Circuit board with embedded magnetic core

Abstract

The utility model discloses a circuit board with embedded magnetic cores. The disclosed embedded magnetic core circuit board comprises a first circuit substrate, a second circuit substrate and a magnetic core layer arranged between the first circuit substrate and the second circuit substrate, wherein the thickness difference between the first circuit substrate and the second circuit substrate is less than 0.1 mm; the magnetic core layer comprises an embedded magnetic core plate, a magnetic core and adhesive films, the magnetic core is arranged in the embedded magnetic core plate, and the adhesive films are adhered to the surfaces of the two sides of the embedded magnetic core plate and the magnetic core and clamp the magnetic core; a planar coil is arranged in the first circuit substrate, and the planar coil is located in the outer contour range of the magnetic core in the thickness direction of the magnetic core embedded circuit board. The circuit board with the embedded magnetic core has the advantages of being high in structural stability and convenient to process.

Description

Technical Field

[0001] The utility model relates to the field of circuit boards; more specifically, to a circuit board with an embedded magnetic core and a coil structure. Background Art

[0002] Wireless charging systems primarily utilize the principle of electromagnetic induction, coupling energy through coils to achieve energy transfer. In some existing technologies, the inductor coil at the transmitter end of a wireless charging system is arranged as a planar coil on a circuit board, with a magnetic core embedded in the circuit board to enhance the electromagnetic induction effect.

[0003] In the prior art, the inductor coil and its control circuit are usually respectively arranged in different circuit substrates located on opposite sides of the magnetic core layer. The circuit substrates located on opposite sides of the magnetic core layer have different thicknesses, which may cause the circuit board to warp and deform easily. Utility Model Content

[0004] The main purpose of the utility model is to provide a buried magnetic core circuit board which has high structural stability and is easy to process.

[0005] In order to achieve the above-mentioned main purpose, the utility model provides a buried magnetic core circuit board, comprising a first circuit substrate, a second circuit substrate and a magnetic core layer arranged between the first circuit substrate and the second circuit substrate, the thickness difference between the first circuit substrate and the second circuit substrate is less than 0.1 mm; wherein, the magnetic core layer comprises a buried magnetic core plate, a magnetic core and an adhesive film, the magnetic core is arranged in the buried magnetic core plate, the adhesive film is bonded to the buried magnetic core plate and the two side surfaces of the magnetic core and clamps the magnetic core; a planar coil is provided inside the first circuit substrate; in the thickness direction of the buried magnetic core circuit board, the planar coil is located within the outer contour of the magnetic core.

[0006] According to a specific embodiment of the present invention, the first circuit substrate includes a shielding circuit layer arranged on its outer surface and an inductor coil layer arranged inside thereof, and the inductor coil layer is provided with the planar coil.

[0007] Furthermore, the inductor coil layer includes an L2 inductor coil layer and an L3 inductor coil layer, the L2 inductor coil layer is located between the shielding circuit layer and the L3 inductor coil layer, and both the L2 inductor coil layer and the L3 inductor coil layer are provided with the planar coil.

[0008] Furthermore, the planar coil includes a first planar coil arranged in the L2 inductor coil layer, a second planar coil and a third planar coil arranged in the L3 inductor coil layer; in the thickness direction of the buried magnetic core circuit board, the second planar coil and the third planar coil both partially overlap with the first planar coil.

[0009] Furthermore, the second planar coil and the third planar coil are symmetrically arranged relative to a horizontal imaginary center line, and the first planar coil has a symmetrical structure relative to the imaginary center line.

[0010] According to a specific embodiment of the present invention, the thickness of the planar coil is 100 μm to 180 μm.

[0011] According to a specific embodiment of the present invention, the second circuit substrate is provided with a plurality of control circuit layers.

[0012] Furthermore, the planar coil of the first circuit substrate is electrically connected to the control circuit layer of the second circuit substrate through a conductive via.

[0013] The technical solution of the utility model has the following beneficial effects:

[0014] In this utility model, the thickness difference between the first and second circuit substrates on opposite sides of the magnetic core layer is less than 0.1 mm, which helps reduce internal stress in the circuit board and prevents warping. The adhesive film adhered to both sides of the embedded core plate and the magnetic core to clamp the core, not only improving the core's positioning accuracy but also facilitating processing.

[0015] Furthermore, by optimizing the design of the inductor coil, it is beneficial to improve the electromagnetic induction effect and wireless charging efficiency.

[0016] In order to more clearly illustrate the purpose, technical solutions and advantages of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 2 is a schematic structural diagram of a magnetic core embedded circuit board in an embodiment;

[0018] Figure 2 2 is a schematic structural diagram of the magnetic core layer before lamination in the embodiment;

[0019] Figure 3 Schematic diagram of the layout structure of the magnetic core and the planar coil in the embodiment. DETAILED DESCRIPTION

[0020] The following description describes the technical solution of the present invention in detail in conjunction with specific embodiments. However, the present invention can also be implemented in other variable ways based on this description. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0021] like Figure 1As shown, the embedded magnetic core circuit board as an embodiment includes a first circuit substrate 11, a second circuit substrate 12, and a magnetic core layer 20 disposed between the first circuit substrate 11 and the second circuit substrate 12. The thickness difference between the first circuit substrate 11 and the second circuit substrate 12 is less than 0.1 mm, preferably less than 0.05 mm, to reduce internal stress in the circuit board and prevent warping of the circuit board.

[0022] like Figure 2 As shown, the magnetic core layer 20 includes an embedded magnetic core plate 21, a magnetic core 22, and an adhesive film 23. The magnetic core 22 is disposed within a receiving through-hole 211 of the embedded magnetic core plate 21. The adhesive film 23 is adhered to both sides of the embedded magnetic core plate 21 and the magnetic core 22 to hold the magnetic core 22. The thickness of the adhesive film 23 can be, but is not limited to, 25 μm to 35 μm.

[0023] The magnetic core layer 20 can be fixed between the first circuit substrate 11 and the second circuit substrate 12 by lamination. Specifically, semi-cured adhesive sheets 112b and 122b can be respectively arranged between the magnetic core layer 20 and the first circuit substrate 11 and the second circuit substrate 12 for lamination. During the lamination process, the adhesive film 23 breaks at the connection between the embedded magnetic core plate 21 and the magnetic core 22, forming a gap. A portion of the semi-cured adhesive sheets 112b and 122b flows to fill the space within the accommodating through hole 211 not occupied by the magnetic core 22 and solidifies, thereby fixing the magnetic core 22 within the embedded magnetic core plate 21. The adhesive film 23 can be in a semi-cured state before lamination and solidifies during the lamination process.

[0024] In the embodiment, due to the bonding effect of the adhesive film 23, the magnetic core 22 can be reliably positioned in the buried magnetic core plate 21 before the magnetic core layer 20 is pressed and fixed. Even if the magnetic core layer 20 is flipped over, the magnetic core 22 will not fall out of the accommodating through hole 211, which facilitates the removal and placement of the magnetic core layer 20 and the transfer between different workstations, thereby facilitating the processing of the circuit board.

[0025] The first circuit substrate 11 includes an L1 shielding circuit layer arranged on the outer surface and a planar coil C arranged inside the first circuit substrate 11 . The planar coil C is located within the outer contour of the magnetic core 22 in the thickness direction of the embedded magnetic core circuit board.

[0026] In this embodiment, the first circuit substrate 11 includes an L2 inductor layer and an L3 inductor layer. The L2 inductor layer is located between the L1 shielding circuit layer and the L3 inductor layer, meaning that the L3 inductor layer is closer to the magnetic core 22 than the L2 inductor layer. Both the L2 and L3 inductor layers are formed with a planar coil C. The thickness of the planar coil C can range from 100 μm to 180 μm, but is not limited thereto.

[0027] For example, Figure 3As shown, the planar coils C include a first planar coil C21 disposed in the L2 inductor layer, and a second planar coil C32 and a third planar coil C33 disposed in the L3 inductor layer. In the thickness direction of the embedded magnetic core circuit board, the second planar coil C32 and the third planar coil layer C33 partially overlap with the first planar coil C21. Preferably, the second planar coil C32 and the third planar coil C33 are symmetrically arranged relative to a horizontal imaginary centerline L, and the first planar coil C21 has a symmetrical structure relative to the imaginary centerline L.

[0028] In this embodiment, the L2 inductor layer and the L3 inductor layer are disposed on opposite sides of a first insulating core board 111 (e.g., an FR-4 core board) to form a first core board assembly. The first core board assembly can utilize a double-sided copper-clad insulating core board, with the copper foil layers on both sides of the insulating core board etched to form the inductor layers. The L1 shielding circuit layer is bonded to the outside of the first core board assembly via an adhesive sheet 112a.

[0029] The second circuit substrate 12 includes multiple control circuit layers. Exemplarily, the control circuit layers include circuit layers L4 through L7. The L5 and L6 circuit layers are disposed on opposite sides of a second insulating core board 121 (e.g., an FR-4 core board) to form a second core board assembly. Adhesive sheets 122a are disposed on the inner and outer sides of the second core board assembly to bond the L4 and L7 circuit layers.

[0030] Furthermore, the control circuit layer of the second circuit substrate 12 is electrically connected to the planar coil C of the first circuit substrate 11 through conductive vias 13, which can be filled with plugging resin 14. If necessary, the conductive vias 13 can also be electrically connected to the L1 shielding circuit layer.

[0031] Although the present invention has been disclosed above with reference to specific embodiments, these embodiments are not intended to limit the scope of the present invention. Any person skilled in the art may make modifications or variations without departing from the scope of the present invention. Any equivalent modifications made in accordance with the present invention shall be covered by the scope of protection of the present invention.

Claims

1. A buried magnetic core circuit board, characterized in that: The embedded magnetic core circuit board includes a first circuit substrate, a second circuit substrate, and a magnetic core layer disposed between the first circuit substrate and the second circuit substrate; wherein the difference in thickness between the first circuit substrate and the second circuit substrate is less than 0.1 mm; The magnetic core layer includes a buried magnetic core plate, a magnetic core and an adhesive film, wherein the magnetic core is arranged in the buried magnetic core plate, and the adhesive film is adhered to both sides of the buried magnetic core plate and the magnetic core to clamp the magnetic core; A planar coil is provided inside the first circuit substrate; in the thickness direction of the embedded magnetic core circuit board, the planar coil is located within the outer contour of the magnetic core.

2. The embedded magnetic core circuit board according to claim 1, wherein: The first circuit substrate includes a shielding circuit layer arranged on its outer surface and an inductor coil layer arranged inside thereof, and the inductor coil layer is provided with the planar coil.

3. The embedded magnetic core circuit board according to claim 2, wherein: The inductor coil layer includes an L2 inductor coil layer and an L3 inductor coil layer. The L2 inductor coil layer is located between the shielding circuit layer and the L3 inductor coil layer. Both the L2 inductor coil layer and the L3 inductor coil layer are provided with the planar coil.

4. The embedded magnetic core circuit board according to claim 3, wherein: The planar coil includes a first planar coil arranged in the L2 inductor coil layer, a second planar coil and a third planar coil arranged in the L3 inductor coil layer; in the thickness direction of the buried magnetic core circuit board, the second planar coil and the third planar coil both partially overlap with the first planar coil.

5. The embedded magnetic core circuit board according to claim 4, characterized in that: The second planar coil and the third planar coil are symmetrically arranged with respect to a horizontal imaginary center line, and the first planar coil has a symmetrical structure with respect to the imaginary center line.

6. The embedded magnetic core circuit board according to claim 1, wherein: The thickness of the planar coil is 100 μm to 180 μm.

7. The embedded magnetic core circuit board according to claim 1, wherein: The second circuit substrate is provided with a plurality of control circuit layers.

8. The embedded magnetic core circuit board according to claim 7, wherein: The planar coil of the first circuit substrate is electrically connected to the control circuit layer of the second circuit substrate through a conductive via.

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