Side wall coupling groove of circuit board and preparation method thereof and circuit board

Abstract

This invention relates to a sidewall coupling groove of a circuit board, its fabrication method, and the circuit board itself, belonging to the field of high-frequency microwave radio frequency. The circuit board includes a first shielding layer, a second shielding layer, and an inner dielectric layer disposed between the first and second shielding layers. A first circuit and a second circuit are arranged in the inner dielectric layer. A through-slot of a first predetermined length is formed on the circuit board. A first metal layer is electroplated on the first sidewall of the through-slot, and a second metal layer is electroplated on the second sidewall of the through-slot. The first metal layer connects to the first circuit, and the second metal layer connects to the second circuit. This invention, by forming a through-slot on the circuit board and performing sidewall metallization after milling, enables wireless power transmission between different traces on the circuit board through the sidewall coupling groove, reducing coupling loss caused by trace alignment deviations in the prior art. The intermediate coupling medium is air or pure resin, which can further reduce coupling loss.

Description

Technical Field

[0001] The present invention relates to the field of high-frequency microwave radio frequency, and in particular to a sidewall coupling groove of a circuit board, a preparation method thereof, and a circuit board. Background Art

[0002] The circuit board in the prior art is usually provided with an interlayer coupling structure, which uses the positions of the same-level routing or different-level routing in the vertical direction in the circuit board to adjust and realize wireless signal connection and energy transmission between different routings.

[0003] As shown in FIG. 1( a ) and FIG. 1( b ), the interlayer vertical coupling structure of the circuit board has a first vertical line 13 and a second vertical line 14 arranged in the coupling medium layer 12 between the two routing reference layers 11. The disadvantage of this interlayer vertical coupling structure is that the coupling between different layers is performed in a vertical alignment manner, which is also affected by the alignment degree and the change of the transmission medium, resulting in the coupling energy failing to reach the expected value.

[0004] As shown in FIG. 2( a ) and FIG. 2( b ), the interlayer horizontal coupling structure of the circuit board has the first line 23 and the second line 24 of the same horizontal layer arranged on the routing reference layer 21 and the coupling medium layer 22. The disadvantage of this interlayer horizontal coupling structure is that the wireless transmission energy of the routings of the same layer is unstable and is easily affected by the mutual influence of the transmission medium and the surrounding routings, resulting in a large loss of coupling energy.

[0005] In addition, the coupling medium layers of the above-mentioned interlayer horizontal coupling structure and interlayer vertical coupling structure both include glass cloth and resin, which will further increase the loss of coupling energy.

[0006] Therefore, how to reduce the coupling energy loss of the interlayer coupling structure of the circuit board has become an urgent problem to be solved. Summary of the invention

[0007] In view of the above technical problems, the present invention provides a sidewall coupling groove of a circuit board and a preparation method thereof and a circuit board, so as to solve the problem of large coupling energy loss in the interlayer coupling structure of the circuit board.

[0008] In a first aspect, the present invention provides a method for preparing a circuit board sidewall coupling groove, comprising:

[0009] A circuit board is provided, the circuit board comprising a first shielding layer, a second shielding layer, and an inner layer medium arranged between the first shielding layer and the second shielding layer, wherein a first circuit and a second circuit are arranged in the inner layer medium;

[0010] A through slot of a first preset length is provided on the circuit board;

[0011] Electroplating a metal layer on the sidewall of the through groove;

[0012] The metal layers at the two ends of the through slot are removed, and the first metal layer on the first side wall and the second metal layer on the second side wall of the through slot are retained, so that the first metal layer is connected to the first circuit and the second metal layer is connected to the second circuit, thereby forming a side wall coupling slot of the circuit board.

[0013] Optionally, the “opening a through slot of a first preset length on the circuit board” includes:

[0014] During the process of forming the through groove, the distance between two side walls of the through groove is controlled to be a first set distance.

[0015] Optionally, the “opening a through slot of a first preset length on the circuit board” further includes:

[0016] The through groove is obtained by performing laser milling or mechanical milling of the first preset length on the top layer of the circuit board of the preset thickness.

[0017] Optionally, the “removing the metal layers at two ends of the through groove” includes:

[0018] A secondary milling groove is performed at one end of the through slot with a second preset length, and a secondary milling groove is performed at the other end of the through slot with a third preset length, and the second preset length and the third preset length are equal or different, so as to remove the metal layer at the two ends.

[0019] Optionally, after the secondary groove milling, the preparation method further comprises:

[0020] Part of the surface metal of the first shielding layer and the second shielding layer is removed by etching, so that the remaining surface metal of the first shielding layer and the second shielding layer is not in contact with the metal layer on the side wall of the through groove.

[0021] Optionally, the preparation method further comprises:

[0022] The coupling groove on the side wall of the circuit board is filled with a coupling medium, wherein the coupling medium is pure resin or air.

[0023] In a second aspect, the present invention further provides a side wall coupling groove of a circuit board, comprising

[0024] The circuit board comprises a first shielding layer, a second shielding layer, and an inner layer medium arranged between the first shielding layer and the second shielding layer, wherein a first circuit and a second circuit are arranged in the inner layer medium;

[0025] A through slot of a first preset length is opened on the circuit board; a first metal layer is electroplated on the first side wall of the through slot, and a second metal layer is electroplated on the second side wall of the through slot, the first metal layer is connected to the first circuit, and the second metal layer is connected to the second circuit.

[0026] Optionally, the distance between the first side wall and the second side wall of the through slot is a first set distance.

[0027] Optionally, the coupling medium filled in the side wall coupling groove is pure resin or air.

[0028] Optionally, the first metal layer and the second metal layer are formed by performing secondary milling on two ends of the through slot to remove the metal layers at the two ends.

[0029] Optionally, the coupling area formula for forming the sidewall coupling groove is:

[0030] S=H*(L-a1-a2)

[0031] Among them, S is the coupling area of ​​the side wall coupling groove, H is the preset thickness of the circuit board, L is the first preset length, a1 is the second preset length of the secondary milling groove at one end of the through groove, and a2 is the third preset length of the secondary milling groove at the other end of the through groove.

[0032] Optionally, the first shielding layer and the second shielding layer do not contact the first metal layer and the second metal layer.

[0033] In a third aspect, the present invention further provides a circuit board, comprising:

[0034] The circuit board is provided with a side wall coupling groove prepared by the preparation method described in the first aspect.

[0035] The above scheme has the following beneficial effects:

[0036] The side wall coupling groove of the circuit board of the present invention, its preparation method and the circuit board are formed by opening a through groove of a first preset length on the circuit board; electroplating a metal layer on the side wall of the through groove; removing the metal layers at the two ends of the through groove, retaining the first metal layer on the first side wall of the through groove and the second metal layer on the second side wall, so that the first metal layer is connected to the first inner layer circuit of the circuit board, and the second metal layer is connected to the second inner layer circuit of the circuit board, so as to form the side wall coupling groove of the circuit board. The present invention realizes wireless energy transmission between different routings in the circuit board through the side wall coupling groove by opening a through groove on the circuit board and metallizing the side wall after the groove is milled, thereby reducing the coupling loss caused by the alignment deviation of the routing position in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG. 1( a ) is a top view of a horizontal coupling structure between layers of a circuit board provided in the prior art;

[0038] FIG1( b ) is a cross-sectional view of a horizontal coupling structure between layers of a circuit board provided in the prior art;

[0039] FIG. 2( a ) is a top view of an interlayer vertical coupling structure of a circuit board provided in the prior art;

[0040] FIG2( b ) is a cross-sectional view of an interlayer vertical coupling structure of a circuit board provided in the prior art;

[0041] Figure 3 is a diagram of a method for preparing a circuit board side wall coupling groove provided in an embodiment of the present invention;

[0042] Figure 3 (a) is a schematic diagram of a through slot of a first preset length provided on a circuit board in one embodiment of the present invention;

[0043] Figure 3 (b) is a schematic diagram of electroplating a metal layer on the side wall of a through groove provided in one embodiment of the present invention;

[0044] Figure 3 (c) is a schematic diagram of performing secondary milling on two ends of the through slot to remove the metal layer at the two ends provided in one embodiment of the present invention;

[0045] Figure 3 (d) is a schematic diagram of a first metal layer connected to a first circuit and a second metal layer connected to a second circuit in a thickness direction of a sidewall coupling groove provided in an embodiment of the present invention;

[0046] Figure 4 is a diagram of a method for preparing a circuit board side wall coupling groove provided in another embodiment of the present invention;

[0047] Figure 4 (a) is a top view of a circuit board with a portion of surface metal removed to form a groove, provided in one embodiment of the present invention;

[0048] Figure 4 (b) is a cross-sectional view of a circuit board provided in an embodiment of the present invention where a portion of the surface metal is removed to form a groove;

[0049] The symbols are explained as follows:

[0050] 31. shielding layer; 32. through slot; 33. metal layer; 331. first metal layer; 332. second metal layer;

[0051] 34. Groove; 35. Inner layer medium; 36. First circuit; 37. Second circuit. DETAILED DESCRIPTION

[0052] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0053] It should be understood that the embodiments set forth below represent the necessary information to enable those skilled in the art to implement the embodiments and illustrate the best mode for implementing the embodiments. After reading the following description in light of the accompanying drawings, those skilled in the art will understand the concepts of the present disclosure and will recognize applications of these concepts not specifically mentioned herein. It should be understood that these concepts and applications fall within the scope of the present disclosure and the appended claims.

[0054] It should also be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, the first element may be referred to as the second element, and similarly, the second element may be referred to as the first element without departing from the scope of the present disclosure. As used herein, the term "and / or" includes any and all combinations of one or more related listed items.

[0055] It should also be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or intervening elements may be present. Conversely, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements.

[0056] It should also be understood that the terms "upper", "lower", "left", "right", "front", "back", "bottom", "middle", "middle", "top", etc. may be used herein to describe various elements, and the indicated orientation or position relationship is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore these elements should not be limited by these terms.

[0057] These terms are only used to distinguish one element from another element. For example, a first element can be referred to as an "upper" element, and similarly, a second element can be referred to as an "upper" element according to the relative orientation of these elements without departing from the scope of the present disclosure.

[0058] It is further understood that the terms “comprises,” “includes,” “including” and / or “comprising” when used herein specify the presence of stated features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0059] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure belongs. It will be further understood that the terms used herein should be interpreted as having a meaning consistent with their meaning in the context of this specification and the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined as such herein.

[0060] In one embodiment, a method is provided as follows Figure 3 The method for preparing the circuit board side wall coupling groove shown includes the following steps:

[0061] S300, providing a circuit board, wherein the circuit board comprises a first shielding layer, a second shielding layer, and an inner layer medium disposed between the first shielding layer and the second shielding layer, wherein a first circuit and a second circuit are arranged in the inner layer medium.

[0062] The first shielding layer and the second shielding layer are used as routing reference layers. In addition, the circuit board provided in this step is a circuit board obtained after PCB pressing process, and before the PCB pressing process, the following steps are also included:

[0063] An inner layer dielectric is laid on the second shielding layer of the bottom layer, a first circuit (obtained by pattern transfer and pattern etching) is arranged on the inner layer dielectric, an inner layer dielectric is laid again on the first circuit, a second circuit (also obtained by pattern transfer and pattern etching) is arranged on the inner layer dielectric, an inner layer dielectric is laid again on the second circuit, and a first shielding layer is arranged on the inner layer dielectric.

[0064] S301, opening a through slot of a first preset length on a circuit board.

[0065] Among them, on the top layer of the circuit board (i.e., the shielding layer 31) with a preset thickness of H, a milling groove with a first preset length of L is performed to obtain a through groove 32, such as Figure 3 As shown in (a), the groove milling method can be laser groove milling or mechanical groove milling.

[0066] Optionally, in the process of forming the through groove 32, the distance between the two side walls of the through groove is controlled to be a first set distance W (W>0.1mm). Specifically, the size of the milling cutter can be used to control the first set distance W between the two side walls, which plays a role in controlling the coupling energy size of the wireless energy transmission between the wiring on the two side walls according to the set distance W. Taking interlayer coupling as an example, one indicator for evaluating wireless energy transmission is the coupling coefficient K, and its estimation formula is as follows:

[0067] K=(εr*S) / (4π*W*C0)

[0068] Wherein, εr is the relative dielectric constant of the coupling medium, S is the coupling area, W is the distance between the two side walls of the through slot, that is, the first set distance, and C0 is the equivalent capacitance of the circuit board.

[0069] S302, electroplating a metal layer on the sidewall of the through groove.

[0070] The sidewall metallization of the through slot 32 is achieved by chemical copper deposition and electroplating to obtain a metal layer 33 on the through slot 32, such as Figure 3 (b) as shown.

[0071] S303, remove the metal layers at the two ends of the through groove, retain the first metal layer on the first side wall and the second metal layer on the second side wall of the through groove, so that the first metal layer is connected to the inner first circuit of the circuit board, and the second metal layer is connected to the inner second circuit of the circuit board, to form a side wall coupling groove of the circuit board.

[0072] Wherein, secondary milling is performed at the two ends of the through slot 32 to remove the metal layer at the two ends, such as Figure 3 (c) As shown. Optionally, a second milling groove is performed at one end of the through slot 32 with a second preset length a1, and a second milling groove is performed at the other end of the through slot 32 with a third preset length a2, and the second preset length a1 and the third preset length a2 can be equal or different, and the first preset length and the second preset length are required to be greater than or equal to 0.1 mm. For example, Figure 3 In (c), the second preset length a1 is equal to the third preset length a2.

[0073] After the second preset length a1 and the third preset length a2 are used to mill the grooves at the two ends, the remaining length of the groove side wall metal is (L-a1-a2), that is, the lengths of the first metal layer 331 and the second metal layer 332 obtained after the second milling are both (L-a1-a2). Therefore, the coupling area formula for forming the side wall coupling groove is:

[0074] S=H*(L-a1-a2)

[0075] Wherein, S is the coupling area of ​​the side wall coupling groove, H is the preset thickness of the circuit board, L is the first preset length, a1 is the second preset length, and a2 is the third preset length.

[0076] After the secondary milling, a side wall coupling groove of the circuit board is formed, so that the first metal layer 331 in the side wall coupling groove is connected to the first line 36, and the second metal layer 332 in the side wall coupling groove is connected to the second line 37. Figure 3 (d) as shown.

[0077] The method for preparing the circuit board side wall coupling groove of this embodiment has the following advantages:

[0078] (1) By opening a through groove on the circuit board and metallizing the side wall after milling the groove, wireless energy transmission between different traces in the circuit board can be achieved through the side wall coupling groove, reducing the coupling loss caused by the alignment deviation of the trace position in the prior art by about 10-30%.

[0079] (2) The intermediate coupling medium between the first metal layer 331 and the second metal layer 332 of the sidewall coupling groove is air, and no other filler is needed, which can effectively reduce the coupling loss caused by using glass cloth as the coupling medium in the prior art.

[0080] In one embodiment, a method is provided as follows Figure 4 The method for preparing the circuit board side wall coupling groove shown includes the following steps:

[0081] S400, providing a circuit board, wherein the circuit board comprises a first shielding layer, a second shielding layer, and an inner layer medium disposed between the first shielding layer and the second shielding layer, wherein a first circuit and a second circuit are arranged in the inner layer medium.

[0082] S401, opening a through slot of a first preset length on a circuit board.

[0083] S402, electroplating a metal layer on the sidewall of the through groove.

[0084] S403, remove the metal layers at the two ends of the through groove, retain the first metal layer on the first side wall and the second metal layer on the second side wall of the through groove, so that the first metal layer is connected to the inner first circuit of the circuit board, and the second metal layer is connected to the inner second circuit of the circuit board, to form a side wall coupling groove of the circuit board.

[0085] The contents of the above steps S400 to S403 correspond to the contents of steps S300 to S303 of the previous embodiment. For the specific process, please refer to the records in steps S300 to S303, which will not be repeated in this embodiment.

[0086] S404, removing part of the surface metal of the circuit board by etching, so that the remaining surface metal of the circuit board is not in contact with the metal layer on the side wall of the through groove.

[0087] Part of the surface metal of the circuit board can be removed by pattern transfer and liquid etching to form the groove 34, such as Figure 4Specifically, an upper groove is formed between the first metal layer 331 and the shielding layer 31 located at the top layer of the circuit board, and a lower groove is formed between the first metal layer 331 and the shielding layer 31 located at the bottom layer of the circuit board; an upper groove is formed between the second metal layer 332 and the shielding layer 31 located at the top layer of the circuit board, and a lower groove is formed between the second metal layer 332 and the shielding layer 31 located at the bottom layer of the circuit board. The positions of the four grooves 34 are as shown in FIG. Figure 4 As shown in (b), the function is to disconnect the entire groove wall of the side wall coupling groove from the copper sheet on the surface of the shielding layer 31, thereby achieving insulation between the side wall coupling groove and the shielding layers 31 on the top and bottom layers of the circuit board.

[0088] In this step, Figure 4 As shown in (b), the first metal layer 331 of the side wall coupling groove is connected to the first circuit 36 ​​arranged in the inner layer medium 35 of the circuit board, and the second metal layer 332 of the side wall coupling groove is connected to the second circuit 37 arranged in the inner layer medium 35 of the circuit board. Through the side wall coupling groove, wireless energy transmission between the first circuit 36 ​​and the second circuit 37 can be realized. Figure 4 In (b), the inner dielectric layer 35 includes resin and glass cloth.

[0089] Optionally, the preparation method further comprises:

[0090] The coupling medium is filled in the coupling groove of the side wall of the circuit board, and the coupling medium used is pure resin.

[0091] As another embodiment, the coupling medium in the side wall coupling groove may also be air. Using pure resin or air as the coupling medium of the side wall coupling groove can further reduce the coupling loss between the first line 36 and the second line 37 .

[0092] The preparation method of the circuit board side wall coupling groove of the present embodiment can not only realize wireless energy transmission between different traces in the circuit board through the side wall coupling groove, reducing the coupling loss caused by the alignment deviation of the trace position in the prior art; it can also realize insulation between the side wall coupling groove and the top and bottom shielding layers of the circuit board, thereby ensuring the safety of the circuit board.

[0093] In one embodiment, a side wall coupling groove of a circuit board is provided, such as Figure 3 (c) as shown, including:

[0094] The circuit board includes two shielding layers 31 (a first shielding layer and a second shielding layer, Figure 3 (c) shows only the first shielding layer), and an inner layer medium (not shown in the figure) arranged between the first shielding layer and the second shielding layer, wherein a first circuit (not shown in the figure) and a second circuit (not shown in the figure) are arranged in the inner layer medium.

[0095] It also includes: a through slot 32 of a first preset length opened on the circuit board, a first metal layer 331 electroplated on the first side wall of the through slot 32, a second metal layer 332 electroplated on the second side wall of the through slot 32, the first metal layer 331 connected to the first circuit, and the second metal layer 332 connected to the second circuit.

[0096] Optionally, the distance between the first side wall and the second side wall of the through slot is a first set distance.

[0097] Optionally, the coupling medium filled in the side wall coupling groove is pure resin or air.

[0098] Optionally, the first metal layer and the second metal layer are formed by performing secondary milling on two ends of the through slot to remove the metal layers at the two ends.

[0099] The coupling area formula for forming the sidewall coupling groove is:

[0100] S=H*(L-a1-a2)

[0101] Among them, S is the coupling area of ​​the side wall coupling groove, H is the preset thickness of the circuit board, L is the first preset length, a1 is the second preset length of the secondary milling groove at one end of the through groove, and a2 is the third preset length of the secondary milling groove at the other end of the through groove.

[0102] The sidewall coupling groove of this embodiment is formed by opening a through groove on the circuit board, and metallizing the sidewall after two groove milling to obtain a first metal layer and a second metal layer. The first metal layer is used to connect the first circuit, and the second metal layer is used to connect the second circuit, so as to realize wireless energy transmission between different lines in the circuit board through the sidewall coupling groove, and reduce the coupling loss caused by alignment deviation of the line position in the prior art. In addition, the intermediate coupling medium between the first metal layer and the second metal layer is air or pure resin, which can effectively reduce the coupling loss caused by using glass cloth as a coupling medium in the prior art.

[0103] In one embodiment, a side wall coupling groove of a circuit board is provided, such as Figure 4 (a) and Figure 4 As shown in (b), the side wall coupling groove and Figure 3 The difference between the sidewall coupling groove in (c) is that:

[0104] In this embodiment, the two shielding layers 31 of the side wall coupling groove do not contact the first metal layer 331 and the second metal layer 332; an upper groove is formed between the first metal layer 331 and the shielding layer 31 located at the top layer of the circuit board, and a lower groove is formed between the first metal layer 331 and the shielding layer 31 located at the bottom layer of the circuit board; an upper groove is formed between the second metal layer 332 and the shielding layer 31 located at the top layer of the circuit board, and a lower groove is formed between the second metal layer 332 and the shielding layer 31 located at the bottom layer of the circuit board. The positions of the four grooves 34 are as shown in FIG. Figure 4 As shown in (b), the function is to disconnect the entire groove wall of the side wall coupling groove from the copper sheet on the surface of the shielding layer 31, thereby achieving insulation between the side wall coupling groove and the shielding layers 31 on the top and bottom layers of the circuit board.

[0105] The sidewall coupling groove of this embodiment is realized by opening a through groove on the circuit board and metallizing the sidewall after milling the groove, which enables wireless energy transmission between different wirings in the circuit board through the sidewall coupling groove, thereby reducing the coupling loss caused by the alignment deviation of the wiring position in the prior art. In addition, insulation between the sidewall coupling groove and the shielding layer of the circuit board is realized.

[0106] In one embodiment, a circuit board is provided, on which the side wall coupling groove in any of the above embodiments is disposed.

[0107] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A side wall coupling groove of a circuit board, characterized in that: include: The circuit board comprises a first shielding layer, a second shielding layer, and an inner layer medium arranged between the first shielding layer and the second shielding layer, wherein a first circuit and a second circuit are arranged in the inner layer medium; A through slot of a first preset length is opened on the circuit board, a first side wall of the through slot is electroplated with a first metal layer, a second side wall of the through slot is electroplated with a second metal layer, the first metal layer is connected to the first circuit, and the second metal layer is connected to the second circuit; The side wall coupling groove is used to realize wireless energy transmission between the first circuit and the second circuit in the circuit board.

2. The side wall coupling groove of the circuit board according to claim 1, characterized in that: The distance between the first side wall and the second side wall of the through slot is a first set distance.

3. The side wall coupling groove of the circuit board according to claim 1, characterized in that: The coupling medium filled in the side wall coupling groove is pure resin or air.

4. The side wall coupling groove of the circuit board according to claim 1, characterized in that: The first metal layer and the second metal layer are formed by performing secondary milling on the two ends of the through slot to remove the metal layers at the two ends.

5. The side wall coupling groove of the circuit board according to claim 4, characterized in that: The coupling area formula for forming the sidewall coupling groove is: S=H*(L-a1-a2) Among them, S is the coupling area of ​​the side wall coupling groove, H is the preset thickness of the circuit board, L is the first preset length, a1 is the second preset length of the secondary milling groove at one end of the through groove, and a2 is the third preset length of the secondary milling groove at the other end of the through groove.

6. A method for preparing a circuit board side wall coupling groove, characterized in that: The following steps are involved: A circuit board is provided, the circuit board comprising a first shielding layer, a second shielding layer, and an inner layer medium arranged between the first shielding layer and the second shielding layer, wherein a first circuit and a second circuit are arranged in the inner layer medium; A through slot of a first preset length is provided on the circuit board; Electroplating a metal layer on the sidewall of the through groove; Removing the metal layers at the two ends of the through slot, retaining the first metal layer on the first side wall and the second metal layer on the second side wall of the through slot, so that the first metal layer is connected to the first circuit, and the second metal layer is connected to the second circuit, to form a side wall coupling slot of the circuit board; The side wall coupling groove is used to realize wireless energy transmission between the first circuit and the second circuit in the circuit board.

7. The method for preparing the circuit board side wall coupling groove according to claim 6, characterized in that: The “opening a through slot of a first preset length on the circuit board” includes: During the process of forming the through groove, the distance between two side walls of the through groove is controlled to be a first set distance.

8. The method for preparing the circuit board side wall coupling groove according to claim 6, characterized in that: The “removing the metal layers at the two ends of the through slot” includes: A secondary milling groove is performed at one end of the through slot with a second preset length, and a secondary milling groove is performed at the other end of the through slot with a third preset length, and the second preset length and the third preset length are equal or different, so as to remove the metal layer at the two ends.

9. The method for preparing the circuit board side wall coupling groove according to claim 8, characterized in that: After the secondary milling, the preparation method further comprises: Part of the surface metal of the first shielding layer and the second shielding layer is removed by etching, so that the remaining surface metal of the first shielding layer and the second shielding layer is not in contact with the metal layer on the side wall of the through groove.

10. A circuit board, characterized in that: The circuit board is provided with a side wall coupling groove according to any one of claims 1-5.

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