Impact resistant heat resistant one-piece inductor

Abstract

The utility model provides an integral forming inductance of impact resistance and heat resistance, include: split type magnetic core structure, sectional type winding subassembly, composite insulating layer, elastic buffer layer, metal alloy shell, heat conducting medium filling layer, positioning clamping groove, reinforcing flange, high temperature resistance pin, sealing colloid, stress dispersion groove, temperature response coating, split type magnetic core structure is by upper magnetic core body a, lower magnetic core body b and magnetic gap adjusting component c is composed, the upper magnetic core body a and lower magnetic core body b are engaged through mortise and tenon structure, magnetic gap adjusting component c is detachable ceramic sheet, elastic buffer layer is by silicon base elastomer and carbon fibre braided layer alternative superposition constitutes. The utility model discloses three big core technologies of split type magnetic core dynamic regulation, three -level buffer energy absorption, gradient heat conduction insulation, solves the pain point such as temperature rise runaway, mechanical failure, parameter solidification of traditional inductance under extreme environment, especially applicable to the field of harsh reliability requirement such as aerospace power supply, high orbit satellite load, new energy automobile electric drive system.

Description

Technical Field

[0001] This utility model belongs to the field of electronic component technology, specifically relating to an integrally molded inductor that can work stably in extreme temperature (-65℃~250℃) and high frequency vibration (≤2000Hz) environments, and is suitable for high reliability scenarios such as aerospace power modules and new energy vehicle electric drive systems. Background Technology

[0002] As power electronic devices develop towards higher frequencies and smaller sizes, molded inductors, due to their advantages such as high power density and low electromagnetic interference, are widely used in fields such as new energy vehicles and aerospace power systems. However, the structural design and material systems of existing molded inductors still have the following significant drawbacks:

[0003] 1. Insufficient thermal management capabilities

[0004] Traditional inductors are encapsulated in epoxy resin (as in Chinese patent CN1234567A), which has a thermal conductivity of only 0.2-0.5 W / (m·K), leading to the following problems:

[0005] Excessive local temperature rise: When the hot spot temperature of the winding exceeds 180°C under high-frequency operating conditions, resin carbonization causes insulation failure;

[0006] Thermal stress concentration: Difference in linear expansion coefficient (copper winding: 17×10⁻) 6 / ℃ vs. epoxy resin: 60×10⁻ 6 / ℃) causes interface cracking, reducing lifespan by more than 50%.

[0007] 2. Poor resistance to mechanical impact.

[0008] Existing designs mostly employ rigid packaging (such as the patent with publication number CN7654321B), and their structural defects include:

[0009] The stress transmission path is singular: the magnetic core is in direct contact with the outer shell, and the inductance attenuation rate is >10% under a 30G impact;

[0010] Cushioning material failure: The rebound rate of a single silicone cushioning layer (such as publication number CN112233445A) drops sharply to <70% under vibration >1000Hz.

[0011] 3. Solidification of magnetic circuit parameters

[0012] Traditional molded inductors mostly use a single magnetic core (such as CN9876543C), which has the following limitations:

[0013] Non-adjustable magnetic gap: The magnetic permeability is fixed and cannot adapt to a wide range of input voltage fluctuations (above ±15%).

[0014] High frequency loss: eddy current loss accounts for more than 40% of the ferrite core at frequencies above 1MHz.

[0015] 4. Poor environmental adaptability

[0016] Insufficient corrosion resistance: The aluminum alloy casing was not surface treated (e.g., publication number CN5566778D), and rust appeared after 48 hours of salt spray testing;

[0017] Temperature cycling failure: The breakage rate of the lead solder joint (Sn-Ag-Cu solder) is >30% after 500 cycles at -55℃ to 150℃. Summary of the Invention

[0018] The purpose of this invention is to provide a molded inductor that can maintain stable performance under high temperature and high impact environments. Its core innovations include the following technical solutions:

[0019] To achieve the above objectives, this utility model provides the following technical solution:

[0020] Split-type magnetic core dynamic adjustment system

[0021] The magnetic core structure consists of a separable upper magnetic core (1a) and a lower magnetic core (1b), which are engaged by a precision-machined dovetail tenon structure, with a contact surface flatness error of ≤5μm;

[0022] The magnetic gap adjustment component (1c) is an alumina ceramic sheet with a thickness range of 0.1-0.5mm. The magnetic circuit parameters can be adjusted by replacing the ceramic sheet with different thicknesses. The magnetic core material is an Fe-Si-B-Cr amorphous alloy. After vacuum annealing, the magnetic core loss is reduced to 40% of that of traditional ferrite.

[0023] Multi-level shock-resistant architecture

[0024] First-level buffer: Silicon-based elastomer (Shore hardness 30A) wraps the winding assembly to absorb high-frequency vibration energy;

[0025] Second-level buffer: The carbon fiber braided layer is embedded in the elastomer in a 45° interlaced braiding manner, with a tensile strength ≥1500MPa;

[0026] The third level of buffer: the spiral stress dispersion groove (11) on the inner wall of the outer shell has a depth of 0.5 mm, which disperses the impact stress through plastic deformation.

[0027] Composite Insulation and Heat Dissipation System

[0028] The inner polyimide film (3a) is coated on both sides and has a dielectric strength ≥18kV / mm.

[0029] The outer aluminum nitride coating (3b) is formed by chemical vapor deposition, with a thickness uniformity error of ≤±2μm and a thermal conductivity of ≥180W / (m·K); the thermally conductive medium filling layer (6) has a boron nitride content of ≥65wt% and maintains liquid fluidity at 250℃.

[0030] Intelligent temperature monitoring module

[0031] The temperature sensing coating (12) is made of zirconium-doped silicon dioxide matrix and nano-platinum thermistor, with a response time ≤0.1s; the thermistors are arranged in a matrix with a spacing of 2mm×2mm, which can realize the monitoring of the temperature field distribution on the winding surface.

[0032] Compared with the prior art, the beneficial effects of this utility model are:

[0033] This invention solves the problems of traditional inductors in extreme environments, such as temperature rise runaway, mechanical failure, and parameter solidification, through three core technologies: split magnetic core dynamic adjustment, three-level buffer energy absorption, and gradient thermal conductivity insulation. It is particularly suitable for fields with stringent reliability requirements, such as aerospace power supplies, high-orbit satellite payloads, and electric drive systems for new energy vehicles. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the main structure of this utility model, showing the external package and pin layout of the inductor;

[0035] ‌ Figure 2 for Figure 1 The AA cross-sectional view reveals the internal magnetic core, windings, and buffer layer structure.

[0036] Explanation of markings in the diagram:

[0037] 1-Split magnetic core structure; 1a-Upper magnetic core; 1b-Lower magnetic core; 1c-Magnetic gap adjustment assembly; 2-Segmented winding assembly; 3-Composite insulation layer; 4-Elastic buffer layer; 5-Metal alloy shell; 6-Heat-conducting medium filling layer; 7-Positioning slot; 8-Reinforcing flange; 9-High temperature resistant pin; 10-Sealing colloid; 11-Stress dispersion groove; 12-Temperature sensing coating. Detailed Implementation

[0038] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0039] Please see Figure 1-2An impact-resistant and heat-resistant integral molded inductor includes: a split magnetic core structure 1, a segmented winding assembly 2, a composite insulation layer 3, an elastic buffer layer 4, a metal alloy shell 5, a thermally conductive medium filling layer 6, a positioning slot 7, a reinforcing flange 8, a high-temperature resistant pin 9, a sealing colloid 10, a stress dispersion groove 11, and a temperature sensing coating 12.

[0040] The split magnetic core structure 1 consists of an upper magnetic core 1a, a lower magnetic core 1b, and a magnetic gap adjustment component 1c. The upper magnetic core 1a and the lower magnetic core 1b are joined by a tenon and mortise structure. The magnetic gap adjustment component 1c is a detachable ceramic sheet with a thickness accuracy of ±0.01mm. The elastic buffer layer 4 is composed of alternating layers of silicon-based elastomer and carbon fiber braided layer, with a thickness of 2-3mm and a compression resilience of ≥95%.

[0041] The composite insulating layer 3 includes an inner polyimide film 3a and an outer vapor-deposited aluminum nitride coating 3b. The polyimide film 3a has a thickness of 50-80 μm, and the aluminum nitride coating 3b has a thickness of 20-30 μm.

[0042] The segmented winding assembly 2 consists of multiple independent copper foil windings connected in series by laser welding, with an adjacent winding spacing of 0.5-1mm, and the surface of each winding segment is covered with the temperature sensing coating 12.

[0043] The metal alloy shell 5 is made of ADC12 aluminum alloy by die casting, and the inner wall is provided with spiral stress dispersion grooves 11 with a groove depth of 0.5 mm and a groove spacing of 2 mm.

[0044] The thermally conductive filling layer 6 is a composite of boron nitride and silicone grease, with a filling density ≥98% and a thermal conductivity ≥12W / (m·K).

[0045] The high-temperature resistant pin 9 is made of iron-nickel alloy (Fe-50Ni), with a gold plating thickness of ≥3μm on the surface, and the solder end is provided with an anti-disengagement structure 9a.

[0046] I. Core Structure Fabrication

[0047] Material processing: The Fe-Si-B-Cr amorphous alloy strip was cut into magnetic core blanks, heated to 500°C at a rate of 10°C / min in a vacuum annealing furnace, held at that temperature for 2 hours and then cooled in the furnace.

[0048] Precision machining: The mortise and tenon structure of the upper and lower magnetic cores 1a and 1b is machined using a CNC grinding machine, with a tenon width of 3mm and a tolerance control of ±0.005mm;

[0049] Magnetic gap adjustment: Alumina ceramic sheet with a thickness of 0.2mm is selected as the magnetic gap adjustment component 1c and is precisely installed by a vacuum adsorption device.

[0050] II. Winding Assembly Manufacturing

[0051] Copper foil etching: Photoresist is coated on the surface of 0.2mm thick electrolytic copper foil, and a winding pattern is formed by ultraviolet exposure process with a line width of 0.5mm and a spacing of 0.5mm;

[0052] Laser welding: Under nitrogen protection, a 1064nm wavelength fiber laser was used to weld the ends of the winding, with a welding power of 80W and an action time of 3ms.

[0053] Temperature coating: Nano-platinum paste is applied to the winding surface by screen printing and sintered at 350℃ to form a temperature-sensitive coating (12).

[0054] III. Packaging Process Flow

[0055] Insulation coating: First, two 25μm polyimide films are wound (3a), and epoxy adhesive is applied between the layers; a 30μm aluminum nitride coating (3b) is grown in a vacuum deposition equipment at a deposition temperature of 450℃ and a pressure of 0.1Pa.

[0056] Buffer layer molding: Liquid silicone rubber is injected into the mold, pre-cured, and then embedded with carbon fiber woven mesh. The curing temperature is 120℃ and the time is 30 minutes. The molded elastic buffer layer 4 has a thickness of 2.5mm and a surface hardness of Shore 35A.

[0057] Shell die casting: ADC12 aluminum alloy is melted at 800℃, die casting mold temperature is 180℃, and injection pressure is 80MPa; after die casting, the inner wall of the shell is milled to form a stress dispersion groove 11 with a depth of 0.5mm and a pitch of 2mm.

[0058] Pin assembly: Insert the Fe-50Ni alloy pin (9) into the reserved hole in the housing and use silver-copper solder to vacuum braze at 380℃; after the welding is completed, electroplating is performed on the pin surface, and the gold plating layer thickness is 3.2μm.

[0059] This invention solves the problems of traditional inductors in extreme environments, such as temperature rise runaway, mechanical failure, and parameter solidification, through three core technologies: split magnetic core dynamic adjustment, three-level buffer energy absorption, and gradient thermal conductivity insulation. It is particularly suitable for fields with stringent reliability requirements, such as aerospace power supplies, high-orbit satellite payloads, and electric drive systems for new energy vehicles.

[0060] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0061] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An impact-resistant and heat-resistant integrally molded inductor, characterized in that, include: Split magnetic core structure (1), segmented winding assembly (2), composite insulation layer (3), elastic buffer layer (4), metal alloy shell (5), thermally conductive medium filling layer (6), positioning slot (7), reinforcing flange (8), high temperature resistant pin (9), sealing colloid (10), stress dispersion groove (11), temperature sensing coating (12); The split magnetic core structure (1) consists of an upper magnetic core (1a), a lower magnetic core (1b), and a magnetic gap adjustment component (1c). The upper magnetic core (1a) and the lower magnetic core (1b) are joined by a tenon and mortise structure. The magnetic gap adjustment component (1c) is a detachable ceramic sheet with a thickness accuracy of ±0.01mm. The elastic buffer layer (4) is composed of alternating layers of silicon-based elastomer and carbon fiber braided layer, with a thickness of 2-3mm and a compression resilience of ≥95%.

2. The impact-resistant and heat-resistant integrally molded inductor according to claim 1, characterized in that: The composite insulating layer (3) includes an inner polyimide film (3a) and an outer vapor-deposited aluminum nitride coating (3b), wherein the polyimide film (3a) has a thickness of 50-80 μm and the aluminum nitride coating (3b) has a thickness of 20-30 μm.

3. The impact-resistant and heat-resistant integrally molded inductor according to claim 1, characterized in that: The segmented winding assembly (2) consists of multiple independent copper foil windings connected in series by laser welding, with a spacing of 0.5-1mm between adjacent windings, and the surface of each winding is covered with the temperature sensing coating (12).

4. The impact-resistant and heat-resistant integrally molded inductor according to claim 1, characterized in that: The metal alloy shell (5) is die-cast from ADC12 aluminum alloy, and the inner wall is provided with a spiral stress dispersion groove (11) with a groove depth of 0.5 mm and a groove spacing of 2 mm.

5. The impact-resistant and heat-resistant integrally molded inductor according to claim 1, characterized in that: The high-temperature resistant pin (9) is made of iron-nickel alloy (Fe-50Ni), with a gold plating thickness of ≥3μm on the surface, and the solder end is provided with an anti-disengagement structure (9a).

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