Embedded magnetic core assembly, transformer and circuit board

Abstract

The embodiment of the present application provides an embedded magnetic core assembly, a transformer and a circuit board, the embedded magnetic core assembly comprises a first dielectric layer, a bonding layer, a second dielectric layer and a ring-shaped magnetic core which are stacked in sequence; the first dielectric layer is provided with a first ring-shaped blind groove, the bonding layer is provided with a ring-shaped through groove, the second dielectric layer is provided with a second ring-shaped blind groove, and the first ring-shaped blind groove, the ring-shaped through groove and the second ring-shaped blind groove are communicated with each other; the ring-shaped magnetic core is arranged in the first ring-shaped blind groove, the ring-shaped through groove and the second ring-shaped blind groove, and the bonding layer is bonded to the periphery of the ring-shaped magnetic core to fix the ring-shaped magnetic core. The embedded magnetic core assembly of the embodiment of the present application can bury the magnetic core into the first dielectric layer and the second dielectric layer, and the bonding layer is bonded to the periphery of the magnetic core, so that the magnetic core can be fixed through the bonding layer, the fixation of the magnetic core is realized, the magnetic core is prevented from shaking, and therefore the integration and performance of the PCB using the embedded magnetic core assembly can be improved.

Description

Technical Field

[0001] This application relates to the field of circuit board technology, and in particular to an embedded magnetic core assembly, a transformer, and a circuit board. Background Technology

[0002] Traditional magnetic core devices or components in the industry are made by winding enameled wire around a magnetic core or other magnetic material. However, the integration and isolation performance of enameled wire winding are relatively poor. Therefore, a method of embedding magnetic cores and other magnetic materials inside PCBs has gradually emerged. PCB-embedded magnetic components offer high integration and good isolation performance.

[0003] The main disadvantage of embedding magnetic cores or magnetic materials inside a PCB is that the embedded magnetic cores or other magnetic materials cannot be fixed inside the PCB. There are several reasons for this: First, magnetic cores and other magnetic materials are fragile, and direct pressing during processing will cause the magnetic core to break and be damaged. Second, the performance of magnetic core materials is greatly affected by external stress and is sensitive to stress. For example, parameters such as the permeability of the magnetic core are very sensitive to stress, and the inductance of the magnetic core will drop sharply under stress.

[0004] If the magnetic cores and other magnetic materials embedded inside the PCB are not fixed, they will move around freely during transportation and use. Under the influence of environmental vibration and impact, the magnetic cores and other magnetic materials will be damaged and broken, resulting in substandard product performance. Utility Model Content

[0005] This application provides an embedded magnetic core assembly, a transformer, and a circuit board, which can embed the magnetic core into a first dielectric layer and a second dielectric layer, and fix the magnetic core through an adhesive layer, thereby improving the integration and performance of the PCB using the embedded magnetic core assembly.

[0006] This application provides an embedded magnetic core assembly, including a first dielectric layer, an adhesive layer, a second dielectric layer, and a toroidal magnetic core stacked sequentially. The first dielectric layer is provided with a first annular blind groove, the adhesive layer is provided with an annular through groove, and the second dielectric layer is provided with a second annular blind groove. The first annular blind groove, the annular through groove, and the second annular blind groove are interconnected. The annular magnetic core is disposed in the first annular blind slot, the annular through slot, and the second annular blind slot, and the adhesive layer is bonded to the periphery of the annular magnetic core to fix the annular magnetic core.

[0007] In some embodiments, the adhesive layer is located within the first annular blind groove and / or the second annular blind groove, and is bonded to the sidewall of the annular magnetic core.

[0008] In some embodiments, the adhesive layer is located on the bottom wall of the first annular blind groove and / or the bottom wall of the second annular blind groove, and is bonded to the bottom wall and the side wall of the annular magnetic core.

[0009] In some embodiments, the first medium layer is provided with a first venting groove, and the first venting groove is connected to the first annular blind groove. The adhesive layer is provided with a venting groove, which is connected to the annular groove. The second medium layer is provided with a second venting groove, which is connected to the second annular blind groove; The first exhaust duct and / or the second exhaust duct are connected to the outside.

[0010] In some embodiments, the bottom wall of the first exhaust channel is provided with a first exhaust hole, the first exhaust hole connecting the first exhaust channel to the outside; and / or The bottom wall of the second exhaust groove is provided with a second exhaust hole, which connects the second exhaust groove to the outside.

[0011] In some embodiments, the height between the bottom wall of the first annular blind groove and the bottom wall of the second annular blind groove is H, and the thickness of the annular magnetic core is C, wherein H is greater than C.

[0012] In some embodiments, the distance between the dielectric layer and the bottom wall of the second annular blind groove is D, where 0.1H <D<0.9H。

[0013] In some embodiments, the widths of the first annular blind slot, the annular through slot, and the second annular blind slot are greater than the width of the annular magnetic core.

[0014] This application also provides a transformer, including: The embedded magnetic core assembly described in any of the above claims; A first metal layer is disposed on the side of the first dielectric layer away from the adhesive layer, and a plurality of first traces and a plurality of second traces spaced apart from each other are disposed on the first metal layer; A second metal layer is disposed on the side of the second dielectric layer away from the adhesive layer, and multiple third traces and multiple fourth traces are disposed on the second metal layer at intervals between them; The plurality of first traces and the plurality of third traces are connected in series and wound around the annular magnetic core to form a primary coil. The multiple second traces and the multiple fourth traces are connected in series and wound around the annular magnetic core to form a secondary coil.

[0015] This application also provides a circuit board including the above-described transformer.

[0016] The embedded magnetic core assembly of this application embodiment can embed the magnetic core into the first dielectric layer and the second dielectric layer, and the adhesive layer is bonded to the periphery of the magnetic core. Therefore, the magnetic core can be fixed by the adhesive layer, and the magnetic core can be fixed to prevent the magnetic core from shaking. Thus, the integration and performance of the PCB using this embedded magnetic core assembly can be improved. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the embedded magnetic core assembly according to an embodiment of this application.

[0019] Figure 2 for Figure 1 The diagram shows the structure of the first dielectric layer of the embedded magnetic core assembly.

[0020] Figure 3 for Figure 1 The diagram shows the structure of the first dielectric layer and the adhesive layer of the embedded magnetic core assembly.

[0021] Figure 4 for Figure 1 The diagram shows a partial exploded view of the embedded magnetic core assembly.

[0022] Figure 5 for Figure 1 The diagram shows the internal structure of the embedded magnetic core assembly.

[0023] Figure 6 for Figure 1 An internal perspective view of the embedded magnetic core assembly shown.

[0024] Figure 7 This is a schematic diagram of the transformer structure according to an embodiment of this application.

[0025] Figure 8 for Figure 7 The diagram shows the internal winding of the transformer. Detailed Implementation

[0026] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0027] This application provides an embedded magnetic core assembly that can embed the magnetic core into the dielectric layer of a PCB and fix the magnetic core, thereby improving the integration and performance of the PCB.

[0028] refer to Figures 1 to 4 , Figure 1 This is a schematic diagram of the embedded magnetic core assembly according to an embodiment of this application. Figure 2 for Figure 1 The diagram shows the structure of the first dielectric layer of the embedded magnetic core assembly. Figure 3 for Figure 1 The diagram shows the structure of the first dielectric layer and the adhesive layer of the embedded magnetic core assembly. Figure 4 for Figure 1 The diagram shows a partial exploded view of the embedded magnetic core assembly.

[0029] The embedded magnetic core assembly 100 includes a first dielectric layer 10, an adhesive layer 20, a second dielectric layer 30, and a toroidal magnetic core 40.

[0030] The first dielectric layer 10, the adhesive layer 20, and the second dielectric layer 30 are stacked sequentially, as follows: Figure 1 As shown. In practical applications, the first dielectric layer 10 and the second dielectric layer 30 can both be made of FR-4 (glass fiber and epoxy resin), and the adhesive layer 20 can be made of resin-based pure glue, resin-containing prepreg (PP), or adhesive, etc. The adhesive layer 20 is cured at room temperature and softens or flows at temperatures between 100°C and 200°C. In some embodiments, the toroidal magnetic core 40 can be made of ferrite.

[0031] The first dielectric layer 10 is provided with a first annular blind groove 11, such as Figure 2 As shown. The adhesive layer 20 is provided with an annular through groove 21, as... Figure 3 As shown. The second dielectric layer 30 is provided with a second annular blind groove 31, as... Figure 4 As shown. In practical applications, the first annular blind groove 11, the annular through groove 21, and the second annular blind groove 31 can be formed by mechanical cutting or laser engraving. The first annular blind groove 11, the annular through groove 21, and the second annular blind groove 31 are positioned opposite each other so that they are interconnected and form a cavity.

[0032] Understandably, in practical applications, the first dielectric layer 10 and the second dielectric layer 30 are relatively thick and can be directly processed, while the adhesive layer 20 is relatively thin and inconvenient to process directly on the adhesive layer 20. Therefore, the adhesive layer 20 can be pasted onto the first dielectric layer 10 (or the second dielectric layer 30), and then the first dielectric layer 10 and the adhesive layer 20 (or the second dielectric layer 30 and the adhesive layer 20) can be mechanically cut or laser-etched together to form the required annular blind groove and an annular through groove on the adhesive layer 20.

[0033] The annular magnetic core 40 is disposed within the first annular blind slot 11, the annular through slot 21, and the second annular blind slot 31, i.e., within the aforementioned cavity. The annular magnetic core 40 is partially located within the first annular blind slot 11, partially within the second annular blind slot 31, and extends through the annular through slot 21. An adhesive layer 20 is bonded to the periphery of the annular magnetic core 40, for example, to the sidewall of the annular magnetic core 40, to fix the annular magnetic core 40.

[0034] In practical applications, the first annular blind groove 11, the annular through groove 21, and the second annular blind groove 31 can be fabricated separately. Then, the annular magnetic core 40 is placed in the first annular blind groove 11, and the adhesive layer 20 and the second dielectric layer 30 are stacked in sequence (if the adhesive layer 20 and the first dielectric layer 10 are fabricated together to form the first annular blind groove 11 and the annular through groove 21, then the adhesive layer 20 does not need to be stacked). Subsequently, the three are pressed together under a certain temperature and pressure, so that the first dielectric layer 10, the adhesive layer 20, and the second dielectric layer 30 are bonded together, and the adhesive layer 20 fixes the annular magnetic core 40.

[0035] In some embodiments, the adhesive layer 20 may partially flow into the first annular blind groove 11, or partially flow into the second annular blind groove 31, or partially flow into the first annular blind groove 11 and partially flow into the second annular blind groove 31, that is, partially located in the first annular blind groove 11 and / or the second annular blind groove 31, and bonded to the sidewall of the annular magnetic core 40 to fix the annular magnetic core 40.

[0036] For example, during the pressing process, temperature and pressure can be controlled to allow the resin in the adhesive layer 20 (e.g., pure resin adhesive or resin-containing prepreg PP) to flow and partially fill the first annular blind groove 11 and / or the second annular blind groove 31, that is, to fill the periphery of the annular magnetic core 40. After the resin cools and cures, it can be bonded to the periphery of the annular magnetic core 40, thereby fixing the annular magnetic core 40.

[0037] In some embodiments, the adhesive layer 20 may be partially located on the bottom wall of the first annular blind groove 11 and / or the bottom wall of the second annular blind groove 31, and bonded to the bottom wall and the side wall of the annular magnetic core 40. For example, temperature and pressure can be controlled during the pressing process to increase the resin fluidity of the adhesive layer 20, allowing it to partially flow to the bottom wall of the first annular blind groove 11 and / or the bottom wall of the second annular blind groove 31. After the resin cools and cures, it can be bonded to the bottom wall of the blind groove and the side wall of the annular magnetic core 40. It is understood that the adhesive layer 20 being partially located on the bottom wall of the first annular blind groove 11 and / or the bottom wall of the second annular blind groove 31 can increase the bonding area between the adhesive layer 20 and the side wall of the annular magnetic core 40, increase the bonding force between them, and improve the fixing effect on the annular magnetic core 40.

[0038] The embedded magnetic core assembly 100 of this application embodiment can embed the magnetic core 40 into the first dielectric layer 10 and the second dielectric layer 30, so that the adhesive layer 20 is bonded to the periphery of the magnetic core 40. Therefore, the magnetic core 40 can be fixed by the adhesive layer 20, thereby fixing the magnetic core 40 and preventing the magnetic core 40 from shaking. Thus, the integration and performance of the PCB using the embedded magnetic core assembly 100 can be improved.

[0039] In some embodiments, an exhaust groove can be provided in the embedded magnetic core assembly 100 to connect the cavity inside the embedded magnetic core assembly 100 with the outside, maintain a constant air pressure inside the cavity, and avoid stress on the toroidal magnetic core 40 due to air pressure changes, which would affect the performance of the toroidal magnetic core 40.

[0040] Among them, such as Figure 2 As shown, the first dielectric layer 10 is provided with a first venting groove 12, which communicates with the first annular blind groove 11. Figure 3 As shown, the adhesive layer 20 is provided with a venting groove 22, which communicates with the annular groove 21. Figure 4 As shown, the second medium layer 30 is provided with a second exhaust groove 32, which is connected to the second annular blind groove 31.

[0041] It is understandable that the first exhaust groove 12, the exhaust through groove 22, and the second exhaust groove 32 can form an integral exhaust groove, and are connected to the cavity formed by the first annular blind groove 11, the annular through groove 21, and the second annular blind groove 31.

[0042] The first exhaust groove 12 can be configured to communicate with the outside, or the second exhaust groove 32 can be configured to communicate with the outside, or both the first exhaust groove 12 and the second exhaust groove 32 can be configured to communicate with the outside. Thus, through the design of the exhaust grooves, the cavity formed by the interconnected first annular blind groove 11, annular through groove 21, and second annular blind groove 31 can be connected to the outside. When the embedded magnetic core assembly 100 undergoes thermal expansion and contraction, the air pressure inside the cavity will change. Because the cavity is connected to the outside, when the air pressure inside the cavity changes, air can be vented or drawn in through the exhaust grooves, ensuring a constant air pressure inside the cavity and preventing the magnetic core 40 from being affected by changes in air pressure inside the cavity, thereby improving the performance of the PCB using this embedded magnetic core assembly 100.

[0043] In some embodiments, reference Figure 5 , Figure 5 for Figure 1 The diagram shows the internal structure of the embedded magnetic core assembly. The bottom wall of the first venting groove 12 has a first venting hole 13, which connects the first venting groove 12 to the outside. This allows the first venting groove 12 to communicate with the outside.

[0044] In some embodiments, a second exhaust hole may be provided on the bottom wall of the second exhaust groove 32, and the second exhaust hole connects the second exhaust groove 32 with the outside. Thus, the second exhaust groove 32 can be connected to the outside.

[0045] Understandably, in some embodiments, a first exhaust port 13 and a second exhaust port can be provided simultaneously. The first exhaust port 13 connects the first exhaust groove 12 to the outside, and the second exhaust port connects the second exhaust groove 32 to the outside. Thus, it is possible to achieve simultaneous communication between the first exhaust groove 12 and the second exhaust groove 32 and the outside.

[0046] In some embodiments, such as Figure 5 As shown, the width of the first annular blind slot 11 is A, and the width of the annular magnetic core 40 is B. The width of the annular blind slot is its annular width, and the width of the annular magnetic core is also its annular width. Specifically, the width A of the first annular blind slot 11 is greater than the width B of the annular magnetic core 40. For example, in some embodiments, AB ≥ 0.1 mm. It is understood that setting the width A of the first annular blind slot 11 to be greater than the width B of the annular magnetic core 40 ensures a gap between the slot wall of the first annular blind slot 11 and the side wall of the annular magnetic core 40, preventing the annular magnetic core 40 from being squeezed by the slot wall and thus generating stress, thereby ensuring the performance of the annular magnetic core 40.

[0047] In practical applications, the width of the annular through groove 21 and the second annular blind groove 31 may be the same as the width of the first annular blind groove 11, that is, the widths of the first annular blind groove 11, the annular through groove 21, and the second annular blind groove 31 are all greater than the width B of the annular magnetic core 40, so as to ensure that gaps exist at all positions on the side wall of the annular magnetic core 40, and prevent all positions on the side wall of the annular magnetic core 40 from being squeezed by the groove walls.

[0048] In some embodiments, refer to Figure 6 , Figure 6 is Figure 1 an internal perspective view of the illustrated embedded magnetic core assembly. The height between the bottom wall of the first annular blind groove 11 and the bottom wall of the second annular blind groove 31 is H, that is, the height of the cavity formed by the mutual communication of the first annular blind groove 11, the annular through groove 21, and the second annular blind groove 31 is H. The thickness of the annular magnetic core 40 is C. The height H is greater than the thickness C of the annular magnetic core 40. For example, in some embodiments, H-C≥0.1mm.

[0049] It can be understood that the height H of the cavity is greater than the thickness C of the annular magnetic core 40, which can ensure that there is a gap at the top of the annular magnetic core 40, so that neither the top nor the bottom of the annular magnetic core 40 is squeezed by the bottom walls of the blind grooves, avoiding stress generated by squeezing on the top and bottom of the annular magnetic core 40, and thus the performance of the annular magnetic core 40 can be guaranteed.

[0050] In some embodiments, as shown in Figure 6 , the distance between the dielectric layer 20 and the bottom wall of the second annular blind groove 31 is D, where 0.1H<D<0.9H. The distance D between the dielectric layer 20 and the bottom wall of the second annular blind groove 31 can be understood as the distance between the center of the dielectric layer 20 and the bottom wall of the second annular blind groove 31.

[0051] The embodiments of the present application further provide a transformer, which may be an embedded isolation transformer. Reference is made to Figure 7 and Figure 8 , Figure 7 which is a schematic structural diagram of a transformer according to an embodiment of the present application, Figure 8 is Figure 7 a schematic diagram of the internal winding of the illustrated transformer. The transformer 200 includes an embedded magnetic core assembly 100, a first metal layer 210, and a second metal layer 220.

[0052] The embedded magnetic core assembly 100 is the embedded magnetic core assembly according to any one of the foregoing embodiments. The first metal layer 210 is disposed on the side of the first dielectric layer 10 facing away from the adhesive layer 20. The second metal layer 220 is disposed on the side of the second dielectric layer 30 facing away from the adhesive layer 20. In practical applications, both the first metal layer 210 and the second metal layer 220 may be copper layers.

[0053] As shown in Figure 8 As shown, a plurality of first traces 211 and a plurality of second traces 212 spaced apart from each other are provided on the first metal layer 210, and a plurality of third traces 221 and a plurality of fourth traces 222 spaced apart from each other are provided on the second metal layer 220. In practical applications, the first traces 211, second traces 212, third traces 221, and fourth traces 222 can be formed by etching on the copper layer.

[0054] Multiple first traces 211 and multiple third traces 221 are connected in series and wound around the toroidal magnetic core 40 to form the primary winding of the transformer. Multiple second traces 212 and multiple fourth traces 222 are connected in series and wound around the toroidal magnetic core 40 to form the secondary winding of the transformer.

[0055] In practical applications, the first trace 211 and the third trace 221 can be connected in series through the first via 231, and the second trace 212 and the fourth trace 222 can be connected in series through the second via 232. Both the first via 231 and the second via 232 penetrate the first dielectric layer 10, the adhesive layer 20, and the second dielectric layer 30. The first via 231 and the second via 232 can be formed by drilling and electroplating. The number and location of the first via 231 and the second via 232 can be set according to actual requirements.

[0056] With the above structural configuration, an embedded isolation transformer can be realized. The transformer core 40 is embedded in the dielectric layer of the PCB, and the transformer winding is formed by the lines on the metal layer of the PCB. The transformer of this embodiment has the advantages of high integration and good isolation performance.

[0057] This application embodiment also provides a circuit board, including the transformer 200 described above. In practical applications, various circuits connected to the transformer 200 can also be disposed on the circuit board.

[0058] In the description of this application, it should be understood that terms such as “first” and “second” are used only to distinguish similar objects and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0059] It should be noted that in the embodiments of this application, "connection" can be understood as electrical connection. The connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be a direct connection between A and B, or an indirect connection between A and B through one or more other electrical components.

[0060] The embedded magnetic core assembly, transformer, and circuit board provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application, and the descriptions of the embodiments above are only for the purpose of helping to understand this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An embedded magnetic core assembly, characterized in that, It includes a first dielectric layer, an adhesive layer, a second dielectric layer, and a toroidal magnetic core stacked in sequence; The first dielectric layer is provided with a first annular blind groove, the adhesive layer is provided with an annular through groove, and the second dielectric layer is provided with a second annular blind groove. The first annular blind groove, the annular through groove, and the second annular blind groove are interconnected. The annular magnetic core is disposed in the first annular blind slot, the annular through slot, and the second annular blind slot, and the adhesive layer is bonded to the periphery of the annular magnetic core to fix the annular magnetic core.

2. The embedded magnetic core assembly according to claim 1, characterized in that, The adhesive layer is located within the first annular blind groove and / or the second annular blind groove, and is bonded to the sidewall of the annular magnetic core.

3. The embedded magnetic core assembly according to claim 2, characterized in that, The adhesive layer is located on the bottom wall of the first annular blind groove and / or the bottom wall of the second annular blind groove, and is bonded to the bottom wall and the side wall of the annular magnetic core.

4. The embedded magnetic core assembly according to claim 1, characterized in that: The first medium layer is provided with a first venting groove, which is connected to the first annular blind groove; The adhesive layer is provided with a venting groove, which is connected to the annular groove. The second medium layer is provided with a second venting groove, which is connected to the second annular blind groove; The first exhaust duct and / or the second exhaust duct are connected to the outside.

5. The embedded magnetic core assembly according to claim 4, characterized in that: The bottom wall of the first exhaust channel is provided with a first exhaust hole, which connects the first exhaust channel to the outside; and / or The bottom wall of the second exhaust groove is provided with a second exhaust hole, which connects the second exhaust groove to the outside.

6. The embedded magnetic core assembly according to any one of claims 1 to 5, characterized in that, The height between the bottom wall of the first annular blind slot and the bottom wall of the second annular blind slot is H, and the thickness of the annular magnetic core is C, where H is greater than C.

7. The embedded magnetic core assembly according to claim 6, characterized in that, The distance between the medium layer and the bottom wall of the second annular blind groove is D, where 0.1H <D<0.9H。 8. The embedded magnetic core assembly according to any one of claims 1 to 5, characterized in that, The widths of the first annular blind slot, the annular through slot, and the second annular blind slot are greater than the width of the annular magnetic core.

9. A transformer, characterized in that, include: The embedded magnetic core assembly as described in any one of claims 1 to 8; A first metal layer is disposed on the side of the first dielectric layer away from the adhesive layer, and a plurality of first traces and a plurality of second traces spaced apart from each other are disposed on the first metal layer; A second metal layer is disposed on the side of the second dielectric layer away from the adhesive layer, and multiple third traces and multiple fourth traces are disposed on the second metal layer at intervals between them; The plurality of first traces and the plurality of third traces are connected in series and wound around the annular magnetic core to form a primary coil. The multiple second traces and the multiple fourth traces are connected in series and wound around the annular magnetic core to form a secondary coil.

10. A circuit board, characterized in that, Includes the transformer as described in claim 9.

Images