PCB embedded inductor based on metal soft magnetic alloy material and application thereof

Abstract

This invention discloses a PCB-embedded inductor based on a soft magnetic alloy material and its application, relating to the field of inductor technology. Addressing the problems of core saturation and inductance decay in existing inductors under high current, this invention includes a printed circuit board (PCB) with a core made of a soft magnetic alloy material inside. Multiple turns of winding are routed through the core, forming a transverse flux inductance structure. This invention significantly improves the inductor's anti-saturation capability and inductance retention under high current by using a soft magnetic alloy material with high saturation flux density as the core in the PCB-embedded transverse flux structure. By comprehensively balancing loss and thermal resistance in the core area and thickness, optimal dimensional parameters are selected to significantly reduce thermal resistance while ensuring low inductance loss. Combined with the excellent thermal conductivity of the core material itself, the inductor also possesses excellent heat dissipation performance, effectively improving the heat dissipation problem of PCB-embedded structures.

Description

Technical Field

[0001] This invention relates to the field of inductor technology, and in particular to a PCB embedded inductor based on a soft magnetic alloy material and its application. Background Technology

[0002] With the rapid development of information and communication technologies and the widespread application of portable electronic devices, point-of-load converters (POL converters) play a crucial role in powering high-performance chips (such as CPUs and GPUs). According to Moore's Law, the number of transistors that can be placed within the same area of ​​an integrated circuit continues to increase with rapid technological iteration, leading to higher input current requirements for chips to meet their power demands. Correspondingly, POL converters powering these chips face significant challenges, needing to provide high output current while ensuring high conversion efficiency and fast transient response. Furthermore, considering the trend towards miniaturization and integration in portable electronic devices, POL converters typically also require low profile and high power density.

[0003] Currently, most commercial POL converters still use traditional discrete magnetic components that are bulky and have high profiles. These passive components reduce the space utilization of the converter and become a bottleneck for improving the power density of POL converters. To reduce size and increase power density, planar inductors and embedded inductors based on printed circuit boards (PCBs) have been widely used. These technologies effectively reduce the profile and improve space utilization by integrating magnetic components with active devices in three-dimensional space.

[0004] Existing technical solution: A co-fired ceramic (LTCC) substrate inductor for POL converters uses LTCC 40011 ferrite, a magnetic material with nonlinear permeability, to fabricate a planar inductor. Switches, resistors, capacitors, drivers, controllers, and other components are integrated on the inductor substrate, achieving 3D integration of active and passive devices, thereby increasing space utilization and achieving high power density. However, its topology is a single-phase buck converter (also known as a Buck converter), using an LTCC substrate to achieve high power density, with output current ranging from 2A to 15A and power density reaching 300W / in. 3 The disadvantages are that LTCC has a complex process and a long production cycle. When the inductor current increases, the magnetic core saturates and its inductance value decays rapidly, resulting in increased output voltage ripple, increased stress on the output capacitor and shortened lifespan. It also leads to increased inductor loss and reduced overall converter efficiency.

[0005] Therefore, there is an urgent need to develop a new type of inductor with high saturation flux density and high output current capability, as well as short production cycle, ease of manufacturing and good heat dissipation performance. Summary of the Invention

[0006] To address the aforementioned problems, this invention aims to provide a PCB-embedded inductor based on a soft magnetic alloy material. This inductor significantly improves its anti-saturation capability and inductance retention under high current by employing a soft magnetic alloy material with high saturation flux density as the core within a PCB-embedded lateral magnetic flux structure. Simultaneously, by comprehensively balancing loss and thermal resistance in the core area and thickness, optimal dimensional parameters are selected, significantly reducing thermal resistance while ensuring low inductance loss. Combined with the excellent thermal conductivity of the core material itself, the inductor also possesses superior heat dissipation performance, effectively improving the heat dissipation challenges of PCB-embedded structures.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: On the one hand, the present invention provides an application of a soft magnetic alloy material in the magnetic core of an embedded inductor in a PCB.

[0008] Furthermore, the dimensions of the PCB embedded inductor core are 12mm in length, 10mm in width, and 2mm in thickness.

[0009] Furthermore, the soft magnetic alloy material is selected from any one of iron-silicon-aluminum alloy, iron-silicon alloy, iron-silicon-aluminum-nickel alloy, or iron-silicon-molybdenum alloy.

[0010] On the other hand, the present invention provides a PCB embedded inductor based on a metal soft magnetic alloy material, comprising: a printed circuit board, and further comprising: The magnetic core, located inside the printed circuit board, is made of a soft magnetic alloy material. A multi-turn winding is disposed throughout the magnetic core, forming a transverse flux inductance structure together with the magnetic core.

[0011] Furthermore, the magnetic core is provided with: The central magnetic post is used to wind the multi-turn winding.

[0012] Furthermore, the multi-turn winding includes: Through-hole windings are arranged on both sides of the central magnetic post; A surface winding is disposed on the upper and lower surfaces of the via winding and is connected to the via winding.

[0013] Furthermore, this invention provides a method for fabricating a PCB embedded inductor based on a soft magnetic alloy material, the method comprising the following steps: The magnetic core is embedded in the inner layer of the printed circuit board; Through-hole windings are set on both sides of the central magnetic column; Surface windings are respectively provided on the upper and lower surfaces of the through-hole winding; The layers of a printed circuit board are pressed together to form a PCB embedded inductor.

[0014] In another aspect, the present invention provides a POL converter that includes the inductor as described above.

[0015] The beneficial effects of this invention are: (1) This invention selects a soft magnetic alloy material with high saturation magnetic flux density (such as DSH125 material) as the magnetic core, which together with a multi-turn winding forms a transverse flux inductor structure. Under the same magnetic core volume and number of turns, it can maintain a high effective permeability in the medium to high magnetic field range, thereby obtaining an inductance density higher than that of the existing LTCC 40011 ferrite. More importantly, the material has a low permeability decay rate under strong magnetic fields, which makes the inductance value of the inductor stable when the inductor is working at high current, and the anti-saturation performance is significantly improved. (2) The magnetic core material used in this invention has low hysteresis loss, and combined with its small size, further reduces the core loss. When the inductor of this invention is used in a POL converter, it can achieve higher conversion efficiency, especially under heavy load conditions. At the same time, the inductor is three-dimensionally integrated through a PCB embedded structure, which saves a lot of space and helps to improve the overall power density of the converter; (3) The inductor of the present invention has a small inductance value attenuation under high current. When applied to Buck converter, it can effectively suppress the influence of load change on filtering performance, thereby significantly improving the ripple quality of output current and voltage and reducing the requirements for output capacitor. This feature also enables the converter to have a higher output current capability, which can meet the increasing power requirements of portable electronic devices, data centers and other applications. (4) The present invention realizes the core embedding and winding integration based on mature PCB technology, with a short production cycle, suitable for mass manufacturing, and can significantly reduce the unit cost; (5) By optimizing dimensional parameters such as area and thickness, the magnetic core of the present invention achieves an optimal balance between inductance loss, thermal resistance, and inductance density while maintaining the target inductance value, significantly reducing thermal resistance while ensuring low inductance loss. In addition, the selected magnetic core material itself has low loss, low heat generation, and thermal conductivity much higher than that of traditional ferrite materials. These advantages combined give the inductor excellent thermal performance and effectively improve the heat dissipation problem of PCB embedded structures. Attached Figure Description

[0016] Figure 1 This is a three-dimensional exploded view of a PCB embedded inductor based on a soft magnetic alloy material proposed in this invention.

[0017] Figure 2 This is a schematic diagram of the magnetic core proposed in this invention.

[0018] Figure 3 These are three views of the magnetic core proposed in this invention.

[0019] Figure 4 This is a sample image of the magnetic core proposed in this invention.

[0020] Figure 5 This is a comparison diagram of the vertical flux inductor structure and the horizontal flux inductor structure proposed in this invention.

[0021] Figure 6 This is a schematic diagram of the winding structure of a single-turn winding proposed in this invention.

[0022] Figure 7 This is a schematic diagram of the winding structure of the three-turn winding proposed in this invention.

[0023] Figure 8 This is a diagram showing the magnetic field strength distribution of the three-turn transverse flux planar inductor proposed in this invention when a current of 20A passes through it.

[0024] Figure 9 This is the equivalent analysis model of the three-turn transverse magnetic flux planar inductor proposed in this invention.

[0025] Figure 10 This is a performance comparison chart of the present invention and the prior art under different winding turns.

[0026] Figure 11 This is a comparison chart showing the efficiency of the present invention and existing technologies when applied to POL converters.

[0027] Figure 12 This is a prototype model diagram of a converter based on the PCB embedded inductor proposed in this invention.

[0028] Figure 13 This is a physical image of a converter prototype based on the PCB embedded inductor proposed in this invention.

[0029] Figure 14 This is a power density comparison chart of the converter based on the PCB embedded inductor proposed in this invention and various converters based on traditional inductor schemes.

[0030] The above figures include the following reference numerals: 1. Printed circuit board; 2. Magnetic core; 21. Central magnetic column; 22. Through hole; 3. Multi-turn winding; 31. Through-hole winding; 32. Surface winding. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be further described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments, and not all of the embodiments.

[0032] In the description of this invention, it should be understood that the terms "front", "rear", "left", "right", "upper", "lower", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0033] Example 1: See attached document Figure 1 This application discloses a PCB embedded inductor based on a metal soft magnetic alloy material, comprising: a printed circuit board 1, wherein a magnetic core 2 is provided inside the printed circuit board 1, the magnetic core 2 is made of a metal soft magnetic alloy material with high saturation magnetic flux density; a multi-turn winding 3 is provided through the magnetic core 2, and the multi-turn winding 3 and the magnetic core 2 together constitute a transverse magnetic flux inductance structure.

[0034] Specifically, the printed circuit board 1 is made of ordinary PCB organic substrate, or it can be made of special substrates or processes such as direct copper-clad ceramic substrate (DBC) or direct copper-plated ceramic substrate (DPC) instead of ordinary PCB organic substrate.

[0035] Furthermore, the soft magnetic alloy material is selected from any one of iron-silicon-aluminum alloy, iron-silicon alloy, iron-silicon-aluminum-nickel alloy, or iron-silicon-molybdenum alloy. It not only possesses high saturation magnetic flux density but also has higher thermal conductivity than materials such as ferrites, exhibiting good thermal conductivity. For example, the material DSH125 has an initial permeability of only 125, but its relative permeability decreases very slowly with increasing magnetic field strength, meaning that its inductance value decreases very little with increasing inductor current. The magnetic core 2 in this embodiment uses DSH125 as its material.

[0036] Specifically, the magnetic core 2 is rectangular in shape, and has a central magnetic post 21. There is one central magnetic post 21, and through holes 22 are formed on both sides of the central magnetic post 21. The through holes 22 are circular and square in shape, as shown in the attached figure. Figure 2-4 As shown. It should be noted that the number of central magnetic pillars 21 can also be set to multiple, with almost no change in inductance performance, and the shape of the through hole 22 can also be any shape such as a perfect square, ellipse, or polygon.

[0037] In this embodiment, the design of the magnetic core 2 balances the relationship between dimensional parameters such as area and thickness and inductance loss, thermal resistance, and inductance density. To maintain a certain inductance value, the magnetic core 2 needs to increase its area while reducing its thickness. Although this process helps reduce thermal resistance, it may cause the inductance density efficiency to drop sharply after a certain point. To achieve the optimal balance between inductance loss, thermal resistance, and inductance density while maintaining the target inductance value, the optimal dimensional parameters were selected from the optimized dimensional range of the magnetic core after comprehensive consideration. That is, the overall dimensions of the magnetic core are set to 12mm in length, 10mm in width, and 2mm in thickness. Correspondingly, the width of the central magnetic post 21 is set to 3mm. While ensuring low inductance loss, the thermal resistance is significantly reduced. Combined with the characteristics of the selected material itself—low loss, low heat generation, and thermal conductivity much higher than that of traditional ferrite materials—the magnetic core 2 has excellent heat dissipation performance after being embedded in the printed circuit board 1, effectively alleviating the common problem of internal heat accumulation in PCB embedded structures.

[0038] Furthermore, as shown in the appendix Figure 5 As shown, existing planar inductor types include two types: vertical flux planar inductors and transverse flux planar inductors. Since transverse flux inductor structures can usually have higher inductance density, the present invention configures the multi-turn winding 3 based on the transverse flux inductor structure.

[0039] Specifically, the multi-turn winding 3 includes a through-hole winding 31 and a surface winding 32. The through-hole winding 31 is located within the through-hole 22, and the surface winding 32 is disposed on the upper and lower surfaces of the through-hole winding 31 and connected to it. Inductor current flows in from above the through-hole winding 31 on one side, passes through the lower surface winding 32, and flows out from the through-hole winding 31 on the other side, forming one turn of winding. This process is repeated through the upper surface winding 32, thus completing the winding of the multi-turn winding 3. (See attached diagram.) Figure 6 The attached diagram illustrates the winding structure of a single turn of the multi-turn winding 3. Figure 7 The diagram shows a schematic of the three-turn winding structure of the multi-turn winding 3.

[0040] More specifically, the via winding 31 can be prepared by any method such as filling the via with copper, silver, conductive glue, or conductive ink. The cross-section of the via winding 31 can be circular, square, or any polygonal. The material for preparing the surface winding 32 can be any material with good electrical conductivity, such as copper, iron, or aluminum.

[0041] The inductor fabrication method described in this embodiment is as follows: First, the magnetic core 2 is embedded in the inner layer of the printed circuit board 1; then, a via winding 31 is set in the through hole 22; then, surface windings 32 are set on the upper and lower surfaces of the via winding 31 respectively; finally, the layers of the printed circuit board 1 are pressed to form a PCB embedded inductor. A three-dimensional exploded view of the PCB embedded inductor is shown in the attached figure. Figure 1 As shown.

[0042] Example 2: This embodiment verifies the performance of the PCB embedded inductor described in Embodiment 1.

[0043] As attached Figure 8 The figure shows the magnetic field strength distribution of a three-turn transverse flux planar inductor when a current of 20A passes through it. As can be seen from the figure, the highest magnetic field strength exceeds 5000 A / m. However, the increase in magnetic field strength causes a decrease in the relative permeability of most soft magnetic materials, resulting in a rapid decay of the inductance value, which is detrimental to achieving high inductance density. This invention uses DSH125 material. Although the initial permeability of this material is only 125, its relative permeability decreases very slowly with increasing magnetic field strength. This means that as the inductor current increases, its inductance value decays very little. Combined with the transverse flux inductor structure of a PCB embedded inductor, a 3D integrated PCB embedded inductor with high saturation flux density is achieved.

[0044] Appendix Figure 9 An equivalent analytical model of a three-turn transverse flux planar inductor is presented, and its inductance density is calculated using the following formula: ; In the formula, Indicates the inductance value. Indicates the number of turns in the winding. Represents relative permeability. This represents the increment of the radius of the annulus. Indicates the thickness of the inductor. This indicates the spacing between two adjacent vias. This represents the radius of the circle in the equivalent analysis model (i.e., the integral change). Indicates the radius of the via. This indicates the actual width from the inductor via to the edge.

[0045] ; In the formula, This represents the volume of the inductor in the equivalent analysis model.

[0046] The inductance density is the result of dividing the inductance value by the inductor volume.

[0047] As attached Figure 10As shown, the inductance density of the PCB embedded inductor using DSH125 as the core material in this invention and the transverse flux planar inductor using LTCC 40011 ferrite as the core material in the prior art are compared under different winding turns. The curves show the changes. As can be seen from the figure, the inductance and inductance density of both materials increase with the increase of the number of winding turns. However, due to the increase in the number of winding turns, the magnetic field strength inside the core also increases. The PCB embedded inductor of this invention, due to its high saturation magnetic flux density, significantly maintains its inductance performance better, which is a significant advantage in terms of inductance density when used as a multi-turn planar inductor structure.

[0048] Example 3: This embodiment applies the PCB embedded inductor described in Embodiment 1 to a POL converter to further verify the performance of the PCB embedded inductor of the present invention.

[0049] The PCB embedded inductor described in this invention can be used in converters of any type of semiconductor switching device, such as silicon-based, gallium nitride-based, silicon carbide-based, or future gallium oxide-based. It can also be used as an inductor in a Buck converter, a resonant inductor in an LLC resonant converter, a resonant inductor in a resonant switched capacitor topology, or any converter topology that requires an inductor or can utilize an inductor for integration.

[0050] Because the PCB embedded inductor described in this invention has the characteristic of high saturation magnetic flux density, when applied to a Buck converter, the increase in inductor current caused by the increase in load current has little impact on the attenuation of its inductor performance, thus maintaining good inductor performance. This is beneficial to the good ripple quality of the Buck converter output, and this characteristic also improves the output current level of the Buck converter.

[0051] As attached Figure 11 The figure shows a comparison of the efficiency of the PCB embedded inductor using DSH125 as the core material in this invention and the transverse flux planar inductor using LTCC 40011 ferrite as the core material in the prior art when applied to a POL converter. (See attached figure.) Figure 10 and attached Figure 11 It is understood that the PCB embedded inductor using DSH125 in this invention can achieve higher inductance density, efficiency, and output current capability.

[0052] As attached Figure 12 The diagram shown is a prototype model of a converter based on the PCB embedded inductor described in this invention. The PCB embedded inductor is embedded in the PCB, and the overall dimensions of the converter prototype model are 16.5mm in length, 14mm in width, and 3mm in thickness. (See attached diagram.) Figure 13The image shown is a prototype of a converter based on the PCB-embedded inductor described in this invention. The PCB-embedded inductor is embedded in a PCB, and as can be seen from the image, the prototype's size is close to that of a coin. Due to its small overall size and thinness, the PCB-embedded inductor of this invention significantly reduces thermal resistance while maintaining low inductance loss. Simultaneously, the selected core material has high thermal conductivity and good thermal conductivity, giving the inductor excellent heat dissipation capabilities and overcoming the problem of heat dissipation being difficult within the PCB-embedded structure.

[0053] As attached Figure 14 The figure shows a power density comparison between the converter based on the PCB embedded inductor described in this invention and various converters based on traditional inductor solutions. As can be seen from the figure, the converter based on this invention can achieve both high output current capability and high power density.

[0054] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. Application of a soft magnetic alloy material in the core of a PCB embedded inductor.

2. The application according to claim 1, characterized in that: The dimensions of the PCB embedded inductor core are 12mm in length, 10mm in width, and 2mm in thickness.

3. The application according to claim 2, characterized in that: The soft magnetic alloy material is selected from any one of iron-silicon-aluminum alloy, iron-silicon alloy, iron-silicon-aluminum-nickel alloy, or iron-silicon-molybdenum alloy.

4. A PCB embedded inductor based on a soft magnetic alloy material, comprising: Printed circuit board (1), characterized in that it further includes: The magnetic core (2) is disposed inside the printed circuit board (1) and is made of a soft magnetic alloy material. A multi-turn winding (3) is disposed through the magnetic core (2) and together with the magnetic core (2) constitutes a transverse magnetic flux inductance structure.

5. A PCB embedded inductor based on a soft magnetic alloy material according to claim 4, characterized in that, The magnetic core (2) is provided with: The central magnetic column (21) is used to wind the multi-turn winding (3).

6. A PCB embedded inductor based on a soft magnetic alloy material according to claim 5, characterized in that, The multi-turn winding (3) includes: Through-hole windings (31) are arranged on both sides of the central magnetic post (21); A surface winding (32) is disposed on the upper and lower surfaces of the via winding (31) and connected to the via winding (31).

7. The method for fabricating a PCB embedded inductor based on a soft magnetic alloy material as described in claim 6, characterized in that, The method includes the following steps: The magnetic core (2) is embedded in the inner layer of the printed circuit board (1); Through-hole windings (31) are provided on both sides of the central magnetic column (21). Surface windings (32) are provided on the upper and lower surfaces of the through winding (31). The layers of the printed circuit board (1) are pressed to form a PCB embedded inductor.

8. A POL converter, characterized in that: The POL converter includes the inductor as described in any one of claims 4-6.

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