CN218676646U

CN218676646U - Circuit board integrated inductor and electronic equipment

Info

Publication number: CN218676646U
Application number: CN202221552068.7U
Authority: CN
Inventors: 陈奕君
Original assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Current assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Priority date: 2022-06-17
Filing date: 2022-06-17
Publication date: 2023-03-21
Anticipated expiration: 2032-06-17

Abstract

The application mainly relates to a circuit board integrated inductor and electronic equipment, wherein the circuit board integrated inductor comprises a substrate, a coil pattern, a dielectric layer and a magnetic film layer, the coil pattern is positioned on at least one side of the substrate, the dielectric layer covers the coil pattern, and the magnetic film layer is positioned on one side of the dielectric layer, which is far away from the substrate; the relative permeability of the magnetic film layer is greater than that of the medium layer, and the magnetic film layer is provided with a plurality of holes. The application provides a plurality of holes are seted up to circuit board integrated inductor on the magnetic film layer for the vortex in the magnetic film layer receives the hindrance of hole, thereby maintains the inductance under the unchangeable condition on a large scale at circuit board integrated inductor, reduces the eddy current loss.

Description

Circuit board integrated inductor and electronic equipment

Technical Field

The application relates to the technical field of electronic equipment, in particular to a circuit board integrated inductor and electronic equipment.

Background

With the trend of miniaturization and high density of electronic hardware, the surface area of the circuit board is reduced sharply, but the number of electronic components required to be mounted on the board is increased or decreased. The inductor is an indispensable component of electronic equipment, and most of the current inductors are firstly prepared into inductors and then are pasted on a circuit board, so that the area of the circuit board is occupied, the inductors need to be pasted separately, and the packaging efficiency is reduced.

Disclosure of Invention

The embodiment of the application provides a circuit board integrated inductor, which comprises a substrate, a coil pattern, a dielectric layer and a magnetic film layer, wherein the coil pattern is positioned on at least one side of the substrate; the relative permeability of the magnetic film layer is greater than that of the medium layer, and the magnetic film layer is provided with a plurality of holes.

The embodiment of the application provides electronic equipment, and the electronic equipment comprises the circuit board integrated inductor.

The beneficial effect of this application is: the application provides a plurality of holes are seted up to integrated inductance of circuit board on the magnetic film layer for the vortex in the magnetic film layer receives the hindrance of hole, thereby maintains the inductance at the integrated inductance of circuit board under the unchangeable condition on a large scale, reduces the eddy current loss.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the description below are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

Fig. 1 is a schematic disassembled structural diagram of an embodiment of an electronic device provided in the present application;

fig. 2 is a schematic structural diagram of an embodiment of the circuit board integrated inductor provided in the present application;

FIG. 3 is a schematic cross-sectional view of one embodiment of the integrated inductor of the circuit board of FIG. 2 taken along line III-III;

fig. 4 is a schematic structural diagram of an embodiment of the circuit board integrated inductor provided in the present application;

FIG. 5 is a schematic cross-sectional view of one embodiment of the integrated inductor of the circuit board of FIG. 4 taken along line V-V;

fig. 6 is a schematic flowchart of an embodiment of a method for manufacturing an integrated inductor of a circuit board according to the present application;

FIG. 7 is a schematic diagram of the integrated inductor of the circuit board of FIG. 6 at different steps in the manufacturing process;

fig. 8 is a schematic flowchart of an embodiment of a method for manufacturing an integrated inductor of a circuit board according to the present application;

fig. 9 is a schematic structural diagram of the integrated inductor of the circuit board shown in fig. 8 at different steps in the manufacturing process.

Detailed Description

The present application will be described in further detail with reference to the following drawings and examples. It is to be noted that the following examples are only illustrative of the present application, and do not limit the scope of the present application. Likewise, the following examples are only some examples and not all examples of the present application, and all other examples obtained by a person of ordinary skill in the art without any inventive work are within the scope of the present application.

Reference in the specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the specification. It is explicitly and implicitly understood by a person skilled in the art that the embodiments described herein can be combined with other embodiments.

Referring to fig. 1 to 5 together, fig. 1 is a schematic disassembled structure diagram of an embodiment of an electronic device provided in the present application, fig. 2 is a schematic structural diagram of an embodiment of a circuit board integrated inductor provided in the present application, fig. 3 is a schematic cross-sectional structure diagram of an embodiment of the circuit board integrated inductor in fig. 2 along III-III, fig. 4 is a schematic structural diagram of an embodiment of the circuit board integrated inductor provided in the present application, and fig. 5 is a schematic cross-sectional structure diagram of an embodiment of the circuit board integrated inductor in fig. 4 along V-V.

In the present application, the electronic device 10 may be a portable device such as a mobile phone, a tablet computer, a notebook computer, and a wearable device. In the embodiment, the electronic device 10 is taken as a mobile phone for exemplary description.

Referring to fig. 1, an electronic device 10 may include a display module 11, a middle frame 12, and a rear cover 13. The display module 11 and the rear cover plate 13 are respectively located on two opposite sides of the middle frame 12, and can be assembled and connected with the middle frame 12 through one or a combination of assembling modes such as gluing, clamping, welding and the like, so that a basic structure that the display module 11 and the rear cover plate 13 clamp the middle frame 12 together is formed after the three are assembled. Further, the display module 11, the rear cover plate 13 and the middle frame 12 may form a cavity with a certain volume, and the cavity may be used to mount structural members such as the camera module 14, a motherboard, and a battery, so that the electronic device 10 can implement corresponding functions. The display module 11, the camera module 14 and other components can be respectively electrically connected to the motherboard, the battery and the like through a Flexible Printed Circuit (FPC), so that they can obtain the power supply of the battery, and can execute corresponding instructions under the control of the motherboard.

Generally, the inductor may be composed of a coil and a magnetic member. When alternating current passes through the coil, alternating magnetic flux is generated inside and around the coil, so that the inductor has the function of storing and releasing energy. Furthermore, the inductor has a current limiting function on alternating current, so that the inductor and the resistor or the capacitor can form a high-pass filter or a low-pass filter, a phase shift circuit and a resonant circuit. However, with the trend of miniaturization and high density of electronic hardware, the space for supplying circuit boards is gradually reduced, and the demand for electronic components on the boards is increasing. For example: in the power module, the inductor occupies more than 40% of the surface of the power board, which is not only unfavorable for the miniaturization and high density of the product; and most inductors need to be separately mounted, so that the packaging efficiency is reduced. Therefore, the present application provides a circuit board integrated inductor 100, i.e. the inductor is integrated on the circuit board without discrete mounting, thereby improving the packaging efficiency. The circuit board integrated inductor 100 described herein may be applied to the electronic device 10.

As an example, the circuit board integrated inductor 100 may include a substrate 101, a coil pattern 102, and a dielectric layer 103, the coil pattern 102 being located on at least one side of the substrate 101, the dielectric layer 103 covering the coil pattern 102 or being surrounded by the coil pattern 102. The coil pattern 102 may be floating on the surface of the substrate 101, or may be at least partially embedded in the substrate 101. Further, the thickness of the substrate 101 may be between 10 μm and 60 μm. It is worth noting that: the mechanical property is limited due to the fact that the thickness of the substrate 101 is too small, and the copper coils on the upper surface and the lower surface cannot be effectively supported; too large a thickness of the substrate 101 increases the magnetic resistance, which is detrimental to the resulting inductance performance. The wire thickness of each turn of the coil in the coil pattern 102 may be between 50 μm and 150 μm, the line width of each turn of the coil may be between 100 μm and 300 μm, and the wire distance between two adjacent turns may be between 80 μm and 200 μm.

It should be noted that: the coil pattern 102 may be an integer turn coil such as a one-turn coil, a two-turn coil, or a three-turn coil, or may be a non-integer turn coil such as a half-turn coil or a one-turn and half-turn coil. Under the same condition, the more the number of turns of the coil pattern 102 is, the greater the inductance of the circuit board integrated inductor 100 is. Further, the circuit board integrated inductor 100 may further include a packaging layer, where the packaging layer is used to delay the erosion of external water and oxygen to the functional layers such as the coil pattern 102, the dielectric layer 103, and the magnetic film layer 104. The encapsulation layer may be an organic layer or an inorganic layer, or may be an organic/inorganic composite layer.

In some embodiments, such as fig. 2 and 3, the coil patterns 102 may be formed on opposite sides of the substrate 101 and conducted through the metalized vias 106 on the substrate 101; that is, the coils in the coil pattern 102 are disposed through the substrate 101.

In other embodiments, such as fig. 4 and 5, the coil pattern 102 may be formed on one side of the substrate 101, that is, the coils in the coil pattern 102 are located on one side of the substrate 101. Further, the circuit board integrated inductor 100 may further include a reinforcing structure 107 attached to a side of the substrate 101 away from the coil pattern 102, where the reinforcing structure 107 is used to increase the structural strength of the circuit board integrated inductor 100, so as to meet the use requirements of different scenarios. The reinforcing structure 107 may be a plastic part (such as a glass fiber/epoxy composite board) or a metal part (such as a copper foil).

In other embodiments, the circuit board integrated inductor 100 may have a multi-layer structure, that is, at least one of the circuit board integrated inductors 100 shown in fig. 2 and 3 is stacked according to a certain rule, and the same coil in the adjacent circuit board integrated inductors 100 is conducted.

Illustratively, the circuit board integrated inductor 100 may further include a magnetic film layer 104 on a side of the dielectric layer 103 facing away from the substrate 101, and a relative permeability of the magnetic film layer 104 is greater than a relative permeability of the dielectric layer 103, so that the circuit board integrated inductor 100 has a higher inductance. The dielectric layer 103 may planarize the surface of the circuit board integrated inductor 100 to further form the magnetic film layer 104 thereon, and may also function as a dielectric layer to electrically isolate the coil pattern 102 from the magnetic film layer 104. Accordingly, the thickness of the dielectric layer 103 may be based on the coverage of the coil pattern 102, for example, between 50 μm and 500 μm. Of course, in other embodiments, such as those with low inductance requirements, the circuit board integrated inductor 100 may not include the magnetic film layer 104. Further, the dielectric layer 103 may also only serve to planarize the surface of the integrated inductor 100 of the circuit board without magnetism, for example, the dielectric layer 103 includes resin and does not include magnetic particles, and for example, the dielectric layer 103 is a glass fiber/epoxy composite board, a polyimide film, etc. and is covered on the coil pattern 102 through a lamination process.

Further, the magnetic film layer 104 may further have a plurality of holes 105, such that the eddy current in the magnetic film layer 104 is blocked by the holes 105, thereby reducing the eddy current loss while maintaining the inductance of the circuit board integrated inductor 100 substantially unchanged.

Illustratively, the eddy current loss of the circuit board integrated inductor 100 when the magnetic film 104 has the hole 105 may be reduced by at least 76% compared to the eddy current loss when the magnetic film 104 does not have the hole 105, and the inductance of the circuit board integrated inductor 100 when the magnetic film 104 has the hole 105 may be at least 86% of the inductance of the magnetic film 104 without the hole 105. In other words, compared to the magnetic film 104 without the hole 105, the inductance of the pcb integrated inductor 100 can still be maintained 86% when the magnetic film 104 passes through the hole 105 to reduce the eddy current loss of the pcb integrated inductor 100 by 76%. Preferably, the eddy current loss of the circuit board integrated inductor 100 when the magnetic film 104 has the hole 105 can be reduced by at least 33% compared to the eddy current loss when the magnetic film 104 does not have the hole 105, and the inductance of the circuit board integrated inductor 100 when the magnetic film 104 has the hole 105 can be at least 99% of the inductance when the magnetic film 104 does not have the hole 105.

As an example, the area of the projection of each hole 105 onto the substrate 101 may be between 400 μm ² And 3600 μm ² To (c) to (d); specifically, the area of the projection of each hole 105 orthographically projected to the substrate 101 may be 400 μm ² 、800μm ² 、1200μm ² 、1600μm ² 、2400μm ² 、3600μm ² And the like. Further, the number of holes 105 may be between 2 and 40 per square millimeter of area; specifically, the number of holes 105 may be 2, 4, 8, 17, 40, etc. per square millimeter of area.

The holes 105 may be through holes or blind holes, for example. The holes 105 may be circular or square, i.e. other regular or irregular shapes, as viewed along the thickness direction of the magnetic film layer 104 pointing to the substrate 101. Further, the plurality of holes 105 make the magnetic film layer 104 in a continuous grid shape when viewed along a thickness direction of the magnetic film layer 104 pointing to the substrate 101, so that the circuit board integrated inductor 100 maintains a high inductance. Of course, in other embodiments, such as those with low inductance requirements, the plurality of holes 105 may also make the magnetic film layer 104 partially discontinuous, that is, the magnetic film layer 104 has islands discontinuous with other parts.

Next, the circuit board integrated inductor 100 shown in fig. 4 is taken as an example, and the circuit board integrated inductor 100 is further described with reference to some specific examples. The circuit board integrated inductor 100 may include a substrate 101 and a coil pattern 102 attached to one side of the substrate 101, and a dielectric layer 103 and a magnetic film layer 104 are sequentially disposed on both sides of the substrate 101. Further, the outer contour dimension of the substrate 101 is 5mm × 5mm, and the thickness is 50 μm; the coil pattern 102 is a one-turn coil, the line width and the line thickness of the coil are 260 μm and 100 μm respectively, the space between two opposite sides of the coil is 2.48mm, and the space between (positive and negative) lead wires connected with an external circuit is 100 μm; the substrate 101 is made of a glass fiber/epoxy composite material, and the coil pattern 102 is made of copper; the magnetic film layer 104 is made of FeNi alloy, and has a relative magnetic permeability of 100 and an electrical conductivity of 200KS/m. Based on this, the circuit board integrated inductor 100 with the magnetic film layer 104 without the holes 105 is used as a comparative example, and the circuit board integrated inductor 100 with the magnetic film layer 104 with the holes 105 of different sizes and numbers is used as a different embodiment, which is specifically shown in table 1 and table 2 below. Wherein the holes 105 are square. Further, inductance characteristics of the integrated inductors 100 of the circuit boards corresponding to the different embodiments and comparative examples were respectively tested. The inductance characteristic test standard is as follows: GB/T8554-1998.

Table 1:

	comparative example	Example 1	Example 2	Example 3
					Pore size/. Mu.m	/	20	40	60
inductance/nH	23.75	23.63	23.58	20.42
					Eddy current loss/mW	8.50	7.91	5.69	2.00

Table 2:

combining table 1 and table 2, it can be seen that: under the same condition, compared with the magnetic film layer 104 without the hole 105, the magnetic film layer 104 with the hole 105 is beneficial to reducing the eddy current loss under the condition that the inductance of the circuit board integrated inductor 100 is kept substantially unchanged. Further, under the same condition, the larger the area of the holes 105 on the magnetic film layer 104 is, the better the blocking effect of each hole 105 on the eddy current in the magnetic film layer 104 is, and the more beneficial the circuit board integrated inductor 100 to greatly reduce the eddy current loss under the condition of maintaining the inductance substantially unchanged. Further, under the same condition, the larger the number of the holes 105 on the magnetic film layer 104, the better the blocking effect of the holes 105 on the eddy current in the magnetic film layer 104, and the more favorable the eddy current loss is greatly reduced under the condition that the inductance of the circuit board integrated inductor 100 is kept substantially unchanged.

The inventors of the present application found in long-term research and development work that: the dielectric layer 103 may be cured from, for example, magnetic paste printed on the substrate 101, but the introduction of the magnetic paste may cause some technical problems. For example: in order to ensure that the difference between the actual size of the dielectric layer 103 and the design value is small, the viscosity of the magnetic slurry cannot be too low to prevent overflow; however, if the ratio of the magnetic powder to the resin matrix is raised to a higher level in order to raise the viscosity of the magnetic slurry, severe delamination of the magnetic powder and the resin matrix due to a difference in density may be caused. For another example: during curing such as thermal curing, the viscosity of the magnetic paste decreases with increasing curing temperature, which may cause some collapse of the edges of the dielectric layer 103 (e.g., the square shape of the initial design may become a slope with a high probability), thereby affecting the matching of the design and testing effects of the dielectric layer 103, and affecting the subsequent package size design and product uniformity. Therefore, the application provides a method for manufacturing the circuit board integrated inductor 100, which limits the magnetic paste by arranging the retaining wall structure to prevent the magnetic paste from overflowing in the process of curing to form the dielectric layer 103, thereby allowing the magnetic paste to have lower viscosity to better cover the coil pattern 102, reducing the risk of collapse of the edge of the dielectric layer 103, and also improving the precision of the shape, the size and the like of the dielectric layer 103.

Referring to fig. 6 to 7 together, fig. 6 is a schematic flowchart of an embodiment of a method for manufacturing the circuit board integrated inductor provided by the present application, and fig. 7 is a schematic structural diagram corresponding to different steps in a manufacturing process of the circuit board integrated inductor in fig. 6. It should be noted that: for convenience of description, the following describes a method for manufacturing a circuit board integrated inductor in a specific sequence of steps; however, the circuit board integrated inductor may be fabricated in a different sequence of steps, with additional steps added or certain steps reduced (combined). The manufacturing method of the present embodiment may include:

step S11: a coil pattern is formed on the circuit board.

As an example, the circuit board 200 may be a single-layer copper-clad plate, that is, includes a substrate 201 and a copper foil 202 attached to one side of the substrate 201; the circuit board 200 may also be a double-layer copper-clad plate, that is, it includes a substrate 201 and copper foils 202 attached to two opposite sides of the substrate 201. The substrate 201 may be a hard substrate such as a glass fiber/epoxy composite board, or a soft substrate such as a polyimide film. Further, the coil pattern 102 on the circuit board 200 may be formed by etching, etc., which is well known to those skilled in the art and will not be described herein.

In some embodiments, such as where circuit board 200 is a two-layer copper-clad board, for example, fig. 7, coil pattern 102 may be formed on circuit board 200 by: forming a through hole on a substrate 201 through a laser through hole process, and forming a conductive layer on the wall of the through hole through a black hole process, namely forming a metalized through hole 106 on the substrate 201; then, the copper foils 202 on both sides of the substrate 201 are patterned by an etching process to form the coil patterns 102, and the coil patterns 102 on both sides of the substrate 201 are conducted through the corresponding metalized vias 106.

In some embodiments, such as the circuit board is a single-layer copper clad laminate, for example, as shown in fig. 9, the coil pattern 102 can be formed by patterning the copper foil 202 on the substrate 201 through an etching process.

Step S12: and forming a retaining wall structure surrounding the coil pattern on the circuit board.

As an example, the retaining wall structure 300 may be a structure with a certain strength to define the filling range of the magnetic paste in the subsequent manufacturing process, so as to prevent the magnetic paste from overflowing during the process of curing to form the dielectric layer 103. The retaining wall structure 300 can be fabricated in advance for direct use, or can be fabricated directly during use. Further, the retaining wall structures 300 may be higher than the coil patterns 102 to allow the magnetic paste to cover the coil patterns 102 in a subsequent manufacturing process, thereby forming a basic structure in which the dielectric layer 103 covers the coil patterns 102. Of course, the dam structures 300 may be flush with the coil patterns 102 to allow the magnetic paste to fill the coil patterns 102 in the subsequent manufacturing process, thereby forming a basic structure in which the dielectric layer 103 is surrounded by the coil patterns 102. Accordingly, the thickness of the magnetic slurry may be equal to the height of the retaining wall structure 300.

In some embodiments, such as fig. 7, the retaining wall structure 300 may be formed on the circuit board 200 by: firstly, a photosensitive film 400 is disposed on the circuit board 200, for example, the photosensitive film 400 is a dry film attached to the circuit board 200, and then, for example, the photosensitive film 400 is a photosensitive glue coated on the circuit board 200; then, a certain region of the photosensitive film 400 is exposed and developed, and other regions of the photosensitive film 400 are washed away to form the bank structures 300. Wherein, the specific region of the photosensitive film 400 is the region of the photosensitive film 400 used as the dam structure 300, i.e. the region surrounding the coil pattern 102; other areas of the photosensitive film 400 may include an area where the photosensitive film 400 covers the coil pattern 102. Further, when the photosensitive film 400 is a dry film attached to the circuit board 200, the height of the dam structure 300 may be a positive integer multiple of the number of layers of the dry film. For example: the thickness of the dry film is about 25 μm, and the thickness of the magnetic slurry is about 50 μm, so that the retaining wall structure 300 with a height of about 50 μm can be formed by using two layers of dry films. Of course, the retaining wall structure 300 may also be formed by curing thermosetting adhesive.

In other embodiments, such as fig. 7, the retaining wall structure 300 may be formed on the circuit board 200 by the following steps: firstly, a reinforcing plate 500 is arranged on a circuit board 200, for example, the reinforcing plate 500 is attached to the circuit board 200, and then, for example, the circuit board 200 and the reinforcing plate 500 are stacked and clamped by an external object; then, a certain region of the reinforcing plate 500 is subjected to a removal process to form the retaining wall structure 300. The specific area of the reinforcing plate 500 is the area of the reinforcing plate 500 covering the coil pattern 102, so that the retaining wall structure 300 can be obtained by milling the specific area of the reinforcing plate 500 covering the coil pattern 102 by the processes of routing, drilling and the like. Of course, the retaining wall structure 300 may be a reinforcing plate 500 disposed on the circuit board 200, and a specific region of the reinforcing plate 500 has been removed; that is, the frame-shaped reinforcing plate 500 is directly attached to the circuit board 200, and the retaining wall structure 300 can also be formed on the circuit board 200. Further, the reinforcing plate 500 may be a plastic member (such as a glass fiber/epoxy composite plate) or a metal member (such as a copper foil).

It should be noted that: the circuit board 200 may have a plurality of coil patterns 102 formed thereon; accordingly, the circuit board 200 has a plurality of wall structures 300 surrounding the coil patterns 102, and each wall structure 300 may surround one coil pattern 102. Thus, a plurality of integrated inductors 100 of the circuit board can be manufactured at one time, i.e. "one mold with a plurality of pieces", thereby improving the manufacturing efficiency.

Step S13: and filling magnetic slurry in the region surrounded by the retaining wall structure.

As an example, the magnetic paste may include a resin that provides the magnetic paste with certain fluidity and viscosity, and magnetic particles dispersed in the resin that provide the magnetic paste with certain magnetism. Wherein, the magnetic particles can be one or the combination of soft magnetic ferrite (such as MnZn ferrite, niZn ferrite, etc.) or soft magnetic alloy (such as FeSiAl, feSiB, etc.). It is worth noting that: when higher electrical insulation properties and lower eddy current losses are required, the magnetic particles may preferably be soft magnetic ferrites; whereas when higher relative permeability and saturation induction are required, the magnetic particles may preferably be a soft magnetic alloy. Further, the weight fraction of the magnetic particles may be between 30% and 90%, and the D90 particle size of the magnetic particles may be between 5 μm and 50 μm. It is worth noting that: on one hand, the relative permeability of the magnetic slurry is too low due to too low mass fraction of the magnetic particles, so that the relative permeability of the dielectric layer 103 (formed by curing the magnetic slurry) is too low, and the use value is lost; too high mass fraction of the magnetic particles may result in insufficient fluidity of the magnetic paste, which may make it difficult for the magnetic paste to fill the gaps of the coil pattern 102. On the other hand, if the particle size of the magnetic particles is too small, the relative permeability of the dielectric layer 103 (formed by curing the magnetic slurry) will be too low, and the use value will be lost; the excessive particle size of the magnetic particles will result in higher eddy current loss in the dielectric layer 103.

Further, the magnetic slurry may be filled in the region surrounded by the retaining wall structure 300 through processes such as steel mesh printing, coating, and dispensing. Due to the limiting effect of the retaining wall structure 300, the viscosity of the magnetic slurry can be relatively low, so that the selection range of the resin is increased. In addition to this, the magnetic paste may also better fill the gaps of the coil pattern 102.

Step S14: and curing the magnetic slurry to form a dielectric layer.

Illustratively, the magnetic paste is subjected to light irradiation under ultraviolet light such as an LED lamp or a mercury lamp, so that the resin in the magnetic paste undergoes a photocuring reaction and is cured, thereby forming the dielectric layer 103. Of course, the magnetic paste is subjected to a heating process, and the resin in the magnetic paste can also be cured, thereby forming the dielectric layer 103. In other words, the manner in which the magnetic paste is cured may depend on the chemical nature of the resin therein.

Through the above manner, in the process of manufacturing the circuit board integrated inductor 100 according to the embodiment, the retaining wall structure 300 limits the magnetic paste, so that the magnetic paste can be prevented from overflowing in the process of forming the dielectric layer 103 through curing, the coil pattern 102 can be better covered by the magnetic paste with low viscosity, the risk of collapse of the edge of the dielectric layer 103 can be reduced, and the precision of the dielectric layer 103, such as shape and size, can be improved.

It should be noted that: after the magnetic film layer 103 is formed or the entire circuit board integrated inductor 100 is manufactured, the retaining wall structure 300 can be removed, for example, by etching to clean the photosensitive film 400 or directly cutting the device units with precise cutting blade size according to the design, thereby obtaining a light and small finished product. When the retaining wall structure 300 is the reinforcing plate 500 and the specific area of the reinforcing plate 500 is removed, removing the retaining wall structure 300 may also mean peeling the reinforcing plate 500 from the circuit board 200, so that the reinforcing plate 500 can be reused, thereby reducing the manufacturing cost. Further, in other embodiments where the retaining wall structure 300 has the ability to exclude water and oxygen or the finished product does not need to be light and small, the retaining wall structure 300 may be retained, thereby improving the manufacturing efficiency.

Step S15: and forming a magnetic film layer on the medium layer, wherein the relative permeability of the magnetic film layer is greater than that of the medium layer.

Illustratively, the composition of the magnetic film layer 104 may include at least one of a soft magnetic alloy such as an iron-based crystalline state (e.g., feNi, etc.), an iron-based amorphous state (e.g., feSiB, etc.), a cobalt-based amorphous state (e.g., coFeSiB, coFeCrSiB, etc.), and the like. It is worth noting that: when a higher relative permeability is desired, the magnetic film layer 104 may preferably be a cobalt-based amorphous alloy; when higher saturation magnetic characteristics are required, the magnetic film layer 104 may preferably be an iron-based crystalline alloy and an iron-based amorphous alloy; while when a lower coercivity is desired, the magnetic film layer 104 may preferably be an iron-based crystalline alloy and a cobalt-based amorphous alloy. Wherein, the relative permeability of the magnetic film layer 104 can be larger than that of the dielectric layer 103, so that the circuit board integrated inductor 100 has higher inductance.

Further, the magnetic film layer 104 may be formed on the dielectric layer 103 by a physical vapor deposition or electrodeposition process. The dielectric layer 103 planarizes the circuit board integrated inductor 100, which is beneficial to forming the magnetic film layer 104 by deposition. It is noted that: when the thickness of the magnetic film layer 104 is less than 1 μm, a physical vapor deposition process is preferred to ensure the surface topography of the magnetic film layer 104; when the thickness of the magnetic film layer 104 is greater than 1 μm, the electrodeposition process is preferred to prevent the magnetic film layer 104 from peeling off. Thus, the thickness of the magnetic film layer 104 may be between 0.1 μm and 30 μm. It is worth noting that: the magnetic film layer 104 is too thin, so that the contribution is limited, the effective relative permeability is low, and the use value is lost; the excessive thickness of the magnetic film layer 104 will cause the eddy current loss therein to be large, and the difficulty of deposition will be increased accordingly.

Step S16: and carrying out hole treatment on the magnetic film layer.

Illustratively, the magnetic film layer 104 is etched by a laser etching method, so that the magnetic film layer 104 forms a hole structure. The area of a single hole can be controlled through the size of a light spot etched by laser. Further, the larger the area of the holes on the magnetic film layer 104 is, the larger the number is, and the more obvious the eddy current loss is reduced; however, the magnetic permeability of the magnetic film layer 104 decreases, so that the magnetic resistance increases, and the inductance decreases. Therefore, the size and the number of the holes can depend on the requirements of the inductance and the eddy current loss, so that the inductance and the eddy current loss are balanced to meet the use requirements of different application scenes. Preferably, the magnetic film layer 104 is in a grid-like structure.

It should be noted that: after step S16, an organic layer and/or an inorganic layer may also be deposited on the magnetic film layer 104 to form an encapsulation layer. Of course, in embodiments where the circuit board integrated inductor 100 does not include the magnetic film layer 104, organic and/or inorganic layers may also be deposited on the dielectric layer 103. Further, in some embodiments, such as the embodiment where the dielectric layer 103 is formed on one side of the circuit board 200, the steps S12 to S14 may be performed once; in other embodiments, such as embodiments in which the dielectric layers 103 are formed on two sides of the circuit board 200, the steps S12 to S14 may be repeated twice, for example, the dielectric layer 103 is formed on one side of the circuit board 200 and then the dielectric layer 103 is formed on the other side of the circuit board 200.

Referring to fig. 8 and 9 together, fig. 8 is a schematic flowchart of an embodiment of a method for manufacturing the circuit board integrated inductor provided by the present application, and fig. 9 is a schematic structural diagram corresponding to different steps in a manufacturing process of the circuit board integrated inductor in fig. 8. It should be noted that: for convenience of description, the method for manufacturing the integrated inductor of a certain circuit board will be described in a specific sequence of steps; however, the circuit board integrated inductor may be fabricated in a different sequence of steps, with additional steps added or certain steps reduced (combined). The manufacturing method of the present embodiment may include:

step S21: a coil pattern is formed on one side of the circuit board.

As an example, the circuit board 200 may be a single-layer copper clad laminate, that is, includes a substrate 201 and a copper foil 202 attached to one side of the substrate 201. The copper foil 202 on one side of the substrate 201 is patterned by an etching process, so that the coil pattern 102 is formed.

Step S22: a through hole surrounded by the coil pattern is formed on the circuit board.

Illustratively, the substrate 201 inside the coil pattern 102 is removed by routing, laser, or the like to form a via 203. Wherein the substrate 201 inside the coil pattern 102 may be partially or entirely removed.

Step S23: and a reinforcing plate is arranged on the other side of the circuit board, which is far away from the coil pattern, and a groove communicated with the through hole is formed in one side of the reinforcing plate, which faces the circuit board.

Illustratively, the reinforcing plate 500 has a thickness so as to form a blind hole thereon by routing, laser, etc. to form the groove 501. The reinforcing plate 500 may be a plastic part (such as a glass fiber/epoxy composite plate) or a metal part (such as a copper foil). Further, the reinforcing plate 500 is attached to the circuit board 200, or the circuit board 200 and the reinforcing plate 500 are stacked and clamped by an external object; the reinforcing plate 500 and the coil pattern 102 are located on opposite sides of the substrate 201, and the groove 501 is communicated with the through hole 203. Wherein, the area of the groove 501 may be greater than or equal to the area of the through hole 203. Further, when the coil pattern 102 is orthographically projected to the reinforcing plate 500, the coil pattern 102 may surround the groove 501, so that after the groove 501 is filled with the magnetic slurry and the magnetic slurry is cured to form the dielectric layer, the coil pattern 102 may surround the dielectric layer 103, so that the magnetic field of the circuit board integrated inductor 100 is more concentrated and the utilization rate is higher.

It should be noted that: step S22 and step S23 may also be combined into one, for example, the reinforcing plate 500 is firstly attached to the circuit board 200, and then the substrate 201 inside the coil pattern 102 is removed by routing, laser, and other processes to form a through hole 203, and further the reinforcing plate 500 is partially removed to form a groove 501. Further, the circuit board 200 may have a plurality of coil patterns 102 formed thereon; accordingly, the circuit board 200 is formed with a plurality of through holes 203 surrounded by the coil patterns 102, and the reinforcing plate 500 is formed with a plurality of grooves 501 communicating with the through holes 203, each coil pattern 102 may surround one through hole 203, and each through hole 203 may communicate with one groove 501. Thus, a plurality of integrated inductors 100 of the circuit board can be manufactured at one time, i.e. "one mold with a plurality of pieces", thereby improving the manufacturing efficiency.

Step S24: and filling the magnetic slurry into the groove through the through hole.

As an example, the magnetic paste may include a resin that provides the magnetic paste with certain fluidity and viscosity, and magnetic particles dispersed in the resin that provide the magnetic paste with certain magnetism. Wherein, the magnetic particles can be one or the combination of soft magnetic ferrite (such as MnZn ferrite, niZn ferrite, etc.) or soft magnetic alloy (such as FeSiAl, feSiB, etc.). It is worth noting that: when higher electrical insulation properties and lower eddy current losses are required, the magnetic particles may preferably be soft magnetic ferrites; whereas when higher relative permeability and saturation induction are required, the magnetic particles may preferably be a soft magnetic alloy. Further, the weight fraction of the magnetic particles may be between 30% and 90%, and the D90 particle size of the magnetic particles may be between 5 μm and 50 μm. It is worth noting that: on one hand, the relative permeability of the magnetic slurry is too low due to too low mass fraction of the magnetic particles, so that the relative permeability of the dielectric layer 103 (formed by curing the magnetic slurry) is too low, and the use value is lost; too high mass fraction of the magnetic particles may result in insufficient fluidity of the magnetic paste, which may make it difficult for the magnetic paste to fill the gaps of the coil pattern 102. On the other hand, the too small particle size of the magnetic particles can cause the relative magnetic permeability of the dielectric layer 103 (formed by curing the magnetic slurry) to be too low, and the use value is lost; the excessive particle size of the magnetic particles will result in higher eddy current loss in the dielectric layer 103.

Further, the magnetic slurry may be filled into the groove 501 through the through hole 203 by a drip irrigation, a dispensing, or the like process. Due to the limiting effect of the reinforcing plate 500, the viscosity of the magnetic slurry can be relatively low, and the selection range of the resin is increased. Further, the magnetic paste may be flush with a side of the coil pattern 102 away from the stiffener 500, so as to prevent the magnetic paste from overflowing too much and flowing too little to reduce the inductance.

Step S25: and carrying out curing treatment on the magnetic slurry to form a dielectric layer.

Illustratively, the magnetic paste is subjected to light irradiation under ultraviolet light such as an LED lamp or a mercury lamp, so that the resin in the magnetic paste undergoes a photocuring reaction and is cured, thereby forming the dielectric layer 103. Of course, the magnetic paste is subjected to a heating process, and the resin in the magnetic paste may also be cured, thereby forming the dielectric layer 103. In other words, the manner in which the magnetic paste is cured may depend on the chemical nature of the resin therein.

Through the above manner, in the process of manufacturing the circuit board integrated inductor 100 according to the embodiment, the reinforcing plate 500 limits the magnetic paste in the groove 501, and the magnetic paste can be prevented from overflowing in the process of curing to form the dielectric layer 103, so that the magnetic paste is allowed to have a lower viscosity and be better surrounded by the coil pattern 102, the risk of collapse occurring at the edge of the dielectric layer 103 is reduced, and the accuracy of the shape, the size and the like of the dielectric layer 103 is also improved.

It should be noted that: after the magnetic film layer 103 is formed or the whole circuit board integrated inductor 100 is manufactured, the reinforcing plate 500 can be peeled off from the circuit board 200, so that a light and small semi-finished product or finished product is obtained. In addition, the reinforcing plate 500 can be reused, thereby reducing the manufacturing cost. Further, after step S25, an organic layer and/or an inorganic layer may also be deposited on the magnetic film layer 104 to form an encapsulation layer. Similarly, after step S25, a magnetic film layer 104 may be further formed on the dielectric layer 103, the relative permeability of the magnetic film layer 104 is greater than that of the dielectric layer 103, and the magnetic film layer 104 may be subjected to a hole processing, which is not described herein again.

The above description is only a part of the embodiments of the present application, and not intended to limit the scope of the present application, and all equivalent devices or equivalent processes performed by the content of the present application and the attached drawings, or directly or indirectly applied to other related technical fields, are also included in the scope of the present application.

Claims

1. The integrated inductor of the circuit board is characterized by comprising a substrate, a coil pattern, a dielectric layer and a magnetic film layer, wherein the coil pattern is positioned on at least one side of the substrate, the dielectric layer covers the coil pattern, and the magnetic film layer is positioned on one side of the dielectric layer, which is far away from the substrate; the relative permeability of the magnetic film layer is larger than that of the medium layer, and the magnetic film layer is provided with a plurality of holes.

2. The circuit board integrated inductor of claim 1, wherein the area of the projection of each hole orthogonal to the substrate is between 400 μm ² And 3600 μm ² In the meantime.

3. The circuit board integrated inductor of claim 1, wherein the number of holes is between 2 and 40 per square millimeter of area.

4. The circuit board integrated inductor of claim 1, wherein the hole is a through hole.

5. The circuit board integrated inductor of claim 4, wherein the hole is circular or square when viewed along a thickness direction of the magnetic film layer pointing to the substrate.

6. The integrated inductor of circuit board according to claim 4, wherein the plurality of holes make the magnetic film layer in a continuous grid shape when viewed along a thickness direction of the substrate where the magnetic film layer points.

7. The circuit board integrated inductor of claim 1, wherein the composition of the magnetic film layer comprises at least one of an iron-based crystalline alloy, an iron-based amorphous alloy, and a cobalt-based amorphous alloy.

8. The circuit board integrated inductor of claim 1, wherein the dielectric layer comprises a resin and magnetic particles dispersed in the resin; wherein the D90 particle size of the magnetic particles is between 5 μm and 50 μm.

9. An electronic device characterized in that it comprises a circuit board integrated inductor according to any of claims 1-8.