A T-Core preformed low-voltage thermo-pressed integral surface mount inductor

Abstract

This application relates to a T-Core preformed low-voltage hot-pressed integrally molded surface mount inductor, belonging to the field of electronic component technology. The inductor includes an independently preformed T-shaped magnetic core, a flat coil, and an integrally coated magnetic layer. The T-shaped magnetic core has a central limiting protrusion, and the flat coil is sleeved on the outside of the protrusion to achieve circumferential limiting. The integrally coated magnetic layer is coated onto the outside of the component using a secondary low-voltage hot-pressing process. The leads at both ends of the flat coil are bent downwards and attached to the bottom surface of the base, and then laser-stripped and electroplated to form an integrally molded surface mount electrode. The T-shaped magnetic core and the integrally coated magnetic layer combine to form a closed-loop, fully enclosed composite magnetic circuit structure. This application can effectively avoid coil damage and core porosity defects, eliminate the risk of electrode soldering defects, reduce high-frequency losses and electromagnetic interference, and improve product reliability and electrical performance.

Description

Technical Field

[0001] This application relates to the field of electronic components technology, specifically to a T-Core preformed low-voltage hot-pressed integrally molded surface mount inductor. Background Technology

[0002] Molded surface mount inductors, with their advantages of small size, good shielding, and high current carrying capacity, are widely used in high-frequency DC-DC power supplies, RF circuits, and high-power power supply circuits. Existing conventional molded surface mount inductors generally employ a one-time high-voltage cold-pressing process, combining coil and magnetic powder, and using a lead frame to spot-weld electrode structure. In this existing technology, the wound coil and alloy magnetic powder are directly mixed and placed into a mold, then pressed into the inductor body in one go using high-voltage equipment. Subsequently, the coil leads are connected to the lead frame and fixed by laser spot welding to form the external electrodes, and finally, the manufacturing process is completed through curing.

[0003] However, in the existing technology, due to problems such as coil damage caused by high-pressure cold pressing process, internal pore defects in magnetic core, insufficient reliability of spot welding electrode connection and poor magnetic circuit sealing, the product faces difficulties such as low yield, poor performance consistency and serious electromagnetic interference in miniaturized, high-reliability and high-frequency application scenarios. Summary of the Invention

[0004] This application provides a T-Core preformed low-voltage hot-pressed integral molded chip inductor, which can solve the technical problems of traditional integral molded chip inductors, such as easy damage to the coil during high-voltage cold pressing, unstable performance due to air holes in the magnetic core, easy electrode failure, and high high-frequency loss and severe electromagnetic interference due to poor magnetic circuit sealing.

[0005] To achieve the above objectives, this application provides the following technical solution: This application provides a T-Core pre-formed low-voltage hot-pressed integrally molded chip inductor, including an independently pre-formed T-shaped magnetic core, a flat coil, and an integrally coated magnetic layer. The T-shaped magnetic core is an integral structure formed by independent cold pressing and pre-baking curing. The T-shaped magnetic core includes a base and a central limiting protrusion integrally formed at the center of the base. The flat coil is sleeved and assembled on the outside of the central limiting protrusion. The central limiting protrusion is adapted to the inner hole of the flat coil to form a circumferential limiting and fixing of the flat coil. The integrally coated magnetic layer is coated and cured on the outside of the assembled T-shaped magnetic core and the flat coil using a secondary low-voltage hot pressing process. The two leads of the flat coil are bent vertically downward and attached to the bottom surface of the base. The integrally coated electrodes are formed by laser stripping and integral electroplating processes. The T-shaped magnetic core and the integrally coated magnetic layer combine to form a closed-loop fully enclosed composite magnetic circuit structure.

[0006] In one optional embodiment, the T-shaped magnetic core is individually pressed and pre-cured after being pre-treated with alloy magnetic powder, and then assembled with the flat coil after the shaping is completed.

[0007] In one optional embodiment, the integrally coated magnetic layer is formed by low-temperature and low-pressure hot pressing, and the magnetic powder is uniformly filled and coated on the outside of the T-shaped magnetic core and the flat coil. After forming, the magnetic layer has a dense structure without voids.

[0008] In one alternative embodiment, the integrated patch electrode is formed by directly bending and exposing the flat coil end for electroplating, thus eliminating the need for lead frame adapter structure and spot welding connection structure.

[0009] In one alternative embodiment, the outer diameter of the central limiting protrusion matches the inner diameter of the flat coil, and the flat coil is sleeved and fixed on the central limiting protrusion with a relatively fixed position.

[0010] In one optional embodiment, the fully enclosed composite magnetic circuit is formed by an inner solid T-shaped magnetic core and an outer dense integral covering magnetic layer to form an overall closed-loop magnetic circuit structure.

[0011] This application provides a T-Core preformed low-voltage hot-pressed integrated surface mount inductor. This solution constructs an independently preformed T-shaped magnetic core as the core support framework. The precise fit between the T-core's central limiting protrusion and the inner hole of the flat coil achieves rigid circumferential positioning and fixation of the coil, thus eliminating coil offset and extrusion deformation during subsequent processing. Based on this, a secondary low-voltage hot-pressing process uniformly and densely coats the integrated magnetic layer onto the outside of the component. The low-temperature, low-pressure environment allows the magnetic powder to fully fill and expel air, avoiding mechanical damage to the coil insulation layer from high-voltage stress and eliminating porosity and void defects inside the magnetic core, thereby significantly improving the magnetic permeability stability and anti-magnetic saturation capability of the magnetic core. Subsequently, by directly bending the leads at both ends of the flat coil vertically to the bottom surface of the base, and using laser stripping and overall electroplating processes, an integrated surface mount electrode is directly formed, eliminating the intermediate lead frame transfer and spot welding steps. This effectively shortens the conductive circuit and reduces contact resistance, completely eliminating the risk of poor soldering and desoldering. Finally, the inner solid T-core... The core and the dense outer magnetic coating together construct a closed-loop, fully enclosed composite magnetic circuit structure, which greatly limits the leakage of magnetic lines of force, thus effectively solving the problems of high high-frequency loss and severe electromagnetic interference caused by the unsealed magnetic circuit in traditional technologies. This technical solution achieves systematic optimization from structural constraints, molding process, electrode construction to magnetic circuit design, significantly improving the reliability and consistency of the device under harsh environments such as wide temperature range and vibration, while reducing DC resistance and high-frequency loss, meeting the urgent needs of high-density, high-frequency, and high-power applications for high-performance power inductors. Attached Figure Description

[0012] Figure 1 This application provides a schematic diagram of a T-Core preformed low-pressure hot-pressed integrally molded patch inductor structure. Detailed Implementation

[0013] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Equivalent structures and preparation schemes obtained by those skilled in the art based on these embodiments without creative effort are all within the protection scope of the present invention. Example 1

[0014] As shown in Figure 1, the T-Core pre-formed low-voltage hot-pressed integrated patch inductor of this invention is mainly composed of three core components: a T-shaped magnetic core 1, a flat coil 2, and an integrated magnetic coating layer 3. The T-shaped magnetic core is an independent integrated component, consisting of a base 11 and a central limiting protrusion 12. The base and the central limiting protrusion are integrally connected without any seams. The flat coil is a ring winding made of flat metal wire, with a through hole in the middle of the winding. The inner diameter of the through hole matches the outer diameter of the central limiting protrusion. The flat coil is directly sleeved on the outside of the central limiting protrusion from top to bottom, relying on the sidewall of the protrusion to form a radial constraint on the coil. Extended leads are reserved at both ends of the flat coil. The leads are bent vertically downwards and tightly attached to the lower surface area of ​​the base. By removing the surface magnetic material of the leads and then electroplating a metal coating, the patch electrode 21 is directly formed. This product does not have an independent metal lead frame, and there are no laser spot welding or resistance spot welding connection points between the coil and the electrode. The integrally wrapped magnetic layer completely encapsulates the entire outer area of ​​the T-shaped magnetic core and the flat coil. The inner wall of the magnetic layer is tightly attached to the outer wall of the T-shaped magnetic core. The inner T-shaped magnetic core and the outer integrally wrapped magnetic layer work together to form a complete closed magnetic flux circuit. Example 2

[0015] This invention utilizes a separate molding process to prepare the T-shaped magnetic core. After molding and constant-temperature curing, the magnetic powder first forms a rigid and complete magnetic core matrix. Once shaped, it is then assembled with a flat coil. The outer contour dimensions of the central limiting protrusion match the dimensions of the central through-hole of the flat coil. After assembly, the contact surfaces fit together, preventing the coil from sliding radially or rotating around its central axis. Throughout the subsequent hot-pressing process of the outer magnetic layer, the spatial position of the coil relative to the T-shaped magnetic core remains stable. Unlike traditional coil and magnetic powder mixed-pressing molding methods, this invention prefabricates a rigid magnetic core skeleton before assembling the coil, preventing the coil from being squeezed or displaced by flowing magnetic powder, resulting in higher assembly positioning accuracy. Example 3

[0016] The assembled magnetic core-coil assembly is placed into a molding mold, and magnetic powder is filled into the mold cavity. A low-temperature thermosetting process is then used to form an integrally coated magnetic layer. During the molding process, the magnetic powder can evenly fill all gaps around the assembly. The resulting integrally coated magnetic layer has no continuous voids or loose areas, and its overall structure is dense. It combines with the inner T-shaped magnetic core to form an integral composite magnet, free from defects such as breaks or air gaps. This layered molding method avoids the strong compressive stress caused by traditional one-time high-pressure processes, does not damage the surface insulation structure of the flat coil, and the dense magnetic layer improves the overall mechanical strength of the magnet. Example 4

[0017] The leads at both ends of the flat coil serve directly as the electrode substrate, eliminating the need for additional metal support adapters. After the leads are bent downwards and adhered to the bottom surface of the base, the magnetic material covering the lead surface is removed, exposing the internal conductive metal substrate. A solderable plating layer is then formed on the metal surface through an overall electroplating process, forming an integrated patch electrode. The entire electrode structure eliminates the need for two supporting processes: lead frame stamping and lead spot welding. The conductive path is formed solely by the flat coil body, eliminating multiple layers of transition contact interfaces. This reduces heat generation issues caused by contact resistance and eliminates the risk of solder joint detachment or poor soldering failure under long-term vibration and high / low temperature conditions. Example 5

[0018] The inner solid T-shaped magnetic core serves as the main magnetic flux transmission channel, while the outer dense, integrally coated magnetic core serves as the magnetic flux return channel. The two are seamlessly connected, forming a complete closed-loop magnetic circuit. Magnetic lines of force mainly circulate within the T-shaped magnetic core and the integrally coated magnetic layer, resulting in less outward leakage of magnetic flux. This leads to lower hysteresis and eddy current losses at high frequencies, less electromagnetic interference to surrounding PCB surface-mount components, and suitability for high-density circuit board integration applications. Example 6

[0019] The overall fabrication steps of the patch inductor of this invention are as follows: Step 1: Pre-treat the alloy magnetic powder, fill the treated powder into a special T-shaped mold for cold pressing, and then send it to a constant temperature environment for pre-baking and curing to obtain an independent T-shaped magnetic core with stable dimensions and rigid support capability; Step 2: Align the pre-wound flat coil with the central limiting protrusion and vertically downwards onto the upper surface of the base to complete the coil positioning assembly; Step 3: Place the assembled assembly into the molding mold, fill the mold with magnetic powder, and use a low-temperature hot pressing process to cure the powder, forming an integrally encapsulated magnetic layer that completely wraps the component; Step 4: Use a laser to remove the surface magnetic material at the lead position on the bottom surface of the base, completely exposing the coil metal leads, perform electroplating on the entire product, deposit a solderable metal layer on the exposed lead surface, form the patch electrode, and obtain the finished patch inductor after cleaning and inspection.

Claims

1. A T-Core preformed low-voltage thermo-pressed integrally molded chip inductor, comprising a flat coil (2) and an integrally coated magnetic layer (3), characterized in that, It also includes an independently prefabricated T-shaped magnetic core (1); the T-shaped magnetic core (1) is integrally formed with a base (11) and a central limiting protrusion (12), the flat coil (2) has a through hole in the middle, and the central limiting protrusion (12) passes through the through hole of the flat coil (2); the leads at both ends of the flat coil (2) are bent downwards and attached to the lower surface of the base (11) to form a patch electrode (21); the integrally covered magnetic layer (3) completely covers the T-shaped magnetic core (1) and the outer periphery of the flat coil (2), and the T-shaped magnetic core (1) and the integrally covered magnetic layer (3) are attached to each other to form a closed magnetic circuit.

2. The T-Core preformed low-voltage hot-pressed integrally molded surface mount inductor according to claim 1, characterized in that, The patch electrode (21) does not have an independent metal lead frame and spot welding connection part, but is composed of the exposed metal area after the flat coil (2) is bent.

3. The T-Core preformed low-voltage hot-pressed integrally molded surface mount inductor according to claim 1, characterized in that, The T-shaped magnetic core (1) is a separately pressed and solidified molded part. The flat coil (2) is sleeved and assembled on the central limiting protrusion (12) and then covered with an integral magnetic layer (3).

4. The T-Core preformed low-voltage hot-pressed integrally molded surface mount inductor according to claim 1, characterized in that, The integrated magnetic coating layer (3) has no through cavity inside and is combined with the T-shaped magnetic core (1) to form an integrated composite magnet.

5. A method for preparing the T-Core preformed low-voltage hot-pressed integrally molded chip inductor according to any one of claims 1 to 4, characterized in that, Includes the following steps: S1. The magnetic powder is molded and cured at a constant temperature to prepare an independent T-shaped magnetic core (1) with a base (11) and a central limiting protrusion (12). S2. The flat coil (2) is fitted through the central through hole onto the outside of the central limiting protrusion (12) of the T-shaped magnetic core (1); S3. Fill the outer periphery of the assembly of the T-shaped magnetic core (1) and the flat coil (2) with magnetic powder, and solidify it by low temperature hot pressing to form an integral magnetic coating layer (3). S4. Remove the surface magnetic material at the bottom lead position of the base (11), electroplat the exposed lead with a metal layer, and form a patch electrode (21).

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