Thin film inductor structure and method of manufacturing the same

Abstract

The application provides a thin-film inductor structure and a preparation method thereof. The thin-film inductor structure comprises a first substrate layer, a first coil layer, an insulating layer, a second coil layer and a second substrate layer. The material of the first filling part and the second filling part independently comprises a soft magnetic alloy, a thermosetting resin and a thermoplastic resin. In the thin-film inductor structure, the filling parts arranged in the first coil layer and the second coil layer compensate for the height difference between the thick electrode coil and the substrate layer in the prior art. At the same time, the soft magnetic alloy, the thermosetting resin and the thermoplastic resin are used as the filling part material, and the surface of the filling part is flush with the surface of the electrode coil, which greatly improves the interlayer combination of the substrate magnetic sheet and the coil layer during subsequent compression treatment, and promotes the combination of the substrate magnetic sheet and the coil layer. Under the above two factors, the cracking and even serious delamination of the thin-film inductor during subsequent cutting are avoided.

Description

Technical Field

[0001] This invention relates to the field of thin-film inductors, and more specifically, to a thin-film inductor structure and its preparation method. Background Technology

[0002] With the rapid development of electronic power, the demand for high-power, high-current inductors is increasing. In high-power, high-current applications, low-loss, low-cost, and high-conversion-efficiency alloy magnetic materials are becoming increasingly popular. CN105590747B discloses a power-type component and its manufacturing method. It is manufactured using the LTCC process, where silver paste is used to increase the silver layer thickness to achieve high current resistance. However, this process has significant limitations in miniaturizing inductors, making it difficult to mass-produce inductors smaller than 1.6×0.8mm. CN110060836A discloses a multilayer conductive patterned inductor and its manufacturing method. It uses a method of first fabricating a coil layer and then directly stacking magnetic sheets on the upper and lower surfaces of the coil layer. Due to the open spaces between the electrodes in the coil section, directly stacking planar magnetic sheets easily leads to uneven inductor thickness. CN110660554A discloses a high-permeability, high-frequency planar inductor and its preparation method. Its soft magnetic thin film is formed using magnetron sputtering, but this method is costly, inefficient, and difficult to control in forming thick films.

[0003] Currently, the trend towards miniaturization and integration of electronics is becoming increasingly clear. Traditional wire-winding and monolithic molding processes are increasingly unable to meet development requirements. Therefore, developing smaller and thinner thin-film power inductors has become an inevitable trend. To ensure the high saturation current characteristic of thin-film inductors, the electrode coil must either have a wider line width or a thicker line. However, due to the size limitations of inductors, widening the line width inevitably sacrifices inductance. Therefore, for electrode coils, increasing the line thickness to improve saturation current is more advantageous. However, for traditional sandwich-structured thin-film inductors, increasing the line thickness can lead to insufficient adhesion between the substrate magnetic sheet and the coil lamination due to excessive thickness differences in the electrode pattern area. This can result in product cracking or even delamination during cutting.

[0004] Therefore, it is necessary to provide a thin-film inductor that has better bonding between its coil layer and the substrate magnetic sheet, making it less prone to cracking or even severe delamination during cutting. Summary of the Invention

[0005] The main objective of this invention is to provide a thin-film inductor structure and its preparation method, in order to solve the problem in the prior art where the poor bonding between the coil layer and the substrate magnetic sheet is caused by the thick coil, which easily leads to cracking or even severe delamination during cutting.

[0006] To achieve the above objectives, according to one aspect of the present invention, a thin-film inductor structure is provided, comprising: a first substrate layer having a first surface, the first surface being divided into a first region and a second region; a first coil layer disposed on the first surface of the first substrate layer, the first coil layer including a first electrode coil and a first filling portion, the first electrode coil being disposed in the first region and the first filling portion being disposed in at least a portion of the second region; an insulating layer disposed on the surface of the first coil layer away from the first substrate layer, the surface of the insulating layer away from the first substrate layer being divided into a third region and a fourth region, and the vertical projection of the third region on the first surface completely coincides with the first region; a second coil layer disposed on the surface of the insulating layer away from the first substrate layer, the second coil layer including a second electrode coil and a second filling portion, the second electrode coil being disposed in the third region and the second filling portion being disposed in at least a portion of the fourth region; and a second substrate layer disposed on the surface of the second coil layer away from the first substrate layer; wherein the materials of the first filling portion and the second filling portion each independently include a soft magnetic alloy, a thermosetting resin, and a thermoplastic resin.

[0007] Furthermore, the first electrode coil is flush with the surface of the first filling portion away from the first substrate layer; the second electrode coil and the surface of the second filling portion are flush with the surface of the second filling portion away from the first substrate layer.

[0008] Furthermore, the area where the first electrode coil contacts the first surface completely overlaps with the first region, and the first filling portion is disposed in the entire second region; the area where the second electrode coil contacts the surface of the insulating layer completely overlaps with the third region, and the second filling portion is disposed in the entire fourth region.

[0009] Furthermore, the thermosetting resin is selected from one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, silicone resin and epoxy modified silicone resin; the thermoplastic resin is selected from polymethyl methacrylate and / or polyvinyl butyral.

[0010] Furthermore, by weight, the materials of the first filling part and the second filling part each independently include 90 to 95 parts of soft magnetic alloy, 3 to 6 parts of thermosetting resin and thermoplastic resin, and 2 to 4 parts of thermoplastic resin.

[0011] Furthermore, the soft magnetic alloy is in granular form; preferably, the particle size of the soft magnetic alloy is 2–10 μm.

[0012] Further, the insulating layer is made of polyimide, polyester, polyimide, fluorocarbon film, or aromatic polyamide; preferably, the thickness of the insulating layer is 13-25 μm; preferably, the thin-film inductor structure further includes an adhesive layer, which is disposed between the first coil layer and the insulating layer, and between the second coil layer and the insulating layer; preferably, the adhesive layer is made of one or more of epoxy resin, acrylate resin, phenolic modified polyvinyl butyral resin, polyester resin, or polyimide resin; preferably, the thickness of the adhesive layer is 3-5 μm.

[0013] Furthermore, the materials of both the first filling part and the second filling part also include a curing agent and an accelerator; preferably, the curing agent is one or more of m-phenylenediamine, isoflurane diamine, diethyltoluene diamine or dicyandiamide; preferably, the accelerator is one or more of 2-methylimidazole, 2-ethyl-4-methylimidazole or salicylic acid.

[0014] Furthermore, the thickness of the first coil layer and the second coil layer are each independently 20 to 100 μm, and the thickness of the first substrate layer and the second substrate layer are each independently 50 to 200 μm.

[0015] To achieve the above objectives, according to one aspect of the present invention, a method for preparing the aforementioned thin-film inductor structure is provided. The method includes the following steps: fabricating a coil layer, the coil layer comprising a first coil layer, an insulating layer, and a second coil layer, the first coil layer comprising a first electrode coil and a first filling portion, and the second coil layer comprising a second electrode coil and a second filling portion; placing a first substrate layer on the side of the first coil layer away from the insulating layer, placing a second substrate layer on the side of the second coil layer away from the insulating layer, and hot-pressing to obtain a thin-film inductor structure; wherein the first substrate layer has a first surface, and the first surface is divided into a first region and a second region; the first electrode coil is disposed in the first region, and the first filling portion is disposed in at least a portion of the second region; the surface of the insulating layer away from the first substrate layer is divided into a third region and a fourth region, and the vertical projection of the third region on the first surface completely coincides with the first region; the second electrode coil is disposed in the third region, and the second filling portion is disposed in at least a portion of the fourth region; the materials of the first filling portion and the second filling portion each independently comprise a soft magnetic alloy, a thermosetting resin, and a thermoplastic resin.

[0016] Further, the steps for fabricating the coil layer include: adhering the first electrode coil and the second electrode coil to opposite sides of the insulating layer using an adhesive layer to form a pre-coil; placing the material of the first filling portion at the desired location on the insulating layer, with its height exceeding the first electrode coil by 3-5 μm; placing the material of the second filling portion at the desired location on the insulating layer, with its height exceeding the second electrode coil by 3-5 μm; obtaining the coil to be pressed; and performing a first hot-pressing treatment on the coil to be pressed to form the coil layer; preferably, in the first hot-pressing treatment step, the operating temperature is 65-80°C, the operating pressure is 2-8 MPa, and the operating time is 5-10 min.

[0017] Further, the hot-pressing process for preparing the thin-film inductor structure includes: sequentially performing a second hot-pressing treatment and an isostatic pressing treatment on the placed first substrate layer, coil layer, and second substrate layer to obtain the thin-film inductor structure; preferably, during the second hot-pressing treatment, the operating temperature is 100–150°C, the operating pressure is 15–20 MPa, and the operating time is 10–15 min; preferably, during the isostatic pressing treatment, the operating temperature is 60–80°C, the operating pressure is 40–60 MPa, and the operating time is 10–25 min.

[0018] In the thin-film inductor structure of this invention, the filling portions provided in the first and second coil layers compensate for the height difference between the thicker electrode coils and the substrate layer in the prior art. Simultaneously, this invention utilizes soft magnetic alloys, thermosetting resins, and thermoplastic resins as filling materials, and ensures their surfaces are flush with the electrode coil surfaces. This significantly improves the interlayer bonding between the substrate magnetic sheet and the coil layer during subsequent lamination, resulting in a stronger bond between them. These two factors prevent cracking or even severe delamination of the thin-film inductor during subsequent cutting. Attached Figure Description

[0019] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0020] Figure 1 A schematic diagram of a thin-film inductor structure according to Embodiment 1 of the present invention is shown; and

[0021] Figure 2 A schematic diagram of the thin-film inductor structure coil layer in Embodiment 1 of the present invention is shown.

[0022] The above figures include the following reference numerals:

[0023] 10. First substrate layer; 20. First coil layer; 21. First electrode coil; 22. First filling portion; 30. Insulating layer; 40. Second coil layer; 41. Second electrode coil; 42. Second filling portion; 50. Second substrate layer; 60. Adhesive layer. Detailed Implementation

[0024] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0025] As described in the background section, the existing technology suffers from poor bonding between the coil layer and the substrate magnetic sheet due to the thickness of the coil, which easily leads to cracking or even severe delamination during cutting.

[0026] To address this problem, the present invention provides a thin-film inductor structure, such as... Figure 1 As shown, the thin-film inductor structure includes a first substrate layer 10, a first coil layer 20, an insulating layer 30, a second coil layer 40, and a second substrate layer 50. The first substrate layer 10 has a first surface, which is divided into a first region and a second region. The first coil layer 20 is disposed on the first surface of the first substrate layer 10, and includes a first electrode coil 21 and a first filling portion 22. The first electrode coil 21 is disposed in the first region, and the first filling portion 22 is disposed in at least a portion of the second region. The insulating layer 30 is disposed on the surface of the first coil layer 20 away from the first substrate layer 10. The surface of layer 10 is divided into a third region and a fourth region, and the vertical projection of the third region onto the first surface completely coincides with the first region; the second coil layer 40 is disposed on the surface of the insulating layer 30 away from the first substrate layer 10, the second coil layer 40 includes a second electrode coil 41 and a second filling portion 42, the second electrode coil 41 is disposed in the third region, and the second filling portion 42 is disposed in at least part of the fourth region; the second substrate layer 50 is disposed on the surface of the second coil layer 40 away from the first substrate layer 10; wherein, the materials of the first filling portion 22 and the second filling portion 42 each independently include a soft magnetic alloy, a thermosetting resin and a thermoplastic resin.

[0027] First, in the thin-film inductor structure of this invention, by providing filling portions in the first and second coil layers, the height difference between the thicker electrode coil and the substrate layer in the prior art is compensated. Simultaneously, this invention utilizes soft magnetic alloy, thermosetting resin, and thermoplastic resin as filling portion materials, significantly improving the interlayer bonding between the substrate magnetic sheet and the coil layer during subsequent lamination processing, resulting in a stronger bond between the substrate magnetic sheet and the coil layer. These two factors prevent cracking or severe delamination in the middle area of ​​the thin-film inductor during subsequent cutting. Second, this invention uses thermoplastic resin, thermosetting resin, and soft magnetic alloy as raw materials to construct the first and second filling portions. This further improves the adhesion between the substrate magnetic sheet and the coil layer during subsequent lamination processing. Furthermore, it increases the product's strength, making it less prone to deformation. The thin-film inductor of the present invention does not require high-temperature sintering. After being fully cured at 180-220°C in subsequent processes, it can have a magnetic strength comparable to that of multilayer power inductors produced by conventional LTCC process through high-temperature sintering. It can meet the harsh operating environment of power inductors with a maximum temperature of 160°C and has a long service life.

[0028] To further balance the strength and bonding performance of the inductor, the first electrode coil 21 is flush with the surface of the first filling portion 22 that is away from the first substrate layer 10; the second electrode coil 41 and the surface of the second filling portion 42 that are away from the first substrate layer 10 are also flush.

[0029] To further improve the bonding force between the coil layer and the substrate layer, it is preferable that the area where the first electrode coil 21 contacts the first surface completely overlaps with the first region, and the first filling portion 22 is disposed in the entire second region; the area where the second electrode coil 41 contacts the surface of the insulating layer 30 completely overlaps with the third region, and the second filling portion 42 is disposed in the entire fourth region.

[0030] Preferably, the thermosetting resin is selected from one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, silicone resin, and epoxy-modified silicone resin; the thermoplastic resin is selected from polymethyl methacrylate and / or polyvinyl butyral. The materials of the first filler portion 22 and the second filler portion 42 can be the same or different. Based on the combination of the above-mentioned specific types of resins, the adhesion between the substrate magnetic sheet and the coil layer and the strength of the product are further improved during subsequent lamination processing. Specifically, the above-mentioned thermosetting resins include, but are not limited to, E44, E51, and E54; the thermoplastic resins include, but are not limited to, A21, B44, B76, B79, and B98.

[0031] To further balance the bonding force between the coil layer and the substrate layer and the strength characteristics of the product, the materials of the first filling portion 22 and the second filling portion 42, by weight, preferably each independently comprise 90-95 parts of soft magnetic alloy, 3-6 parts of thermosetting resin / thermoplastic resin, and 2-4 parts of thermoplastic resin. Preferably, the soft magnetic alloy is granular; more preferably, the particle size of the soft magnetic alloy is 2-10 μm (D50).

[0032] In a preferred embodiment, the insulating layer 30 is made of polyimide, polyester, polyimide, fluorocarbon film, or aromatic polyamide; preferably, the thickness of the insulating layer 30 is 13–25 μm. Preferably, the thin-film inductor structure further includes an adhesive layer 60, which is disposed between the first coil layer 20 and the insulating layer 30, and between the second coil layer 40 and the insulating layer 30; preferably, the adhesive layer 60 is made of one or more of epoxy resin, acrylate resin, phenolic modified polyvinyl butyral resin, polyester resin, or polyimide resin; preferably, the thickness of the adhesive layer 60 is 3–5 μm. The materials of the insulating layer and the adhesive layer described above are all commonly used materials in the art. Those skilled in the art can select appropriate materials according to their product requirements, and will not be elaborated further here.

[0033] The first filling portion 22 and the second filling portion 42 each independently comprise a soft magnetic alloy, a thermosetting resin, and a thermoplastic resin. The surface of the soft magnetic alloy is coated with an inorganic insulating film with a thickness of less than 500 nm, which isolates the soft magnetic alloy particles, increases the insulation resistivity, and thus reduces eddy current losses. The density of the soft magnetic alloy in the first filling portion 22 and the second filling portion 42 is >4.0 g / mm³. 3 .

[0034] To further improve the curing efficiency of the above layers during the curing process, thereby improving the product properties, it is preferable that the materials of the first filling part 22 and the second filling part 42 also include a curing agent and an accelerator; preferably, the curing agent is one or more of m-phenylenediamine, isoflurane diamine, diethyltoluene diamine, or dicyandiamide; preferably, the accelerator is one or more of 2-methylimidazole, 2-ethyl-4-methylimidazole, or salicylic acid. More preferably, the content of the curing agent is 0.3-1% of the weight of the soft magnetic alloy powder particles, and the content of the accelerator is 0.1-0.3% of the weight of the soft magnetic alloy powder particles.

[0035] In a preferred embodiment, the thicknesses of the first coil layer 20 and the second coil layer 40 are each independently 20–100 μm. The thickness of the coil layer is determined based on the inductance performance, which can be selected by those skilled in the art according to their own product requirements, and will not be elaborated here. In the thin-film inductor structure of the present invention, the specific arrangement of the filling portion and electrode coil in the first and second coil layers is also based on satisfying the conventional use of inductance performance.

[0036] In a preferred embodiment, the thicknesses of the first substrate layer 10 and the second substrate layer 50 are each independently 50–200 μm. The first substrate layer 10 and the second substrate layer 50 each independently comprise a soft magnetic alloy, a thermosetting resin, and a thermoplastic resin. The surface of the soft magnetic alloy particles is coated with an inorganic insulating film with a thickness of less than 500 nm, which isolates the soft magnetic alloy particles, increases the insulation resistivity, and thus reduces eddy current losses. The density of the soft magnetic alloy particles in the first substrate layer 10 and the second substrate layer 50 is >4.0 g / mm². 3 The structure, by weight, comprises: 90-95 wt% soft magnetic alloy powder particles as the main structural framework, and 5-10 wt% organic additives filling the gaps between the alloy powder particles. The particle size of the soft magnetic alloy powder particles is 5-15 μm (D90). The organic additives include any one of thermosetting resins such as bisphenol A type epoxy resin and bisphenol F type epoxy resin; any one of thermoplastic resins such as polymethyl methacrylate and polyvinyl butyral; any one of curing agents such as m-phenylenediamine, isoflurane diamine, diethyltoluene diamine, or dicyandiamide; and any one or more curing accelerators such as 2-methylimidazole, 2-ethyl-4-methylimidazole, or salicylic acid. Preferably, the content of the curing agent is 0.3-1% of the weight of the soft magnetic alloy powder particles, and the content of the curing accelerator is 0.1-0.3% of the weight of the soft magnetic alloy powder particles.

[0037] In a preferred embodiment, the first and second filling portions are made of the same material as the first and second substrate layers, the only difference being that the soft magnetic alloy used in the filling portions can have a slightly smaller particle size than that in the substrate layers. Based on this, the bonding strength between the coil layer and the substrate layer, as well as the strength characteristics of the product, are improved.

[0038] In a preferred embodiment, the insulating layer 30 is made of polyimide film, polyester film, fluorocarbon film, or aromatic polyamide paper; preferably, the thickness of the insulating layer 30 is 13–25 μm. This is something that those skilled in the art can choose according to their own product needs, and will not be elaborated further here.

[0039] To further enhance the bonding effect between the insulation layer and each coil layer, preferably, as follows: Figure 1As shown, the thin-film inductor structure also includes an adhesive layer 60 with a thickness of 10-15 μm. The adhesive layer 60 is disposed between the first coil layer 20 and the insulating layer 30, and between the second coil layer 40 and the insulating layer 30. Preferably, the adhesive layer is made of one of epoxy resin, acrylate resin, phenolic modified polyvinyl butyral resin, polyester resin, and polyimide resin.

[0040] The present invention also provides a method for fabricating the above-mentioned thin-film inductor structure. The method includes the following steps: fabricating a coil layer, the coil layer including a first coil layer 20, an insulating layer 30, and a second coil layer 40, the first coil layer 20 including a first electrode coil 21 and a first filling portion 22, and the second coil layer 40 including a second electrode coil 41 and a second filling portion 42; placing a first substrate layer 10 on the side of the first coil layer 20 away from the insulating layer 30, placing a second substrate layer 50 on the side of the second coil layer 40 away from the insulating layer 30, and hot-pressing to obtain a thin-film inductor structure; wherein, the first substrate layer 10... The plate layer 10 has a first surface, and the first surface is divided into a first region and a second region; a first electrode coil 21 is disposed in the first region, and a first filler portion 22 is disposed in at least a portion of the second region; the surface of the insulating layer 30 away from the first substrate layer 10 is divided into a third region and a fourth region, and the vertical projection of the third region on the first surface completely coincides with the first region; a second electrode coil 41 is disposed in the third region, and a second filler portion 42 is disposed in at least a portion of the fourth region; the materials of the first filler portion 22 and the second filler portion 42 each independently include a soft magnetic alloy, a thermosetting resin and a thermoplastic resin.

[0041] Based on the reasons stated above, firstly, this invention, through the specific arrangement of the filling portion and electrode coil in the first and second coil layers, more effectively avoids the problem of thickness difference between the coil layer and the substrate layer caused by excessive electrode coil thickness. This significantly improves the interlayer bonding between the substrate magnetic sheet and the coil layer during subsequent lamination, resulting in better adhesion and preventing cracking or even severe delamination of the thin-film inductor during subsequent cutting. Secondly, this invention uses thermoplastic and thermosetting resins in combination to form the first filling portion 22 and the second filling portion 42. On the one hand, this further improves the adhesion between the substrate magnetic sheet and the coil layer during subsequent lamination. On the other hand, it also increases the strength of the product, making it less prone to deformation. The thin-film inductor of this invention does not require high-temperature sintering. After sufficient curing at 180–220°C in subsequent processes, it possesses magnetic strength comparable to that of multilayer power inductors produced by conventional LTCC process through high-temperature sintering, meeting the stringent operating environment of power inductors up to 160°C.

[0042] Preferably, the coil layer structure is as follows: Figure 2As shown, the steps for fabricating the coil layer include: adhering the first electrode coil 21 and the second electrode coil 41 to opposite side surfaces of the insulating layer 30 using an adhesive layer 60 to form a pre-coil; placing the material of the first filling portion 22 at the desired location on the insulating layer 30, extending its height 3-5 μm beyond the first electrode coil; placing the material of the second filling portion 42 at the desired location on the insulating layer 30, extending its height 3-5 μm beyond the second electrode coil; obtaining the coil to be pressed; and performing a first hot-pressing treatment on the coil to be pressed to form the coil layer. Thus, after the first hot-pressing treatment, the surface of the first electrode coil and the first filling portion away from the first substrate layer are flush; the surfaces of the second electrode coil and the second filling portion away from the first substrate layer are also flush. Preferably, in the first hot-pressing treatment step, the operating temperature is 65-80°C, the operating pressure is 2-8 MPa, and the operating time is 5-10 min. Based on this, the adhesive properties of the thermoplastic resin can be further utilized, thereby further strengthening the bonding force between the coil layer and the substrate layer.

[0043] Preferably, the hot-pressing process for preparing the thin-film inductor structure includes: sequentially performing a second hot-pressing treatment and an isostatic pressing treatment on the placed first substrate layer 10, coil layer, and second substrate layer 50 to obtain the thin-film inductor structure; to further improve the surface flatness and interlayer tightness of the product after lamination, thereby improving the product strength, preferably, during the second hot-pressing treatment, the operating temperature is 100-150℃, the operating pressure is 15-20MPa, and the operating time is 10-15min; to further improve the performance uniformity of the product, preferably, during the isostatic pressing treatment, the operating temperature is 60-80℃, the operating pressure is 40-60MPa, and the operating time is 10-25min.

[0044] Specifically, a first sheet with the same material composition as the first filling part 22 and a second sheet with the same material composition as the second filling part 42 are first provided. A laser engraving machine is used to remove material from the sheets corresponding to the positions of the first electrode coil 21 and the second electrode coil 41, while simultaneously marking the alignment points required for CCD alignment during lamination. Then, a hot press is used to laminate each filling part and each electrode coil. To further improve the flush characteristics of each filling part and each electrode coil in the subsequent finished product, the original thickness of each filling part is preferably 3-5 μm greater than the thickness of each electrode coil line. Next, a hot press is used to laminate the first substrate layer 10, the first coil layer 20, the insulating layer 30, the second coil layer 40, and the second substrate layer 50. Finally, the intermediate product after lamination is placed in a plastic bag for vacuum sealing and then placed in an isostatic press for isostatic pressing. Isostatic pressing applies equal pressure to all aspects of a product using a liquid medium. In this step, the thermoplastic resin softens, facilitating particle movement and rearrangement, thereby making the product more compact.

[0045] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0046] Example 1

[0047] A thin-film inductor with model number 121003 (size 1.2×1.0×0.3mm) is manufactured. A schematic diagram of its product structure is shown below. Figure 1 As shown, the thickness of the first substrate layer is 73-76 μm; the thickness of the first coil layer is 60 μm; the thickness of the insulating layer (material is polyimide film) is 13 μm; the thickness of the second coil layer is 60 μm; the thickness of the second substrate layer is 73-76 μm; and the thickness of the adhesive layer (material is acrylic resin) is 3 μm.

[0048] Its preparation process is as follows:

[0049] The engraving process for the filling section is as follows: Take two pre-cut magnetic sheets with a thickness of 63μm (each sheet has a 100μm thick PET film attached). Use a laser engraving machine to remove material from designated locations on the magnetic sheets without piercing the PET film. The patterns of the material-removed portions on the two magnetic sheets should match the patterns of the first and second electrode coils, respectively. Simultaneously, mark the alignment points required for CCD alignment during pressing. This yields the materials for the first and second filling sections. The materials for each section independently comprise 91 parts of a soft magnetic alloy (D50 is 5μm iron-silicon-chromium, passivated with phosphoric acid), 5.45 parts of thermosetting resin (E51 epoxy resin), 2.9 parts of thermoplastic resin (acrylic resin), 0.5 parts of curing agent (2-ethyltoluenediamine), and 0.15 parts of accelerator (salicylic acid).

[0050] Coil layer fabrication steps: First, the first and second electrode coils are adhered to opposite sides of the insulating layer using an adhesive layer to form a pre-filled coil. The material for the first filler portion is placed in the insulating layer at the desired location for the first filler portion, extending 3 μm beyond the first electrode coil. The material for the second filler portion is placed in the insulating layer at the desired location for the second filler portion, extending 3 μm beyond the second electrode coil. This yields the coil to be pressed. The coil to be pressed undergoes a first hot-pressing treatment to form the coil layer. The PET film attached to the first and second filler magnetic sheets is peeled off. A schematic diagram of the resulting coil layer is shown below. Figure 2 As shown. The hot-pressing temperature is controlled at 70±3℃, the pressure at 5±1MPa, and the time at 8 minutes. After the first hot-pressing treatment, the first electrode coil is flush with the surface of the first filling portion away from the first substrate layer; the second electrode coil and the surface of the second filling portion away from the first substrate layer are also flush.

[0051] The second hot-pressing step: Two 80μm thick substrate magnetic sheets (with identical material composition and filling) are neatly placed on the upper and lower surfaces of the already filled coil layer, and a second hot-pressing process is performed using a hot press. The hot-pressing temperature is controlled at 150℃, the pressure at 18MPa, and the time is 15min.

[0052] Isostatic pressing step: After two hot pressing treatments, the intermediate product is placed into a plastic sealing bag for vacuum sealing, and then placed in an isostatic press for isostatic pressing treatment. The isostatic pressing pressure is 50MPa, the temperature is 80℃, and the holding time is 20min.

[0053] Cutting steps: After isostatic pressing, the pressed semi-finished product is cut into individual products using a cutting machine, and then placed in an oven for high-temperature curing at 220℃ for 2.5 hours.

[0054] Example 2

[0055] The only difference from Example 1 is:

[0056] In the engraving step of the filling part: the thickness of the magnetic sheet is 40μm.

[0057] In the coil layer fabrication process: the hot pressing temperature is controlled at 75±3℃, the pressure is controlled at 8±1MPa, and the time is 5min. The material of the first filling part is placed in the insulating layer at the position where the first filling part is to be formed, and its height is 20μm lower than the first electrode coil; the material of the second filling part is placed in the insulating layer at the position where the second filling part is to be formed, and its height is 20μm lower than the second electrode coil.

[0058] In the second hot pressing step: the hot pressing temperature is controlled at 120℃, the pressure is controlled at 20MPa, and the time is 10min.

[0059] During the isostatic pressing step: the temperature is 70℃ and the holding time is 25min.

[0060] During the cutting process: curing temperature 200℃, heat preservation time 3 hours.

[0061] Example 3

[0062] The only difference from Example 1 is:

[0063] In the engraving process of the filling part: the thickness of the magnetic sheet is 25μm.

[0064] In the coil layer fabrication process: the hot pressing temperature is controlled at 70±3℃, the pressure is controlled at 8±1MPa, and the time is 7min. The material of the first filling part is placed in the insulating layer at the position where the first filling part is to be formed, and its height is 35μm lower than the first electrode coil; the material of the second filling part is placed in the insulating layer at the position where the second filling part is to be formed, and its height is 35μm lower than the second electrode coil.

[0065] In the second hot pressing step: the hot pressing temperature is controlled at 140℃, the pressure is controlled at 20MPa, and the time is 10min.

[0066] During the isostatic pressing step: the temperature is 75℃ and the holding time is 22min.

[0067] During the cutting process: curing temperature 200℃, heat preservation time 3 hours.

[0068] Example 4

[0069] A thin-film inductor with model number 121003 (size 1.2×1.0×0.4mm) is manufactured, wherein the thickness of the first substrate layer is 70-73μm; the thickness of the first coil layer is 90μm; the thickness of the insulating layer (material is polyester film) is 25μm; the thickness of the second coil layer is 90μm; the thickness of the second substrate layer is 70-73μm; and the thickness of the adhesive layer (material is polyvinyl butyral) is 4μm.

[0070] Its preparation process is as follows:

[0071] The engraving process for the filling section is as follows: Take two pre-cut magnetic sheets with a thickness of 93μm (each sheet has a 100μm thick PET film attached). Use a laser engraving machine to remove material from designated locations on the magnetic sheets, without piercing the PET film. The patterns of the material-removed portions on the two magnetic sheets are consistent with the patterns of the first and second electrode coils, respectively. Simultaneously, the alignment marks required for CCD alignment during pressing are marked out, resulting in the materials for the first and second filling sections. The materials for the first and second filling sections each independently comprise 94 parts of a soft magnetic alloy (D50 is 5μm iron-silicon-chromium, passivated with phosphate coating), 4 parts of thermosetting resin (epoxy-modified silicone resin), and 2 parts of thermoplastic resin (acrylic resin).

[0072] Coil layer fabrication steps: First and second electrode coils are adhered to opposite sides of the insulating layer using an adhesive layer to form a pre-filled coil; material for the first filler portion is placed in the insulating layer at the desired location for the first filler portion, extending 3 μm beyond the first electrode coil; material for the second filler portion is placed in the insulating layer at the desired location for the second filler portion, extending 3 μm beyond the second electrode coil; this yields the coil to be pressed; the coil to be pressed undergoes a first hot-pressing process to form the coil layer; the PET film attached to the first and second filler magnetic sheets is peeled off. The hot-pressing temperature is controlled at 75±3℃, the pressure at 3±1MPa, and the time at 10 min. After the first hot-pressing process, the first electrode coil and the surface of the first filler portion away from the first substrate layer are flush; the surfaces of the second electrode coil and the second filler portion away from the first substrate layer are also flush.

[0073] The second hot-pressing step: Two 75μm thick substrate magnetic sheets (with identical material composition and filling) are neatly placed on the upper and lower surfaces of the already filled coil layer, and a second hot-pressing process is performed using a hot press. The hot-pressing temperature is controlled at 150℃, the pressure at 15MPa, and the time is 10min.

[0074] Isostatic pressing step: After two hot pressing treatments, the intermediate product is placed into a plastic sealing bag for vacuum sealing, and then placed in an isostatic press for isostatic pressing treatment. The isostatic pressing pressure is 60MPa, the temperature is 78℃, and the holding time is 15min.

[0075] Cutting steps: After isostatic pressing, the pressed semi-finished product is cut into individual products using a cutting machine, and then placed in an oven for high-temperature curing at 200℃ for 1.5 hours.

[0076] Example 5

[0077] A thin-film inductor with model number 201208 (size 2.0×1.2×0.7mm) is manufactured, wherein the thickness of the first substrate layer is 183-186μm; the thickness of the first coil layer is 100μm; the thickness of the insulating layer (material is polyimide) is 20μm; the thickness of the second coil layer is 100μm; the thickness of the second substrate layer is 183-186μm; and the thickness of the adhesive layer (material is polyurethane) is 5μm.

[0078] Its preparation process is as follows:

[0079] The engraving process for the filling section is as follows: Take two pre-cut magnetic sheets with a thickness of 105μm (each sheet has a 100μm thick PET film attached). Use a laser engraving machine to remove material from designated locations on the magnetic sheets without piercing the PET film. The patterns of the material-removed portions on the two magnetic sheets should match the patterns of the first and second electrode coils, respectively. Simultaneously, mark the alignment points required for CCD alignment during pressing. This yields the materials for the first and second filling sections. The materials for each section independently comprise 90 parts of a soft magnetic alloy (D50 is a 5μm amorphous alloy, passivated with phosphate), 5.7 parts of thermosetting resin (epoxy resin), 4 parts of thermoplastic resin (polyvinyl butyral resin), 0.21 parts of curing agent (m-phenylenediamine), and 0.09 parts of accelerator (2-methylimidazole).

[0080] Coil layer fabrication steps: First and second electrode coils are adhered to opposite sides of the insulating layer using an adhesive layer to form a pre-filled coil; material for the first filler portion is placed in the insulating layer at the desired location for the first filler portion, extending 5 μm beyond the first electrode coil; material for the second filler portion is placed in the insulating layer at the desired location for the second filler portion, extending 5 μm beyond the second electrode coil; this yields the coil to be pressed; the coil to be pressed undergoes a first hot-pressing process to form the coil layer; the PET film attached to the first and second filler magnetic sheets is peeled off. The hot-pressing temperature is controlled at 80±3℃, the pressure at 3±1MPa, and the time at 10 min. After the first hot-pressing process, the first electrode coil and the surface of the first filler portion away from the first substrate layer are flush; the surfaces of the second electrode coil and the second filler portion away from the first substrate layer are also flush.

[0081] The second hot-pressing step: Two 192μm thick substrate magnetic sheets (with identical material composition and filling) are neatly placed on the upper and lower surfaces of the already filled coil layer, and a second hot-pressing process is performed using a hot press. The hot-pressing temperature is controlled at 150℃, the pressure at 15MPa, and the time is 10min.

[0082] Isostatic pressing step: After two hot pressing treatments, the intermediate product is placed into a plastic sealing bag for vacuum sealing, and then placed in an isostatic press for isostatic pressing treatment. The isostatic pressing pressure is 40MPa, the temperature is 70℃, and the holding time is 25min.

[0083] Cutting steps: After isostatic pressing, the pressed semi-finished product is cut into individual products using a cutting machine, and then placed in an oven for high-temperature curing at 200℃ for 2.5 hours.

[0084] Comparative Example 1

[0085] The only difference from Example 1 is that the first filling part and the second filling part are not added.

[0086] Performance characterization:

[0087] (a) Testing the strength of a magnet

[0088] Flexural strength and drop resistance were tested separately.

[0089] The bending strength test standard refers to the reliability test standard for multilayer inductors. The test conditions are: bending 2mm, pressure rate 0.5mm / s, holding time 30s. If the magnet does not break, it is considered qualified.

[0090] Drop test conditions: The product is dropped freely from a height of 1m onto a concrete floor. If the product does not suffer obvious mechanical damage, it is considered qualified.

[0091] (II) Stratified Testing

[0092] Observe the side of the thermo-cured product under an 80x industrial microscope to check for delamination (interlayer cracking). The number of products inspected is 80 pieces, and the number of delaminations is calculated.

[0093] The performance results are shown in Table 1 below:

[0094] Table 1

[0095] Magnetic bending strength Drop test Number of delaminations / pcs Example 1 Pass Pass 0 Example 2 Pass Pass 2 Example 3 Pass Pass 16 Example 4 Pass Pass 0 Example 5 Pass Pass 0 Comparative Example 1 Pass Pass Severe delamination in the middle region when cut

[0096] As can be seen from the performance results of Examples 1 to 5 and Comparative Example 1, the thin-film inductive magnet produced by the present invention has excellent strength and no serious delamination phenomenon in the middle region during cutting.

[0097] In particular, as shown by the data from Embodiments 1 to 3, the first electrode coil is flush with the surface of the first filling portion away from the first substrate layer; the second electrode coil and the second filling portion are also flush with the surfaces of the second electrode coil away from the first substrate layer. Furthermore, the area where the first electrode coil contacts the first surface completely overlaps with the first region, and the first filling portion is disposed throughout the entire second region; the area where the second electrode coil contacts the insulating layer surface completely overlaps with the third region, and the second filling portion is disposed throughout the entire fourth region. Based on this, inductor delamination can be more effectively avoided, resulting in better interlayer bonding in the product.

[0098] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for fabricating a thin-film inductor structure, characterized in that, The preparation method includes the following steps: The first electrode coil (21) and the second electrode coil (41) are adhered to the opposite two sides of the insulating layer (30) through the adhesive layer (60) to form a pre-coil; Place the material of the first filling part (22) on the insulating layer (30) at the position where the first filling part (22) is to be formed, and make its height exceed the first electrode coil (21) by 3~5μm; place the material of the second filling part (42) on the insulating layer (30) at the position where the second filling part (42) is to be formed, and make its height exceed the second electrode coil (41) by 3~5μm; and obtain the coil to be pressed; The coil to be pressed is subjected to a first hot pressing treatment to form a first coil layer (20) and a second coil layer (40); in the first hot pressing treatment step, the operating temperature is 65~80℃, the operating pressure is 2~8MPa, and the operating time is 5~10min; The first substrate layer (10) is placed on the side of the first coil layer (20) away from the insulating layer (30), and the second substrate layer (50) is placed on the side of the second coil layer (40) away from the insulating layer (30). The thin film inductor structure is obtained by hot pressing. The thin-film inductor structure includes: The first substrate layer (10) has a first surface, and the first surface is divided into a first region and a second region; A first coil layer (20) is disposed on the first surface of the first substrate layer (10). The first coil layer (20) includes a first electrode coil (21) and a first filling portion (22). The first electrode coil (21) is disposed in the first region. The area where the first electrode coil (21) contacts the first surface completely overlaps with the first region, and the first filling portion (22) is disposed in the entire second region. The first electrode coil (21) and the surface of the first filling portion (22) away from the first substrate layer (10) are flush. An insulating layer (30) is disposed on the surface of the first coil layer (20) away from the first substrate layer (10). The surface of the insulating layer (30) away from the first substrate layer (10) is divided into a third region and a fourth region, and the vertical projection of the third region on the first surface completely coincides with the first region. A second coil layer (40) is disposed on the surface of the insulating layer (30) away from the first substrate layer (10). The second coil layer (40) includes a second electrode coil (41) and a second filling portion (42). The second electrode coil (41) is disposed in the third region. The area where the second electrode coil (41) contacts the surface of the insulating layer (30) completely overlaps with the third region, and the second filling portion (42) is disposed in the entire fourth region. The surfaces of the second electrode coil (41) and the second filling portion (42) away from the first substrate layer (10) are flush. The second substrate layer (50) is disposed on the surface of the second coil layer (40) away from the first substrate layer (10); The thin-film inductor structure further includes an adhesive layer (60), which is disposed between the first coil layer (20) and the insulating layer (30), and between the second coil layer (40) and the insulating layer (30); The materials of the first filling part (22) and the second filling part (42) by weight each independently include 90-95 parts of soft magnetic alloy, 3-6 parts of thermosetting resin and 2-4 parts of thermoplastic resin; the soft magnetic alloy is in granular form and the particle size of the soft magnetic alloy is 2-10 μm.

2. The method for preparing a thin-film inductor structure according to claim 1, characterized in that, The thermosetting resin is selected from one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, silicone resin and epoxy modified silicone resin; the thermoplastic resin is selected from polymethyl methacrylate and / or polyvinyl butyral.

3. The method for preparing a thin-film inductor structure according to claim 1, characterized in that, The insulating layer (30) is made of polyester, polyimide, fluorocarbon film or aromatic polyamide; the thickness of the insulating layer (30) is 13~25μm; The adhesive layer (60) is made of one or more of epoxy resin, acrylate resin, phenolic modified polyvinyl butyral resin, polyester resin or polyimide resin; the thickness of the adhesive layer (60) is 3~5μm.

4. The method for preparing a thin-film inductor structure according to claim 1, characterized in that, The materials of the first filling part (22) and the second filling part (42) also include curing agents and accelerators; The curing agent is one or more of m-phenylenediamine, isoflurone diamine, diethyltoluene diamine, or dicyandiamide; The accelerator is one or more of 2-methylimidazole, 2-ethyl-4-methylimidazole, or salicylic acid.

5. The method for preparing a thin-film inductor structure according to claim 1, characterized in that, The thickness of the first coil layer (20) and the second coil layer (40) is independently 20~100μm, and the thickness of the first substrate layer (10) and the second substrate layer (50) is independently 50~200μm.

6. The method for preparing a thin-film inductor structure according to claim 1, characterized in that, The steps for hot pressing to prepare the thin-film inductor structure include: The first substrate layer (10), the coil layer and the second substrate layer (50) after placement are subjected to a second hot pressing treatment and an isostatic pressing treatment in sequence to obtain the thin film inductor structure; During the second hot pressing process, the operating temperature is 100~150℃, the operating pressure is 15~20MPa, and the operating time is 10~15min; During the isostatic pressing process, the operating temperature is 60~80℃, the operating pressure is 40~60MPa, and the operating time is 10~25min.

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