Circuit board with embedded inductor and manufacturing method thereof

Abstract

The invention provides a circuit board with an embedded inductor. The circuit board comprises a circuit substrate, a magnetic material ring and two metal coil structures, the magnetic material ring is embedded in the circuit substrate, and the two metal coil structures are respectively wound on two opposite blocks of the magnetic material ring. The metal coil structures are electrically connected to the circuit substrate, and the metal coil structures are not electrically connected. The coil turns of the metal coil structures are the same, and the coil winding directions of the metal coil structures are opposite. The central axis of the magnetic material ring extends along the plane of the circuit substrate. Therefore, the process of arranging the common mode inductor on the circuit board is simplified, and the thinning of the circuit board is realized.

Description

Technical Field

[0001] The present invention relates to a circuit board, and more particularly to a circuit board with embedded electronic components. Background Art

[0002] A common mode choke is two sets of coils symmetrically wound in opposite directions but with the same number of turns on a closed magnetic ring. Since the common mode choke can act as a filter for electromagnetic interference of common mode signals and suppress the electromagnetic waves generated by electromagnetic signal lines from radiating outward, it can improve the electromagnetic compatibility (EMC) of the circuit board. Generally, after the common mode choke is manufactured, it is then disposed on the circuit board by welding, and the manufacturing process is relatively complicated, and the improvement of the module yield is also limited by the welding yield. In addition, under the development trend of the thinning of electronic components, the magnetic ring holes are also reduced accordingly, which in turn causes difficulties in winding the coils. Summary of the Invention

[0003] Therefore, the present invention provides a circuit board with an embedded common mode choke and a manufacturing method thereof to omit the process of welding the common mode choke to the circuit board.

[0004] The present invention provides a circuit board with an embedded inductor. The circuit board includes a circuit substrate, a magnetic material ring, and two metal coil structures. The magnetic material ring is embedded in the circuit substrate, and the two metal coil structures are respectively wound around opposite two blocks of the magnetic material ring. The metal coil structures are respectively electrically connected to the circuit substrate, and there is no electrical connection between the metal coil structures. The number of turns of the coils of each metal coil structure is the same, and the winding directions of the coils of the metal coil structures are opposite. The central axis of the magnetic material ring extends along the plane of the circuit substrate.

[0005] In at least one embodiment of the present invention, the material of the magnetic material ring includes a ferrite material.

[0006] In at least one embodiment of the present invention, the circuit substrate includes a first insulating layer and two first circuit layers. The first insulating layer is located between the first circuit layers. One end of each metal coil structure is connected to one of the first circuit layers, and the other end of each metal coil structure is connected to the other first circuit layer.

[0007] In at least one embodiment of the present invention, the circuit board further includes two second insulating layers and two second circuit layers. The two second insulating layers are located between the first circuit layers, and the first insulating layer is located between the second insulating layers. The two second circuit layers are located between the second insulating layers, and the first insulating layer is located between the second circuit layers. The block of the magnetic material ring extends from one surface of the circuit board through the first insulating layer, the second insulating layer, and the second circuit layer to the other surface of the circuit board.

[0008] In at least one embodiment of the present invention, opposite end faces of the magnetic material ring are respectively exposed to the circuit board and flush with the surface of the circuit board.

[0009] The present invention also provides a method for manufacturing a circuit board with an embedded inductor. This method includes providing a substrate including two first metal layers, and the first metal layers are respectively located on opposite sides of the substrate; removing a part of the substrate to respectively form grooves on opposite surfaces of the substrate; after forming the grooves, removing another part of the substrate to form two threaded through holes in the substrate, where each threaded through hole communicates with the grooves on both sides; depositing a metal material on the inner walls of the threaded through holes and the grooves; removing a part of the metal material to respectively form metal coil structures on the inner walls of the threaded through holes, where one end of each metal coil structure is connected to one of the first metal layers, and the other end is connected to the other first metal layer, there is no electrical connection between the metal coil structures, and the number of turns of the coils of each metal coil structure is the same, and the winding directions of the coils of each metal coil structure are opposite; after forming the metal coil structures, disposing a magnetic material in the threaded through holes and the grooves; and after disposing the magnetic material, patterning the first metal layer to form two first circuit layers.

[0010] In at least one embodiment of the present invention, the method for forming the substrate includes providing a first composite substrate, which includes a first insulating layer and two second metal layers disposed on the first insulating layer, where the first insulating layer is located between the second metal layers; patterning the second metal layers to form two second circuit layers; on the second circuit layers, respectively laminating second composite substrates so that the second circuit layers are located between the second composite substrates. The second composite substrates respectively include one of the first metal layers and a second insulating layer. The second insulating layer is located between one of the first metal layers and one of the second circuit layers.

[0011] In at least one embodiment of the present invention, removing a part of the substrate includes removing a part of each first metal layer; and after removing a part of each first metal layer, removing a part of each second insulating layer.

[0012] In at least one embodiment of the present invention, the magnetic material includes a ferrite material.

[0013] In at least one embodiment of the present invention, the method of depositing a metal material on the inner walls of the threaded through-holes and the grooves includes horizontal continuous plating (HCP) and vertical continuous plating (VCP).

[0014] Based on the above, at least one embodiment of the present invention uses an embedded method to bury a common-mode inductor in a circuit board to achieve the thinning of the circuit board module. In addition, since the soldering process of setting the common-mode inductor on the circuit board is omitted, the failure caused by poor soldering is avoided. Therefore, it helps to improve the yield rate of the circuit board module. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] As can be understood from the following detailed description and in conjunction with the drawings. It should be noted that various features are not drawn to the scale of industrial practice standards. In fact, for the sake of clarity and understanding in discussion, the dimensions of various features can be arbitrarily increased or decreased.

[0016] Figure 1 A cross-sectional view of a circuit board with an embedded inductor showing at least one embodiment of the present invention.

[0017] Figures 2A to 2F A cross-sectional view of a method for manufacturing a circuit board with an embedded inductor showing at least one embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The present invention will be described in detail with the following embodiments. It should be noted that the following description of the embodiments of the present invention is only for illustrative purposes here and is not intended to disclose all implementation aspects in detail or limit the specific implementation aspects of the present invention. For example, the description of "the first feature is formed on the second feature" includes various implementation manners, which cover the direct contact between the first feature and the second feature, and also cover the formation of additional features between the first feature and the second feature so that the two do not directly contact. In addition, the same reference numerals used in the drawings and the specification will denote the same or similar elements as much as possible.

[0019] Spatially relative terms, such as "lower layer", "below", "beneath", "above", "upper", etc., are used herein to simply describe the relationship of an element or feature shown in the figure to another element or feature. These spatially relative terms cover different orientations in addition to the orientations depicted in the figures when the device is in use or operation. In addition, when an element is rotatable (rotating 90 degrees or other angles), the spatially relative descriptive terms used herein can also be interpreted correspondingly.

[0020] Moreover, when describing a number or a range of numbers with terms such as "about", "approximately", etc., such terms are intended to cover numbers within a reasonable range, taking into account the natural variations that would be understood by a person of ordinary skill in the art during the manufacturing process. A numerical range covers a reasonable range including the numbers described. For example, within + / - 10% of the numbers described, based on known manufacturing tolerances, which are related to the characteristics of the manufacturing feature. For example, a material layer with a thickness of "about 5 nanometers" can cover a size range from 4.25 nanometers to 5.75 nanometers, where the manufacturing tolerance of + / - 15% for depositing the material layer is known to a person of ordinary skill in the art. Further, the present invention may repeat reference numerals and / or labels in various examples. This repetition is for the purpose of simplification and clarity, and is not intended to indicate a relationship between the various embodiments and / or configurations discussed therein.

[0021] The present invention provides a circuit board 100 with embedded inductors. Please refer to Figure 1 , the circuit board 100 with embedded inductors includes a circuit board substrate 120, a magnetic material ring 140, and two metal coil structures 160a and 160b. The circuit board substrate 120 includes an insulating layer 122 and two circuit layers 123a and 123b, where the insulating layer 122 is located between the circuit layers 123a and 123b. In addition, the circuit board substrate 120 further includes two insulating layers 124a and 124b and two circuit layers 125a and 125b. The insulating layers 124a and 124b are located between the circuit layers 123a and 123b, and the insulating layer 122 is located between the insulating layers 124a and 124b. The circuit layers 125a and 125b are located between the insulating layers 124a and 124b, and the insulating layer 122 is located between the circuit layers 125a and 125b.

[0022] In addition, although not shown in the figures, the circuit board 100 with embedded inductors may further include a plurality of conductive buried vias or conductive blind vias. The above-mentioned conductive buried vias or conductive blind vias are disposed between the respective circuit layers (including the circuit layers 123a and 123b, the circuit layers 125a and 125b) to electrically connect the respective circuit layers.

[0023] As Figure 1As shown, the magnetic material ring 140 is embedded in the circuit board 120. The magnetic material ring 140 has the property of spontaneous magnetization, and the magnetic material ring 140 is made of ferromagnetic material or ferrimagnetic material. In this embodiment, the magnetic material ring 140 may include ferrite material, such as a low coercivity soft magnetic material or the like including iron oxide and nickel zinc (NiZn) or manganese zinc (MnZn), wherein the aforementioned iron oxide is a ceramic material, so the magnetic material ring 140 can be an insulator. In this embodiment, the opposite end faces 140e of the magnetic material ring 140 are respectively exposed on the surface 120s of the circuit board 120 and flush with the surface 120s of the circuit board 120, but the present invention is not limited thereto.

[0024] For example, in at least one embodiment, the circuit board 120 can completely cover the opposite end faces 140e of the magnetic material ring 140. Or, in another embodiment, the circuit board 120 exposes the opposite end faces 140e of the magnetic material ring 140, but the end faces 140e can be concave or convex with respect to the surface 120s of the circuit board 120.

[0025] It should be particularly mentioned that the magnetic material ring 140 can be a ring of various shapes, such as a circular ring or a rectangular ring. Specifically, in this embodiment, the magnetic material ring 140 is a rectangular ring, and two of the blocks 140r of the magnetic material ring 140 respectively correspond to the opposite two sides of the rectangular ring, that is, these two blocks 140r of the magnetic material ring 140 are not directly connected to each other. The blocks 140r of the magnetic material ring 140 extend from the surface 120s of the circuit board 120 through the insulating layer 122, insulating layers 124a and 124b, and circuit layers 125a and 125b to the other surface 120s of the circuit board 120. In addition, as Figure 1 shown, the central axis of the magnetic material ring 140 (i.e., the axis extending through the center point A1) extends along the plane 120p of the circuit board 120. In other words, the magnetic material ring 140 is vertically embedded in the circuit board 120.

[0026] The metal coil structures 160a and 160b are respectively wound around the opposite two blocks 140r of the magnetic material ring 140. Specifically, the metal coil structure 160a is wound around Figure 1 the left block 140r, while the metal coil structure 160b is wound around Figure 1The right block 140r. The metal coil structures 160a and 160b are electrically connected to the circuit board 120 respectively, where the metal coil structure 160a is connected to the circuit layers 123a and 123b of the circuit board 120, and the metal coil structure 160b is also connected to the circuit layers 123a and 123b of the circuit board 120.

[0027] Specifically, one end of the metal coil structure 160a is connected to the circuit layer 123a, and the other end of the metal coil structure 160a is connected to the circuit layer 123b; one end of the metal coil structure 160b is connected to the circuit layer 123a, and the other end of the metal coil structure 160b is connected to the circuit layer 123b. The materials of the metal coil structures 160a and 160b may include copper.

[0028] It should be particularly mentioned that there is no electrical connection between the metal coil structure 160a and the metal coil structure 160b. The so-called "no electrical connection" here means that the metal coil structures 160a and 160b will not be directly electrically conductive. Specifically, since the magnetic material ring 140 made of ferrite material is an insulator, the metal coil structures 160a and 160b cannot be electrically conductive to each other through the magnetic material ring 140. Secondly, the metal coil structures 160a and 160b do not contact each other, so the metal coil structures 160a and 160b will not be directly electrically conductive. However, it must be noted that since the metal coil structures 160a and 160b are both wound around the same magnetic material ring 140, even though the metal coil structures 160a and 160b are not directly electrically conductive, the magnetic material ring 140 can use the method of electromagnetic induction to transfer current between the metal coil structures 160a and 160b.

[0029] It is worth mentioning that the number of turns of the metal coil structure 160a is the same as that of the metal coil structure 160b, and the winding direction of the metal coil structure 160a is opposite to that of the metal coil structure 160b. For example, when observing from the perspective of the direction D1, the metal coil structure 160a is wound around the magnetic material ring 140 in the counterclockwise direction, while the metal coil structure 160b is wound around the magnetic material ring 140 in the clockwise direction.

[0030] Since the number of turns of the metal coil structure 160a in the circuit board 100 with embedded inductors is the same as that of the metal coil structure 160b, and the winding directions of the coils of the metal coil structures 160a and 160b are opposite. Therefore, when the circuit board 120 is powered on and the currents flowing through the metal coil structures 160a and 160b travel in the same direction (for example, from the circuit layer 123a towards the circuit layer 123b), the magnetic material ring 140 disposed in the circuit board 120 and the two metal coil structures 160a and 160b can form a common-mode inductor embedded in the circuit board 120 to provide the effect of electromagnetic shielding when the circuit board 100 with embedded inductors operates, thereby filtering common-mode electromagnetic interference.

[0031] The present invention provides a manufacturing method for a circuit board with embedded inductors. Taking the circuit board 100 with embedded inductors as an example, this manufacturing method may include several steps as Figures 2A to 2F shown. First, please refer to Figure 2A , provide a substrate 220. The substrate 220 includes two metal layers 223a and 223b, and the metal layers 223a and 223b are respectively located on opposite sides of the substrate 220. The forming step of the substrate 220 includes: providing a first composite substrate (not labeled), which includes an insulating layer 122 and two metal layers (not labeled) disposed on the insulating layer 122, and the insulating layer 122 is located between these two metal layers. Then, the above two metal layers can be patterned by etching to form two circuit layers 125a and 125b.

[0032] Next, the second composite substrates 230a and 230b can be respectively laminated on the circuit layers 125a and 125b by thermocompression lamination, so that the circuit layers 125a and 125b are located between the second composite substrates 230a and 230b. The second composite substrate 230a includes a metal layer 223a and an insulating layer 124a, and the second composite substrate 230b includes a metal layer 223b and an insulating layer 124b. The insulating layer 124a is located between the metal layer 223a and the circuit layer 125a, and the insulating layer 124b is located between the metal layer 223b and the circuit layer 125b. So far, the substrate 220 as shown in Figure 2A has been roughly formed.

[0033] After providing the substrate 220, please refer to Figure 2B, a part of the substrate 220 can be removed by, for example, plasma surface etching to form grooves 228a and 228b on two opposite surfaces 220s of the substrate 220 respectively. In particular, this step further includes removing a part of the metal layers 223a and 223b. After removing a part of the metal layers 223a and 223b, a part of the insulating layers 124a and 124b is removed. Although in this embodiment, this step only removes a part of the metal layers 223a and 223b and a part of the insulating layers 124a and 124b, the present invention is not limited thereto. For example, in the case where the grooves 228a and 228b are not connected, this step may further include removing a part of the insulating layer 122. In other words, in other embodiments, the depths of the grooves 228a and 228b can be deeper.

[0034] Next, please refer to Figure 2C , after forming the grooves 228a and 228b, another part of the substrate 220 can be removed by, for example, mechanical drilling to form two threaded through holes 229a and 229b in the substrate 220. The threaded through hole 229a communicates with the grooves 228a and 228b on both sides, and the threaded through hole 229b also communicates with the grooves 228a and 228b on both sides. In other words, the threaded through holes 229a and 229b penetrate the substrate 220 respectively.

[0035] Next, please refer to Figure 2D , a metal material 250 is deposited on the inner walls of the threaded through holes 229a and 229b and the grooves 228a and 228b. In this embodiment, the metal material 250 may include copper. It is worth mentioning that the method of depositing the metal material 250 on the inner walls of the threaded through holes 229a and 229b and the grooves 228a and 228b may include Horizental Continuous Plating (HCP) and Vertical Continuous Plating (VCP). Specifically, an initial metal material (not labeled) can be deposited on the inner walls of the threaded through holes 229a and 229b and the grooves 228a and 228b by Horizental Continuous Plating first, and the excess initial metal material is removed by laser cutting. Then, the initial metal material is thickened by Vertical Continuous Plating to form the metal material 250.

[0036] Please refer to Figure 2E, a part of the metal material 250 is removed by means of, for example, mechanical drilling to form metal coil structures 160a and 160b on the inner walls of the threaded through holes 229a and 229b respectively. One end of the metal coil structure 160a is connected to the metal layer 223a, and the other end of the metal coil structure 160a is connected to the metal layer 223b; one end of the metal coil structure 160b is connected to the metal layer 223a, and the other end of the metal coil structure 160b is connected to the metal layer 223b.

[0037] Next, please refer to Figure 2F , after the metal coil structures 160a and 160b are formed, magnetic materials 140' can be disposed in the threaded through holes 229a and 229b (marked in Figure 2E ) and the grooves 228a and 228b (marked in Figure 2D ) by means of, for example, plugging or printing. The magnetic materials 140' can include ferrite materials, such as low coercivity soft magnetic materials containing iron oxide and nickel zinc or manganese zinc or the like. In this embodiment, the magnetic materials 140' are substantially equivalent to the magnetic material rings 140.

[0038] After the magnetic materials 140' are disposed, the metal layers 223a and 223b can be patterned by means of, for example, etching to form the circuit layers 123a and 123b as shown in Figure 1 . So far, the circuit board 100 with embedded inductors as shown in Figure 1 has been substantially completed.

[0039] In summary, at least one embodiment of the present invention uses an embedded method to bury the common mode inductor in the circuit board. Compared with mounting the common mode inductor on the surface of the circuit board, it is more conducive to achieving the thinning of the circuit board module. On the other hand, since the formation process of the common mode inductor is incorporated into the circuit process of the circuit board and there is no need to set the common mode inductor on the circuit board through an additional soldering process, the failure situation in the soldering process is avoided, thereby improving the yield of the circuit board module.

[0040] Although the embodiments of the present invention have been disclosed above, they are not intended to limit the embodiments of the present invention. Any person skilled in the art can make some changes and modifications without departing from the spirit and scope of the embodiments of the present invention. Therefore, the protection scope of the embodiments of the present invention shall be determined by the scope defined by the appended claims.

[0041]

Symbolic Explanation

[0042] 100: Circuit board with embedded inductor

[0043] 120: Circuit substrate

[0044] 120s, 220s: Surface

[0045] 120p: Plane

[0046] 122, 124a, 124b: Insulating layer

[0047] 123a, 123b, 125a, 125b: Circuit layer

[0048] 140: Magnetic material ring

[0049] 140’: Magnetic material

[0050] 140e: End face

[0051] 140r: Block

[0052] 160a, 160b: Metal coil structure

[0053] 220: Substrate

[0054] 223a, 223b: Metal layer

[0055] 228a, 228b: Groove

[0056] 229a, 229b: Threaded through-hole

[0057] 230a, 230b: Second composite substrate

[0058] 250: Metal material

[0059] A1: Center point

[0060] D1: Direction.

Claims

1. A circuit board with embedded inductors, characterized in that, Comprising: A circuit board; A magnetic material ring embedded in the circuit board; and Two metal coil structures respectively wound around opposite two blocks of the magnetic material ring, wherein the metal coil structures are respectively electrically connected to the circuit board, and there is no electrical connection between the metal coil structures; Wherein the number of turns of the coils of each of the metal coil structures is the same, and the winding directions of the coils of the metal coil structures are opposite; Wherein the central axis of the magnetic material ring extends along the plane of the circuit board.

2. The circuit board with embedded inductors according to claim 1, characterized in that, The material of the magnetic material ring comprises a ferrite material.

3. The circuit board with embedded inductors according to claim 1, characterized in that, The circuit board comprises: A first insulating layer; and Two first circuit layers, wherein the first insulating layer is located between the first circuit layers, and one end of each of the metal coil structures is connected to one of the first circuit layers, and the other end of each of the metal coil structures is connected to the other of the first circuit layers.

4. The circuit board with embedded inductors according to claim 3, characterized in that, The circuit board further comprises: Two second insulating layers located between the first circuit layers, wherein the first insulating layer is located between the second insulating layers; and Two second circuit layers located between the second insulating layers, and the first insulating layer is located between the second circuit layers, wherein the blocks of the magnetic material ring extend from the surface of the circuit board through the first insulating layer, the second insulating layer and the second circuit layer to the other surface of the circuit board.

5. The circuit board with embedded inductors according to claim 4, characterized in that, The opposite two end faces of the magnetic material ring are respectively exposed to the circuit board and are flush with the surface of the circuit board.

6. A manufacturing method of a circuit board with embedded inductors, characterized in that, Comprising: Providing a substrate, the substrate comprising: Two first metal layers respectively located on opposite two sides of the substrate; Removing a part of the substrate to respectively form grooves on opposite two surfaces of the substrate; After forming the grooves, removing another part of the substrate to form two threaded through holes in the substrate, wherein each of the threaded through holes communicates with the grooves on both sides; Depositing a metal material on the inner walls of the threaded through holes and the grooves; Removing a part of the metal material to respectively form metal coil structures on the inner walls of the threaded through holes, wherein one end of each of the metal coil structures is connected to one of the first metal layers, and the other end of each of the metal coil structures is connected to the other of the first metal layers, and there is no electrical connection between the metal coil structures, wherein the number of turns of the coils of each of the metal coil structures is the same, and the winding directions of the coils of the metal coil structures are opposite; After forming the metal coil structures, disposing a magnetic material in the threaded through holes and the grooves; and After disposing the magnetic material, patterning the first metal layer to form two first circuit layers.

7. The method according to claim 6, characterized in that, The forming method of the substrate comprises: Providing a first composite substrate, wherein the first composite substrate comprises: A first insulating layer; and Two second metal layers disposed on the first insulating layer, wherein the first insulating layer is located between the second metal layers; Patterning the second metal layer to form two second circuit layers; On the second circuit layer, second composite substrates are respectively bonded so that the second circuit layer is located between the second composite substrates, wherein the second composite substrates respectively include: One of the first metal layers; And A second insulating layer, located between one of the first metal layers and one of the second circuit layers.

8. The method according to claim 7, wherein Removing a part of the substrate includes: Removing a part of each of the first metal layers; and After removing a part of each of the first metal layers, removing a part of each of the second insulating layers.

9. The method according to claim 6, wherein The magnetic material includes a ferrite material.

10. The method according to claim 6, wherein The method of depositing the metal material on the inner walls of the threaded through holes and the grooves includes horizontal continuous electroplating and vertical continuous electroplating.

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