 rpm for 8 min. Finally, the mixture was kept at a vacuum degree of -0.095 MPa for 30-50 min to obtain a rubber compound;

[0058] (6) The adhesive was 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 the injection was completed, it was cured at 82°C for 2 h, then heated to 137°C and cured for 2.5 h. It was then cooled to 65°C at a rate of 2°C / min and demolded. The cured package was placed in a 155°C oven for 5 h and naturally cooled 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 by amino-treated hollow glass microspheres;

[0061] The specific steps are as follows:

[0062] (1) 50 g of hollow glass microspheres (average particle size of 20 μm) were added to a mixed solvent of 300 g of anhydrous ethanol and 700 g of deionized water, ultrasonicated for 30 min, and then 5 g of γ-aminopropyltrimethoxysilane was added. The temperature was raised to 55°C, stirred for 6 h, centrifuged, washed with deionized water and anhydrous ethanol three times each, and vacuum dried to obtain amino-modified hollow glass microspheres.

[0063] (2) 50 g of aminated hollow glass microspheres were added to 5000 g of deionized water, ultrasonically treated for 30 min, and then 92.8 g of boric acid and 63 g of melamine were added. The temperature was raised to 95 ° C. and stirred for 8 h. The mixture was naturally cooled to room temperature, filtered, and vacuum dried to obtain melamine borate-modified hollow glass microspheres.

[0064] (3) The melamine borate-modified hollow glass microspheres were transferred to a tube furnace, heated to 1100°C at a rate of 10°C / min under a nitrogen atmosphere and kept at that temperature for 4 h, then cooled to 500°C at a rate of 10°C / min, and finally cooled naturally to room temperature to obtain boron nitride-modified hollow glass microspheres;

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

[0066] (5) The adhesive was 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 the injection was completed, it was cured at 80°C for 1.5 h, then heated to 135°C and cured for 2 h. It was then cooled to 60°C at a rate of 1°C / min and demolded. The cured package was placed in a 150°C oven for 4 h and naturally cooled to room temperature to obtain the packaging material.

[0067] Comparative Example 2:

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

[0069] The specific steps are as follows:

[0070] (1) 50 g of hollow glass microspheres (average particle size of 20 μm) were added to 5000 g of deionized water, ultrasonically treated for 30 min, and then 92.8 g of boric acid and 63 g of melamine were added. The mixture was heated to 95 ° C. and stirred for 8 h. The mixture was naturally cooled to room temperature, filtered, and vacuum dried to obtain melamine borate-modified hollow glass microspheres.

[0071] (2) The melamine borate-modified hollow glass microspheres were transferred to a tube furnace, heated to 1100°C at a rate of 10°C / min under a nitrogen atmosphere and kept at that temperature for 4 h, then cooled to 500°C at a rate of 10°C / min, and finally cooled naturally to room temperature to obtain boron nitride-modified hollow glass microspheres;

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

[0073] (4) The adhesive was 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 the injection was completed, it was cured at 80°C for 1.5 hours, then heated to 135°C and cured for 2 hours. It was then cooled to 60°C at a rate of 1°C / min and demolded. The cured package was placed in a 150°C oven for 4 hours and naturally cooled to room temperature to obtain the packaging 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) 100 g of epoxy resin E-51 was dehydrated at 85 ° C for 1.5 h, then transferred to a vacuum stirring kettle, 15 g of γ-glycidyloxypropyltrimethoxysilane and 1.2 g of defoamer BYK-066N were added, and stirred at a speed of 500 rpm for 30 min. Then, 60 g of hollow glass microspheres (average particle size of 20 μm) and 140 g of spherical silica powder (average particle size of 1 μm) were added, and stirred at a speed of 800 rpm for 20 min. Then, 30 g of anhydride curing agent methyltetrahydrophthalic anhydride and 0.8 g of accelerator 2-ethyl-4-methylimidazole were added, and stirred at a speed of 200 rpm for 5 min. Finally, the mixture was kept at a vacuum degree of -0.095 MPa for 40 min to obtain a rubber compound;

[0078] (2) The adhesive was 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 the injection was completed, it was cured at 80°C for 1.5 hours, then heated to 135°C and cured for 2 hours. It was then cooled to 60°C at a rate of 1°C / min and demolded. The cured package was placed in a 150°C oven for 4 hours and naturally cooled to room temperature to obtain the packaging 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 92.8 g of boric acid and 63 g of melamine to 5000 g of deionized water, heat to 95° C., stir for 8 h, cool naturally to room temperature, filter, and vacuum dry to obtain melamine borate;

[0083] (2) transferring the melamine borate to a tube furnace, heating it to 1100°C at a rate of 10°C / min under a nitrogen atmosphere and holding it for 4 h, then cooling it to 500°C at a rate of 10°C / min, and finally cooling it naturally to room temperature to obtain boron nitride;

[0084] (3) 100 g of epoxy resin E-51 was dehydrated at 85 ° C for 1.5 h, then transferred to a vacuum stirring kettle, 15 g of γ-glycidyloxypropyltrimethoxysilane and 1.2 g of defoamer BYK-066N were added, and stirred at 500 rpm for 30 min. Then, 60 g of boron nitride and 140 g of spherical silicon powder (average particle size 1 μm) were added, and stirred at 800 rpm for 20 min. Then, 30 g of anhydride curing agent methyltetrahydrophthalic anhydride and 0.8 g of accelerator 2-ethyl-4-methylimidazole were added, and stirred at 200 rpm for 5 min. Finally, the mixture was kept at a vacuum degree of -0.095 MPa for 40 min to obtain a rubber compound;

[0085] (4) The adhesive was 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 the injection was completed, it was cured at 80°C for 1.5 hours, then heated to 135°C and cured for 2 hours. It was then cooled to 60°C at a rate of 1°C / min and demolded. The cured package was placed in a 150°C oven for 4 hours and naturally cooled to room temperature to obtain the packaging material.

[0086] Performance testing:

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

[0088] Mechanical strength test: With reference to GB / T 9341-2008, a microcomputer-controlled electronic universal testing machine was used in a three-point bending mode with a span of 64 mm and a loading rate of 2 mm / min. The maximum load at fracture of the specimen was recorded and the flexural 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. A constant pressure of 0.5 N was applied to ensure uniform contact between the electrodes. The scanning mode was selected as single-frequency test, the frequency was set to 1.000 MHz, and the measurement mode was Cp-D. After stabilization, the capacitance value was read and the dielectric constant was calculated. 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 of Example 2 in Table 1, the chip inductor packaging material prepared by the present invention exhibits an excellent balance of comprehensive properties, which may be attributed to the unique structural advantages brought about by the in-situ generation mechanism of boron nitride on the surface of branched polyamidoamine modified microbeads. The abundant amino functional groups in the branched polyamidoamine molecular chain may provide uniformly distributed nucleation sites for the melamine borate precursor, guiding the orderly growth of boron nitride crystals during the high-temperature nitridation process, forming a surface-modified layer with good crystallinity and morphology control. This in-situ generated boron nitride layer may establish a strong chemical bond 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 polyamidoamine 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] The data from Example 2 and Comparative Example 1 in Table 1 demonstrate that branched polyamidoamine grafting significantly improves all performance indicators compared to simple amination. This demonstrates that the molecular structure design of branched polyamidoamine plays a crucial role in optimizing the formation and dispersion of boron nitride. Comparative Example 1, using only amination-modified hollow glass microspheres, may have a relatively limited density and spatial distribution of surface amino functional groups. This lacks sufficient reactive sites for interaction with the melamine borate precursor, resulting in uneven nucleation density for the boron nitride and potential problems such as inconsistent thickness and structural defects in the resulting modified layer.

[0095] The data from Example 2 and Comparative Example 2 in Table 1 demonstrate that dual surface modification with amination and branched polyamidoamine plays a key role in improving performance compared to unmodified treatments. This stepwise functionalization strategy likely creates ideal conditions for the effective generation and structural control of boron nitride. Comparative Example 2 directly utilizes pristine hollow glass microspheres, whose surfaces lack organic functional groups and reactive sites. The melamine borate precursor adheres primarily to the microsphere surface via physical adsorption. This weak interaction can lead to uneven precursor distribution, making desorption and aggregation more likely during the subsequent high-temperature nitridation process, compromising the continuity and stability of the modified boron nitride layer.

[0096] From the data of Example 2 and Comparative Example 3 in Table 1, it can be seen that 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 position of boron nitride as a thermal conductive functional component in the composite material. Comparative Example 3 uses hollow glass microspheres that have not been modified with boron nitride. The thermal conductivity of the material mainly depends on the thermal conductivity of the glass substrate itself, and the inherent low thermal conductivity of the glass material limits the thermal conductivity performance of the overall composite material. Although the hollow structure is conducive to reducing the weight of the material, it also further reduces the effective thermal conductivity cross-sectional area, resulting in low heat transfer efficiency. The boron nitride modification layer generated in situ in Example 2 may have constructed a continuous high thermal conductivity channel on the surface of the microspheres. The hexagonal lattice structure and strong covalent bond characteristics of boron nitride give it excellent phonon transmission ability, which can effectively improve the heat transfer efficiency on the surface of the filler particles. A good interface bonding may be formed between the in situ generated boron nitride and the glass substrate, reducing the influence of the interfacial thermal resistance, so that heat can be smoothly transferred in the filler network. At the same time, 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, thereby achieving synergistic optimization of thermal conductivity and mechanical strength.

[0097] As can be seen from the data of Example 2 and Comparative Example 4 in Table 1, boron nitride-modified hollow glass microspheres show obvious technical advantages in terms of comprehensive performance optimization compared to the addition of boron nitride powder alone, especially in terms of the balance control of mechanical strength and dielectric properties. Although Comparative Example 4 performs well in thermal conductivity, the significant decrease in mechanical strength and the significant increase in dielectric constant indicate that the independent boron nitride filler has dispersibility and interface compatibility problems. Boron nitride powder, as an independent filler component, may form local agglomeration and stress concentration phenomena in the composite matrix. These structural defects not only affect the uniform transmission of stress, but also may produce polarization effects under the action of an electric field, leading to increased dielectric loss. In contrast, the boron nitride in Example 2 forms an integrated composite filler structure with hollow glass microspheres through an in-situ generation method, which may achieve a more uniform dispersion state and optimized interface properties. The in-situ generated boron nitride modified layer not only maintains good thermal conductivity, but also enhances the structural integrity and interface stability of the filler through chemical bonding with the glass substrate and molecular bridging of the branched polyamide amine. This design may effectively avoid the agglomeration problems and interface defects caused by the addition of boron nitride powder, while maintaining high mechanical strength and low dielectric constant while achieving excellent thermal conductivity, 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 illustrative and is not intended to imply that the scope of the present invention is limited to these examples. Within the scope of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

Claims

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

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 the melamine, boric acid and branched polyamidoamine grafted hollow glass microspheres is 44-82:75-110:

50.

4. The chip inductor packaging material according to claim 1, characterized in that: The preparation method of the branched polyamide amine grafted hollow glass microspheres comprises the following steps: (1) Using γ-aminopropyltrimethoxysilane to graft hollow glass microspheres to obtain amino-modified hollow glass microspheres; (2) Diethylenetriamine and methyl acrylate are grafted and cross-linked 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 the step (1), the weight ratio of γ-aminopropyltrimethoxysilane to hollow glass microspheres is 1-10:50; and in the step (2), the weight ratio of diethylenetriamine, methyl acrylate and amino 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 gamma-glycidyloxypropyltrimethoxysilane, 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 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 defoaming agent is one of BYK-066N, BYK-A530 and TEGO Foamex 810 or a mixture of several thereof.

10. A method for preparing a chip inductor packaging material according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1: Dehydrate the epoxy resin, add a silane coupling agent and a defoamer BYK-066N, stir, add boron nitride-modified hollow glass microspheres and spherical silica powder, stir, add a curing agent and an accelerator, stir, and vacuum degas to obtain a rubber compound; S2: pouring the glue into the chip inductor mold. After the pouring is completed, heat curing, demoulding, heat treatment, and natural cooling to room temperature are performed to obtain the chip inductor packaging material.