Circuit board structure and electronic device

Abstract

The present disclosure provides a circuit board structure and an electronic device, wherein the circuit board structure comprises: a first dielectric layer, a first spiral conductive wire is arranged on the first dielectric layer; a ground plane layer is located below the first dielectric layer, and the ground plane layer is in contact with the first dielectric layer, the ground plane layer and the first spiral conductive wire are isolated by the first dielectric layer; a second dielectric layer is located below the ground plane layer, and the second dielectric layer is in contact with the ground plane layer; a second spiral conductive wire is arranged below the second dielectric layer, and the second spiral conductive wire and the ground plane layer are isolated by the second dielectric layer; wherein the spiral direction of the first spiral conductive wire is one of clockwise direction or counterclockwise direction, and the spiral direction of the second spiral conductive wire is the other of clockwise direction or counterclockwise direction, so that the electromagnetic field directions generated by the first spiral conductive wire and the second spiral conductive wire are consistent.

Description

Technical Field

[0001] This disclosure relates to the field of circuit board technology, and more particularly to a circuit board structure and an electronic device. Background Technology

[0002] Spiral traces on PCBs (Printed Circuit Boards) are a common routing method that reduces electromagnetic interference and improves signal transmission quality. Currently, the top and bottom spiral traces on PCBs are routed in the same spiral direction. This routing method results in low high-frequency insertion loss and a relatively high cutoff frequency. While increasing the number of spiral coils can improve insertion loss characteristics, this requires more PCB space, and longer traces can negatively impact signal transmission quality. Utility Model Content

[0003] This disclosure provides a circuit board structure and an electronic device to at least solve the above-mentioned technical problems existing in the prior art.

[0004] According to a first aspect of this disclosure, a circuit board structure is provided, wherein the circuit board structure includes: A first dielectric layer, on which a first helical wire is disposed; A ground plane layer is located below the first dielectric layer and is in contact with the first dielectric layer. The ground plane layer and the first helical wire are isolated through the first dielectric layer. The second dielectric layer is located below the ground plane layer and is in contact with the ground plane layer; A second helical conductor is disposed below the second dielectric layer, and the second helical conductor and the ground plane layer are isolated by the second dielectric layer; wherein, the helical direction of the first helical conductor is either clockwise or counterclockwise, and the helical direction of the second helical conductor is either clockwise or counterclockwise, so that the electromagnetic fields generated by the first helical conductor and the second helical conductor are in the same direction.

[0005] In one embodiment, the first helical wire includes a first lead wire and a first helical region that are interconnected; The second helical conductor includes a second lead-out conductor and a second helical region that are interconnected; In a direction perpendicular to the ground plane layer, the first spiral region and the second spiral region have an overlapping portion, so that the electromagnetic fields generated by the first spiral conductor and the second spiral conductor are superimposed; The ground plane layer is provided with holes that penetrate the ground plane layer; In a direction perpendicular to the ground plane layer, the shadow of the hole at least covers the shadow of the overlapping portion of the first spiral region and the second spiral region to improve the insertion loss of the circuit board structure and reduce the cutoff frequency.

[0006] In one possible implementation, it further includes: a signal via, the signal via penetrating the first helical conductor, the first dielectric layer, the ground plane layer, the second dielectric layer, and the second helical conductor; the first helical conductor and the second helical conductor communicate with each other through the signal via.

[0007] In one embodiment, the first helical wire and the second helical wire have the same number of helical turns, wire width, wire length, and distance between adjacent wires.

[0008] In one embodiment, the number of turns of the first helical wire and the second helical wire ranges from 5 to 8 turns.

[0009] In one embodiment, the wire widths of the first helical wire and the second helical wire range from 5 to 25 mils.

[0010] In one possible implementation, the distance between adjacent conductors in the first helical conductor and the second helical conductor ranges from 1 to 10 mils.

[0011] In one embodiment, the dielectric constants of the first dielectric layer and the second dielectric layer are 4.2 to 4.8.

[0012] In one embodiment, the first lead wire extends along a first direction, and the second lead wire extends along either the first direction or a second direction, wherein the second direction intersects with the first direction.

[0013] According to a second aspect of this disclosure, an electronic device is provided, including a circuit board structure as described in any of the above embodiments.

[0014] The circuit board structure and electronic device disclosed herein, by setting the spiral directions of the first and second spiral wires of the upper and lower layers to opposite spiral directions, make the electromagnetic field directions generated by the upper and lower spiral wires consistent. The superposition of electromagnetic fields increases the high-frequency impedance, thereby greatly improving the high-frequency insertion loss and reducing the cutoff frequency while occupying the same space and trace length.

[0015] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0016] The above and other objects, features, and advantages of this disclosure will become readily apparent from the following detailed description of exemplary embodiments, taken in conjunction with the accompanying drawings. Several embodiments of this disclosure are illustrated in the drawings by way of example and not limitation, in which: In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.

[0017] Figure 1 This is a schematic diagram of the circuit board structure provided in an embodiment of the present disclosure; Figure 2 This is a schematic diagram of the structure of the first helical wire provided in an embodiment of this disclosure; Figures 3a to 3d This is a schematic diagram showing various placements of the first and second helical wires in this disclosure; Figure 4 The experimental results curves for circuit board structures under different conditions are shown. Figure 5 The diagram shows the electric field distribution of the circuit board structure under different conditions. Detailed Implementation

[0018] To make the objectives, features, and advantages of this disclosure more apparent and understandable, the technical solutions in the embodiments of this disclosure 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 disclosure, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0019] This disclosure provides a circuit board structure. Figure 1 This is a schematic diagram of the circuit board structure provided in the embodiments of this disclosure, such as... Figure 1 As shown, the circuit board structure includes: A first dielectric layer 21 is provided with a first helical wire 11; The ground plane layer 30 is located below the first dielectric layer 21 and is in contact with the first dielectric layer 21. The ground plane layer 30 and the first helical wire 11 are isolated by the first dielectric layer 21. The second dielectric layer 22 is located below the ground plane layer 30, and the second dielectric layer 22 is in contact with the ground plane layer 30; A second helical conductor 12 is disposed below the second dielectric layer 22, and the second helical conductor 12 and the ground plane layer 30 are isolated by the second dielectric layer 22; wherein, the helical direction of the first helical conductor 11 is either clockwise or counterclockwise, and the helical direction of the second helical conductor 12 is either clockwise or counterclockwise, so that the electromagnetic field generated by the first helical conductor 11 and the second helical conductor 12 is in the same direction.

[0020] The first dielectric layer 21 and the second dielectric layer 22 respectively separate the first helical conductor 11 and the second helical conductor 12 from the ground plane layer 30 to avoid crosstalk between the first helical conductor 11 and the second helical conductor 12 and the ground plane layer 30.

[0021] In one embodiment, the materials of the first dielectric layer 21 and the second dielectric layer 22 can be organic materials, such as organic resins, which can be epoxy resins, polyimide or polytetrafluoroethylene.

[0022] The dielectric constants of the first dielectric layer 21 and the second dielectric layer 22 are 4.2 to 4.8. At these dielectric constants, the cutoff frequency can be reduced more effectively and the insertion loss improved.

[0023] In this embodiment, the helical direction of the first helical conductor 11 is opposite to that of the second helical conductor 12. For example, when the helical direction of the first helical conductor 11 is clockwise, the helical direction of the second helical conductor 12 is counterclockwise, and vice versa. By setting the helical directions of the upper and lower layers of the first and second helical conductors to be opposite, the electromagnetic field directions generated by the upper and lower layers of helical conductors are aligned. The superposition of electromagnetic fields increases the high-frequency impedance, thereby greatly improving the high-frequency insertion loss and reducing the cutoff frequency while occupying the same space and trace length.

[0024] In one embodiment, such as Figure 1 As shown, the first helical wire 11 includes a first lead wire 111 and a first helical region 112 that are interconnected. The second spiral wire 12 includes a second lead wire 121 and a second spiral region 122 that are interconnected. In the direction perpendicular to the ground plane layer 30, the first spiral region 112 and the second spiral region 122 have an overlapping portion, so that the electromagnetic fields generated by the first spiral conductor 11 and the second spiral conductor 12 are superimposed. A hole 31 penetrating the ground plane layer 30 is provided on the ground plane layer 30; In the direction perpendicular to the ground plane layer 30, the shadow of the hole 31 at least covers the shadow of the overlapping portion of the first spiral region 112 and the second spiral region 122, so as to improve the insertion loss of the circuit board structure and reduce the cutoff frequency.

[0025] In this disclosure, by removing at least the ground plane layer 30 corresponding to the overlapping portion of the first spiral region 112 and the second spiral region 122, a hole 31 is formed, which can reduce the coupling capacitance between the trace and the ground plane layer, improve the high-frequency impedance characteristics, thereby improving the high-frequency insertion loss and reducing the cutoff frequency.

[0026] In other embodiments, the shadow of the hole 31 can also completely cover the shadows of the first spiral region 112 and the second spiral region 122 in a direction perpendicular to the ground plane layer 30.

[0027] The first lead wire 111 is the signal input terminal of the first spiral wire 11, and the second lead wire 121 is the signal input terminal of the second spiral wire 12.

[0028] The materials of the first helical wire 11 and the second helical wire 12 include, but are not limited to, copper.

[0029] In one embodiment, the first helical wire 11 and the second helical wire 12 have the same number of helical turns, wire width, wire length, and distance between adjacent wires.

[0030] In this disclosure, by setting the shapes of the first helical wire 11 and the second helical wire 12 to be completely identical except for the helical direction, it is possible to better improve the high-frequency insertion loss and reduce the cutoff frequency.

[0031] In one embodiment, the number of turns of the first helical wire 11 and the second helical wire 12 ranges from 5 to 8 turns.

[0032] The width of the first helical conductor 11 and the second helical conductor 12 ranges from 5 to 25 mils.

[0033] The distance between adjacent conductors in the first helical conductor 11 and the second helical conductor 12 ranges from 1 to 10 mils.

[0034] The number of turns, wire width, and distance between adjacent wires of the first helical wire 11 and the second helical wire 12 are all within their respective ranges, all in order to improve high-frequency insertion loss and reduce cutoff frequency without increasing space and trace length.

[0035] Figure 2 This is a schematic diagram of the structure of the first helical wire provided in an embodiment of this disclosure. It should be noted that the structure of the second helical wire is the same as that of the first helical wire, except that the helical direction is opposite to that of the first helical wire. Figure 2 The first spiral wire shown is the same as the one shown; please refer to it. Figure 2 .

[0036] like Figure 2 As shown, the distance between adjacent conductors in the first helical conductor 11 and the second helical conductor 12 is h1. h1 can refer to the vertical distance between adjacent conductors or the horizontal distance between adjacent conductors.

[0037] In one embodiment, the first lead wire 111 extends along a first direction, and the second lead wire 121 extends along either the first or the second direction, wherein the second direction intersects the first direction.

[0038] Figures 3a to 3d This is a schematic diagram showing various placements of the first and second helical wires in this disclosure.

[0039] like Figure 3a and Figure 3b As shown, the first lead wire 111 and the second lead wire 121 both extend along the first direction.

[0040] like Figure 3c and Figure 3d As shown, the first lead wire 111 extends along the first direction, and the second lead wire 121 extends along the second direction, with the first direction perpendicular to the second direction.

[0041] In some other embodiments, the first lead wire 111 extends along a first direction, and the second lead wire 121 extends along a second direction. The first direction and the second direction form an angle greater than 0 degrees and less than 90 degrees.

[0042] This means that the placement of the first spiral wire 11 and the second spiral wire 12 is not limited, as long as the first spiral region 112 and the second spiral region 112 have overlapping parts, and the overlapping parts coincide with the hole.

[0043] In one embodiment, such as Figure 1 As shown, the circuit board structure also includes a signal via 40, which passes through the first helical conductor 11, the first dielectric layer 21, the ground plane layer 30, the second dielectric layer 22, and the second helical conductor 12; the first helical conductor 11 and the second helical conductor 12 communicate with each other through the signal via 40.

[0044] Figure 4 The figure shows the experimental results curves for the circuit board structure under different conditions. Under conditions S1, S2, and S3, three experimental result curves are obtained respectively. Condition S1 corresponds to the condition where the first and second helical wires have the same helical direction, and there is a hole in the ground plane layer; condition S2 corresponds to the condition where the first and second helical wires have the same helical direction, and there is no hole in the ground plane layer; condition S3 corresponds to the condition where the first and second helical wires have different helical directions, and there is a hole in the ground plane layer.

[0045] like Figure 4 As shown, under condition S1, the insertion loss of the circuit board structure's routing method at 705MHz is -28dB; under condition S2, the insertion loss of the circuit board structure's routing method at 855MHz is -3.5dB; and under condition S3, the insertion loss of the circuit board structure's routing method at 425MHz is -32dB. Figure 4It can be seen that the circuit board structure under the S3 condition has a lower cutoff frequency and a higher insertion loss.

[0046] Figure 5 This shows the electric field distribution of the circuit board structure under different conditions. Figure 5 The three conditions and Figure 4 The three conditions are the same: S1, S2, and S3. For example... Figure 5 As shown, under the condition corresponding to S3, the electric field of the circuit board structure is the largest. The larger the electric field, the greater the current loss when the signal passes through the spiral wire, which means that the insertion loss is greater and the filtering effect of high-frequency signals is better.

[0047] This disclosure also provides an electronic device, including the circuit board structure as described in any of the above embodiments.

[0048] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this disclosure can be achieved, and this is not limited herein.

[0049] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0050] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A circuit board structure, characterized in that, The circuit board structure includes: A first dielectric layer, on which a first helical wire is disposed; A ground plane layer is located below the first dielectric layer and is in contact with the first dielectric layer. The ground plane layer and the first helical wire are isolated through the first dielectric layer. The second dielectric layer is located below the ground plane layer and is in contact with the ground plane layer; A second helical conductor is disposed below the second dielectric layer, and the second helical conductor and the ground plane layer are isolated by the second dielectric layer; wherein, the helical direction of the first helical conductor is either clockwise or counterclockwise, and the helical direction of the second helical conductor is either clockwise or counterclockwise, so that the electromagnetic fields generated by the first helical conductor and the second helical conductor are in the same direction.

2. The circuit board structure according to claim 1, characterized in that, The first helical wire includes a first lead wire and a first helical region that are interconnected; The second helical conductor includes a second lead-out conductor and a second helical region that are interconnected; In a direction perpendicular to the ground plane layer, the first spiral region and the second spiral region have an overlapping portion, so that the electromagnetic fields generated by the first spiral conductor and the second spiral conductor are superimposed; The ground plane layer is provided with holes that penetrate the ground plane layer; In a direction perpendicular to the ground plane layer, the shadow of the hole at least covers the shadow of the overlapping portion of the first spiral region and the second spiral region to improve the insertion loss of the circuit board structure and reduce the cutoff frequency.

3. The circuit board structure according to claim 1, characterized in that, Also includes: A signal via, wherein the signal via penetrates the first helical conductor, the first dielectric layer, the ground plane layer, the second dielectric layer, and the second helical conductor; The first helical wire and the second helical wire communicate with each other through the signal via.

4. The circuit board structure according to claim 1, characterized in that, The first and second spiral wires have the same number of spiral turns, wire width, wire length, and distance between adjacent wires.

5. The circuit board structure according to claim 1, characterized in that, The number of spiral turns of the first spiral wire and the second spiral wire ranges from 5 to 8 turns.

6. The circuit board structure according to claim 1, characterized in that, The width of the first spiral conductor and the second spiral conductor ranges from 5 to 25 mils.

7. The circuit board structure according to claim 1, characterized in that, The distance between adjacent conductors in the first and second helical conductors ranges from 1 to 10 mils.

8. The circuit board structure according to claim 1, characterized in that, The dielectric constants of the first dielectric layer and the second dielectric layer are 4.2 to 4.

8.

9. The circuit board structure according to claim 2, characterized in that, The first lead wire extends along a first direction, and the second lead wire extends along either the first direction or the second direction, wherein the second direction intersects with the first direction.

10. An electronic device, characterized in that, Includes the circuit board structure as described in any one of claims 1-9 above.

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