Circuit board and manufacturing method thereof

Abstract

A circuit board and a manufacturing method thereof. The method forms the circuit board by laminating a GCPW structure and an absorbing composite structure. The GCPW structure includes a first single-sided board and a double-sided board. The first single-sided board includes a second surface and two side surfaces. The double-sided board includes two sets of first absorbing units and signal lines. By covering the double-sided board on the second surface and the two side surfaces of the first single-sided board, the two sets of first absorbing units are respectively located on the two side surfaces of the first single-sided board, and the signal lines are located on the second surface. At the same time, the absorbing composite structure is located on the side of the signal lines away from the second surface. The manufacturing method of the circuit board provided by the present invention sets metamaterial structures in three directions of the signal lines, effectively increasing the absorption range of electromagnetic waves, thereby reducing the gain value of signal transmission. The structure design has strong flexibility, the process is simple, the requirements for equipment are low, it is easy to implement, and the manufacturing cost is low.

Description

Technical Field

[0001] The present application relates to a printed circuit board technology, and in particular to a circuit board and a manufacturing method thereof. Background Art

[0002] With the commercialization of 5G millimeter waves, it is necessary to develop a transmission line that cooperates with a 5G millimeter wave antenna. In order to establish a millimeter wave transmission line with a large bandwidth, a grounded coplanar waveguide (GCPW) structure is usually used for circuit design.

[0003] The gain value of the transmission line for a 5G millimeter wave antenna needs to be less than -60 dB. The traditional method for reducing the gain value of a strip antenna is to coat a shielding layer outside the transmission line to prevent the electromagnetic waves inside the transmission line from leaking. However, this method is not applicable to the GCPW structure, mainly because coating a shielding layer outside the GCPW structure will form a cavity, and the electromagnetic waves inside will reflect when hitting the metal layer of the shielding layer. The reflected electromagnetic waves will cancel out the 5G millimeter waves and narrow the bandwidth. Summary of the Invention

[0004] In view of this, in order to overcome at least one of the above defects, it is necessary to provide a manufacturing method of a circuit board.

[0005] In addition, the present application also provides a circuit board manufactured by the above manufacturing method.

[0006] The present application provides a manufacturing method of a circuit board, including the steps of: providing a GCPW structure, the GCPW structure including a first single-sided board and a double-sided board disposed on the surface of the first single-sided board, the first single-sided board including a first dielectric layer and a first metal layer, the first dielectric layer including a first surface, a second surface disposed opposite to the first surface, and two side surfaces connecting the first surface and the second surface, the first metal layer being disposed on the first surface, the double-sided board including a second dielectric layer, two groups of first wave-absorbing units disposed on the surface of the second dielectric layer close to the first single-sided board, and a circuit layer disposed on the surface of the second dielectric layer far from the first single-sided board, the two groups of first wave-absorbing units being buried in the first dielectric layer within the area of the two side surfaces, the circuit layer being disposed corresponding to the second surface, and the circuit layer being electrically connected to the first metal layer; and disposing and pressing a wave-absorbing composite structure on the side of the circuit layer far from the second surface, so as to obtain the circuit board.

[0007] In some possible embodiments, the manufacturing method of the GCPW structure includes the following steps: providing the first single-sided panel; disposing a second single-sided panel on the second surface, the second single-sided panel including a first base layer and two sets of the first wave-absorbing units disposed on one surface of the first base layer; bending and pressing the second single-sided panel so that the two sets of the first wave-absorbing units are buried in the first dielectric layer within the regions of the two side surfaces respectively; disposing a third single-sided panel on one surface of the first base layer away from the first wave-absorbing units, the third single-sided panel including a second base layer close to the first base layer and the circuit layer disposed on one surface of the second base layer away from the first base layer, the circuit layer including a signal line and metal lines disposed on opposite sides of the signal line; and bending and pressing the third single-sided panel so that the signal line is disposed corresponding to the second surface, the metal lines are disposed corresponding to the second surface and the two side surfaces, and are in contact with the first metal layer on the two side surfaces, and the first base layer and the second base layer form the second dielectric layer, thereby obtaining the GCPW structure.

[0008] In some possible embodiments, the manufacturing method of the GCPW structure includes the following steps: providing the first single-sided panel; disposing the double-sided panel on the second surface; and bending and pressing the double-sided panel so that the two sets of the first wave-absorbing units are buried in the first dielectric layer within the regions of the two side surfaces respectively, the circuit layer includes a signal line disposed corresponding to the second surface and metal lines disposed on opposite sides of the signal line, and the metal lines are electrically connected to the first metal layer, thereby obtaining the GCPW structure.

[0009] In some possible embodiments, after bending and pressing the double-sided panel, the manufacturing method of the GCPW structure further includes: forming a through hole through the first dielectric layer, the second dielectric layer and the metal lines; and forming a conductive column in the through hole, and the conductive column electrically connects the metal lines and the first metal layer.

[0010] In some possible embodiments, after bending and pressing the double-sided panel, the manufacturing method of the GCPW structure further includes: forming a third metal layer on the surface of the second dielectric layer away from the side surface, and the third metal layer electrically connects the metal lines and the first metal layer.

[0011] In some possible embodiments, the wave-absorbing composite structure includes a third dielectric layer, a plurality of second wave-absorbing units disposed on the surface of the third dielectric layer close to the double-sided panel, and a second metal layer disposed on the surface of the third dielectric layer away from the double-sided panel.

[0012] In some possible embodiments, the first wave-absorbing unit is a triple split-ring resonator.

[0013] The present application also provides a circuit board, which includes a GCPW structure and an absorbing composite structure arranged in a stacked manner. The GCPW structure includes a first single-sided board and a double-sided board. The first single-sided board includes a first dielectric layer and a first metal layer. The first dielectric layer includes a first surface, a second surface opposite to the first surface, and two side surfaces connecting the first surface and the second surface. The first metal layer is disposed on the first surface. The double-sided board is disposed on the second surface and extends to the two side surfaces. The double-sided board includes a second dielectric layer, two groups of first absorbing units disposed on the surface of the second dielectric layer close to the first single-sided board, and a circuit layer disposed on the surface of the second dielectric layer far from the first single-sided board. The two groups of first absorbing units are buried in the first dielectric layer in the area of the two side surfaces. The circuit layer is disposed corresponding to the second surface and is electrically connected to the first metal layer. The absorbing composite structure is disposed on the side of the circuit layer far from the second surface.

[0014] In some possible embodiments, the double-sided board includes a second single-sided board and a third single-sided board arranged in a stacked manner. The second single-sided board includes a first base layer and two groups of the first absorbing units disposed on one surface of the first base layer. The third single-sided board includes a second base layer close to the first base layer and the circuit layer disposed on the surface of the second base layer far from the first base layer. The circuit layer includes a signal line and metal lines disposed on opposite sides of the signal line. The signal line is disposed corresponding to the second surface. The metal lines are disposed corresponding to the second surface and the two side surfaces, and are in contact with the first metal layer on the two side surfaces. The first base layer and the second base layer constitute the second dielectric layer.

[0015] In some possible embodiments, the GCPW structure further includes a through hole penetrating the first dielectric layer, the second dielectric layer, and the circuit layer. A conductive column is disposed in the through hole, and the conductive column electrically connects the circuit layer and the first metal layer.

[0016] In some possible embodiments, a third metal layer is disposed on the surface of the second dielectric layer far from the side surface, and the third metal layer electrically connects the circuit layer and the first metal layer.

[0017] In some possible embodiments, the first absorbing unit is a triple split-ring resonator.

[0018] In some possible embodiments, the absorbing composite structure includes a third dielectric layer, a plurality of second absorbing units disposed on the surface of the third dielectric layer close to the double-sided board, and a second metal layer disposed on the surface of the third dielectric layer far from the double-sided board.

[0019] Compared with the prior art, the manufacturing method of the circuit board in this application effectively increases the absorption range of electromagnetic waves and then reduces the gain value of signal transmission by adding two groups of second wave-absorbing units to the side of the cavity of the GCPW structure and combining with the first wave-absorbing unit. The structure of the circuit board is simple, and the purpose of reducing the gain value can be achieved through various structural designs, with stronger flexibility, simple process, lower requirements for equipment, easy to implement, and low manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic structural diagram of a circuit board provided by an embodiment of this application.

[0021] Figure 2 It is a gain simulation test diagram of a circuit board provided by an embodiment of this application.

[0022] Figure 3 It is a schematic structural diagram of a circuit board provided by another embodiment of this application.

[0023] Figure 4 It is a schematic structural diagram of the wave-absorbing unit provided by this application.

[0024] Figure 5 For Figure 4 the equivalent circuit diagram of the provided wave-absorbing unit.

[0025] Figure 6 It is a schematic structural diagram of a circuit board provided by another embodiment of this application.

[0026] Figure 7 It is a schematic structural diagram of a circuit board provided by another embodiment of this application.

[0027] Figure 8 It is a schematic structural diagram of the first single-sided board provided by an embodiment of this application.

[0028] Figure 9 It is a schematic structural diagram of the first single-sided copper clad board provided by an embodiment of this application.

[0029] Figure 10 It is a schematic structural diagram of the second single-sided copper clad board provided by an embodiment of this application.

[0030] Figure 11 It is a cross-sectional view of the second single-sided board provided by an embodiment of this application.

[0031] Figure 12 It is a top view of the second single-sided board provided by an embodiment of this application.

[0032] Figure 13 It is a cross-sectional view of the third single-sided board provided by an embodiment of this application.

[0033] Figure 14Top view of the third single-sided panel provided by an embodiment of the present application.

[0034] Figure 15 For lamination Figure 8 The first single-sided panel provided, Figure 11 The second single-sided panel provided, and Figure 13 Schematic diagram of the third single-sided panel provided.

[0035] Figure 16 Schematic diagram of the GCPW structure provided by an embodiment of the present application.

[0036] Figure 17 Schematic diagram of the wave-absorbing composite structure provided by an embodiment of the present application.

[0037] Figure 18 For lamination Figure 16 The GCPW structure provided, and Figure 17 Schematic diagram of the wave-absorbing composite structure provided.

[0038] Figure 19 Schematic diagram of a double-sided copper clad laminate provided by the present application.

[0039] Figure 20 Schematic diagram of the double-sided panel provided by an embodiment of the present application.

[0040] Figure 21 For lamination Figure 8 The first single-sided panel provided, and Figure 20 Schematic diagram of the double-sided panel provided.

[0041] Figure 22 For pressing Figure 21 Schematic diagram of the structure after pressing the first single-sided panel and the double-sided panel in

[0042] Figure 23 For forming vias in Figure 22 The first dielectric layer, the second dielectric layer, and the circuit layer provided. Schematic diagram of the structure.

[0043] Figure 24 Schematic diagram of another GCPW structure provided by the present application.

[0044] Figure 25 Schematic diagram of yet another GCPW structure provided by the present application.

[0045] Figure 26 For lamination Figure 17 The wave-absorbing composite structure provided, and Figure 24 Schematic diagram of the GCPW structure provided.

[0046] Figure 27 Schematic diagram of the double-sided panel provided by another embodiment of the present application.

[0047] Figure 28 For laminating Figure 8 a schematic diagram of the first single-sided board provided Figure 27 and the double-sided board provided

[0048] Figure 29 A schematic diagram of another GCPW structure provided by this application

[0049] Figure 30 Laminating Figure 17 a schematic diagram of the absorbing composite structure provided Figure 29 and the GCPW structure provided

[0050] Figure 31 Pressing Figure 30 a schematic diagram of the structure after the absorbing composite structure and the GCPW structure in

[0051] Description of main component symbols

[0052] Circuit boards 100’, 100, 200, 300

[0053] GCPW structures 10’, 10, 10a, 10b

[0054] The first single-sided board 1

[0055] The first dielectric layer 11, 11’

[0056] The first metal layer 12, 13’

[0057] Double-sided boards 2, 7, 8

[0058] The second dielectric layer 21, 71, 81

[0059] The first absorbing unit 22

[0060] The outer open resonator 221

[0061] The middle open resonator 222

[0062] The inner open resonator 223

[0063] The circuit layer 12’, 23, 83

[0064] Signal lines 121’, 231, 831

[0065] Metal lines 122’, 232, 832

[0066] The second single-sided board 2a

[0067] The first base layer 21a

[0068] The third single-sided board 2b

[0069] The second base layer 21b

[0070] The first part 211, 711, 811

[0071] The second part 212, 712, 812

[0072] The third part 213, 713, 813

[0073] The wave - absorbing composite structure 3’, 3

[0074] The third dielectric layer 31’, 31

[0075] The second wave - absorbing unit 32’, 32

[0076] The second metal layer 33’, 33

[0077] The adhesive layer 4

[0078] The through - hole 5

[0079] The conductive post 6

[0080] The third metal layer 9

[0081] The first single - sided copper - clad laminate 20

[0082] The second single - sided copper - clad laminate 30

[0083] The first copper layer 40

[0084] The second copper layer 50

[0085] The double - sided copper - clad laminate 60

[0086] The third copper layer 70

[0087] The following specific embodiments will further illustrate the present invention in conjunction with the above - mentioned drawings. Specific embodiments

[0088] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0089] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments, and are not intended to limit the present invention.

[0090] Please refer to Figure 1, an embodiment of the present application provides a circuit board 100', the circuit board 100' includes a stacked grounded coplanar waveguide (GCPW) structure 10' and an absorbing composite structure 3', wherein the GCPW structure 10' includes a first dielectric layer 11', a circuit layer 12' disposed on the surface of the first dielectric layer 11' close to the absorbing composite structure 3', and a first metal layer 13' disposed on the surface of the first dielectric layer 11' away from the absorbing composite structure 3'. The circuit layer 12' includes a signal line 121' and metal lines 122' located on both sides of the signal line 121', and the metal lines 122' are electrically connected to the first metal layer 13' for grounding. The absorbing composite structure 3' includes a third dielectric layer 31', a plurality of second absorbing units 32' disposed on the surface of the third dielectric layer 31' close to the signal line 121', and a second metal layer 33' disposed on the surface of the third dielectric layer 31' away from the signal line 121'. The absorbing composite structure 3' is used to absorb the electromagnetic waves emitted by the signal line 121' when transmitting signals, prevent electromagnetic wave leakage, and at the same time will not reflect the electromagnetic waves to form a reflected wave interference to the transmitted signal. The circuit board 100' provided by this embodiment can be used to manufacture a millimeter-wave transmission line with a large bandwidth.

[0091] Each of the second absorbing units 32' is a metamaterial structure, specifically a multi-open resonator. Metamaterials refer to periodic materials formed by artificially designing the geometric structure and size of basic constituent elements. Metamaterials can have special electromagnetic responses to electromagnetic waves. The metamaterial structure realizes the regulation and absorption of electromagnetic waves through a resonant structure. Compared with traditional absorbing materials, the thickness of the metamaterial structure is relatively thinner, it can absorb electromagnetic waves in a smaller frequency band, has a larger absorption bandwidth, and a higher absorption frequency. By achieving impedance matching, metamaterials can prevent electromagnetic waves from being reflected on the surface of the material, and allow a large amount of electromagnetic waves to enter the interior of the metamaterial structure. Then, through dielectric loss and electromagnetic resonance loss, the energy of the electromagnetic waves is converted into heat energy and consumed, achieving the purpose of absorbing electromagnetic waves. After the electromagnetic waves enter the interior of the metamaterial structure, they are divided into two parts. One part of the electromagnetic waves that can resonate with the metamaterial structure is absorbed by the metamaterial structure, and the other part of the electromagnetic waves that cannot resonate with the metamaterial structure is consumed in the form of dielectric loss. Therefore, the suppression of electromagnetic radiation by the metamaterial structure is absorption-type rather than reflection-type, which is beneficial to manufacturing a millimeter-wave transmission line with a large bandwidth.

[0092] Gain is often used to measure the signal transmission ability of an antenna. Specifically, it is the ratio of the power density of the signal generated by the actual antenna and an ideal radiation element at the same point in space under the condition of equal input power. Gain quantitatively describes the degree to which the antenna concentrates and radiates the input power and has a close relationship with the radiation pattern. The narrower the main lobe and the smaller the side lobes of the radiation pattern, the higher the gain. The signal line has the function of conducting signals, and the smaller the gain value, the better. Here, the radiation pattern is applied to the signal line to detect the signal leakage degree of the signal line. A higher gain value indicates serious signal leakage, and a lower gain value indicates slight leakage of the signal line. Therefore, to improve the signal conduction function of the signal line, it is necessary to minimize the gain value. However, from Figure 2 the gain simulation diagram at 30 GHz in [reference] and the gain simulation results in Table 1, it can be seen that the gain value of the circuit board 100' composed of the absorbing composite structure 3' and the GCPW structure 10' cannot meet the required specifications. On the one hand, the reason may be that the number of the second absorbing units 32' is insufficient, resulting in low absorption efficiency; on the other hand, it may be because the side of the cavity jointly formed by the signal line 121' of the GCPW structure 10', the metal lines 122' on both sides of the signal line 121', and the first metal layer 13' is a metal layer (such as a copper layer), which may cause electromagnetic waves to be reflected, thereby forming a reflected wave interference to the transmitted signal and preventing the gain value from being further reduced.

[0093] Table 1

[0094] Wavelength 1 - 40 GHz 30 GHz Gain value <-60dB -20 dB

[0095] Please refer to Figure 3, in order to improve the wave absorption ability of the circuit board 100’, reduce electromagnetic wave reflection, and reduce the gain value, another embodiment of the present application provides a circuit board 100. The circuit board 100 includes a first single-sided board 1, a wave-absorbing composite structure 3, and a double-sided board 2 disposed between the first single-sided board 1 and the wave-absorbing composite structure 3. The first single-sided board 1 includes a first dielectric layer 11 and a first metal layer 12. The first dielectric layer 11 includes a first surface 111 on a side away from the double-sided board 2, a second surface 112 opposite to the first surface 111, and two side surfaces 113 connecting the first surface 111 and the second surface 112. The first metal layer 12 is disposed on the first surface 111. The double-sided board 2 is disposed on the second surface 112 and extends to the two side surfaces 113. The wave-absorbing composite structure 3 is disposed on the surface of the double-sided board 2 away from the second surface 112. The double-sided board 2 includes a second dielectric layer 21, two groups of first wave-absorbing units 22 disposed on the surface of the second dielectric layer 21 close to the first single-sided board 1, and a circuit layer 23 disposed on the surface of the second dielectric layer 21 away from the first single-sided board 1. The two groups of first wave-absorbing units 22 are respectively buried in the first dielectric layer 11 within the regions of the two side surfaces 113. The circuit layer 23 is disposed corresponding to the second surface 112 and is electrically connected to the first metal layer 12. The wave-absorbing composite structure 3 includes a third dielectric layer 31, a plurality of second wave-absorbing units 32 disposed on the surface of the third dielectric layer 31 close to the double-sided board 2, and a second metal layer 33 disposed on the surface of the third dielectric layer 31 away from the double-sided board 2.

[0096] The second dielectric layer 21 includes a first portion 211 disposed on the second surface 112, a second portion 212 disposed on one side surface 113, and a third portion 213 disposed on the other side surface 113. The two groups of first wave-absorbing units 22 are respectively located on the second portion 212 and the third portion 213. The circuit layer 23 includes a signal line 231 and metal lines 232 located on both sides of the signal line 231. The signal line 231 is located on the first portion 211. The metal lines 232 are electrically connected to the first metal layer 12 and are used to achieve grounding.

[0097] The metal lines 232 are located on the first portion 211 and extend to the second portion 212 and the third portion 213. The portions of the metal lines 232 located on the second portion 212 and the third portion 213 are directly electrically connected to the first metal layer 12 to achieve grounding.

[0098] Please refer to Figure 4 With Figure 5, when analyzing the metamaterial structure, the equivalent circuit model theory is usually used. Generally, when designing the metamaterial structure, "split ring resonator" is usually adopted for design, and the size, position and shape of the split ring and the position of the opening are adjusted to obtain the metamaterial structure with the target absorption frequency band. As Figure 4 shown, the first wave absorbing unit 22 is a triple split ring resonator, that is, there are three split rings coupled to each other. The first wave absorbing unit 22 specifically includes an outer split ring resonator 221, a middle split ring resonator 222 and an inner split ring resonator 223 sleeved from outside to inside in sequence. Since the first wave absorbing unit 22 is composed of three split rings, the equivalent circuit model is composed of four series resonance circuits composed of capacitors and inductors. As Figure 5 shown, one path is composed of the first wave absorbing unit 22 and the second dielectric layer 21, and the other three resonance circuits are formed by the mutual coupling of the three split rings of the first wave absorbing unit 22.

[0099] In this embodiment, the second wave absorbing unit 32 has the same structure as the first wave absorbing unit 22 and is also a triple split ring resonator.

[0100] In this embodiment, two groups of the first wave absorbing units 22 are embedded in the first dielectric layer 11, and each group includes two of the first wave absorbing units 22.

[0101] In this embodiment, the material of the first dielectric layer 11 is a thermoplastic resin, specifically a thermoplastic liquid crystal polymer (LCP). The thermoplastic LCP has the characteristic of melting when heated, which can realize the embedding of the first wave absorbing unit 22 in the first dielectric layer 11 during the bending and lamination process of the double-sided board 2 to form an effective metamaterial structure.

[0102] In this embodiment, the materials of the third dielectric layer 31 and the second dielectric layer 21 are both thermoplastic liquid crystal polymer (LCP).

[0103] In this embodiment, the wave absorbing composite structure 3 and the double-sided board 2 are bonded by pressing through an adhesive layer 4.

[0104] In this embodiment, the materials of the first metal layer 12, the second metal layer 32 and the metal line 232 are all copper.

[0105] In this embodiment, the double-sided board 2 includes a second single-sided board 2a and a third single-sided board 2b which are stacked. The second single-sided board 2a includes a first base layer 21a and a first wave-absorbing unit 22 disposed on the surface of the first base layer 21a away from the third single-sided board 2b. The third single-sided board 2b includes a second base layer 21b and the circuit layer 23 disposed on the surface of the second base layer 21b away from the second single-sided board 2a. The first base layer 21a and the second base layer 21b constitute the second dielectric layer 21. Forming the double-sided board 2 by laminating two single-sided boards is conducive to the direct electrical connection between the metal circuit 232 and the first metal layer 12, simplifies the structure of the circuit board 100, has a simple molding process, and is easy to implement.

[0106] In this embodiment, the materials of the first base layer 21a and the second base layer 21b are both thermoplastic liquid crystal polymer (LCP).

[0107] In this embodiment, corresponding to the second part 212 and the third part 213, along the thickness direction of the circuit board 100, the size of the second single-sided board 2a is smaller than that of the third single-sided board 2b. This misalignment design is conducive to the direct contact between the metal circuit 232 and the first metal layer 12 during the lamination process to achieve electrical connection.

[0108] In this application, by adding the double-sided board 2 between the first single-sided board 1 and the wave-absorbing composite structure 3, the first single-sided board 1 and the double-sided board 2 form a GCPW structure 10. Among them, the double-sided board 2 covers the second surface 112 and two side surfaces 113 of the first single-sided board 1, and the circuit layer 23 and the first metal layer 12 enclose a cavity. In this embodiment, a group of the first wave-absorbing units 22 are respectively arranged on both sides of the cavity of the GCPW structure 10, and in combination with the second wave-absorbing unit 32, the absorption range of electromagnetic waves is effectively increased, thereby achieving the purpose of reducing the gain value of the circuit board 100.

[0109] Please refer to Figure 6, Another embodiment of the present application provides a circuit board 200. The difference between the circuit board 200 in this embodiment and the circuit board 100 provided in the foregoing embodiment is that: the second dielectric layer 71 in the double-sided board 7 is an integral structure, and the second dielectric layer 71 includes a first portion 711 corresponding to the second surface 112, and a second portion 712 and a third portion 713 corresponding to the two side surfaces 113. The signal line 231 is disposed on the first portion 711, the metal line 232 is disposed on the first portion 711 and extends to the second portion 712 and the third portion 713, and at the same time, the metal line 232 is not in direct contact with the first metal layer 12. The circuit board 200 further includes a through hole 5 penetrating through the first dielectric layer 11 and the second dielectric layer 71, and a conductive column 6 is disposed in the through hole 5. The conductive column 6 is electrically connected to the metal line 232 and the first metal layer 12 to achieve grounding. The double-sided board 7 is formed by a double-sided circuit manufacturing process, which simplifies the process, improves the production efficiency, and is beneficial to cost reduction. Then, the conductive column 6 is used to electrically connect the metal line 232 and the first metal layer 12. The process is simple and easy to implement. The overall structure of the circuit board 200 is simple, which is beneficial to reducing the gain value.

[0110] In this embodiment, the conductive column 6 can be formed by electroplating or by filling and curing a conductive paste.

[0111] Please refer to Figure 7 , Another embodiment of the present application provides a circuit board 300. The difference between the circuit board 300 in this embodiment and the circuit board 100 provided in the foregoing embodiment is that: the second dielectric layer 81 in the double-sided board 8 is an integral structure, and the second dielectric layer 81 includes a first portion 811 corresponding to the second surface 112, and a second portion 812 and a third portion 813 corresponding to the two side surfaces 113. Both the signal line 831 and the metal line in the circuit layer 83 of the double-sided board 8 are located in the first portion 811. The circuit board 300 further includes a third metal layer 9. The third metal layer 9 is disposed on the surface of the second portion 812 of the second dielectric layer 81 away from the side surface 113, and the third metal layer 9 extends to the surfaces of the first metal layer 12 and the second metal layer 32. The third metal layer is electrically connected to the metal line 832, the first metal layer 12, and the second metal layer 32. By electroplating the third metal layer 9, the ground of the metamaterial structure (i.e., the second wave-absorbing unit 32 and the first wave-absorbing unit 22) and the shielding layer of the side wall of the glue layer 4 can be formed simultaneously. While achieving the reduction of the gain value, the structure and forming process of the circuit board 300 are simplified, the production efficiency is improved, and the cost is reduced.

[0112] An embodiment of the present application provides a method for manufacturing the circuit board 100, and the method specifically includes the following steps:

[0113] Step S11, please refer to Figure 8 , provide a first single-sided panel 1, the first single-sided panel 1 includes a first dielectric layer 11 and a first metal layer 12, the first dielectric layer 11 includes a first surface 111, a second surface 112 opposite to the first surface 111, and two side surfaces 113 connecting the first surface 111 and the second surface 112, and the first metal layer 12 is disposed on the first surface 111.

[0114] In this embodiment, the material of the first dielectric layer 11 is a thermoplastic resin, specifically a thermoplastic liquid crystal polymer (LCP).

[0115] In this embodiment, the material of the first metal layer 12 is copper.

[0116] Step S12, please refer to Figure 9 and Figure 10 , provide a first single-sided copper clad laminate 20 and a second single-sided copper clad laminate 30, the first single-sided copper clad laminate 20 includes a first base layer 21a and a first copper layer 40 disposed on one surface of the first base layer 21a, and the second single-sided copper clad laminate 30 includes a second base layer 21b and a second copper layer 50 disposed on one surface of the second base layer 21b.

[0117] In this embodiment, the materials of the first base layer 21a and the second base layer 21b are both thermoplastic resins, specifically thermoplastic liquid crystal polymers (LCP).

[0118] Step S13, please refer to Figure 11 and Figure 12 , pattern the first copper layer 40 to form two groups of first wave-absorbing units 22, thereby obtaining a second single-sided panel 2a.

[0119] In this embodiment, the first wave-absorbing unit 22 is a triple split-ring resonator.

[0120] In this embodiment, the first wave-absorbing unit 22 is formed by processes of film coating, exposure, development, and etching.

[0121] In this embodiment, there are a total of four first wave-absorbing units 22, each group includes two first wave-absorbing units 22, and they are rotationally symmetrically disposed on one surface of the first base layer 21a.

[0122] Step S14, please refer to Figure 13 and Figure 14 , pattern the second copper layer 50 to form a circuit layer 23, thereby obtaining a third single-sided panel 2b.

[0123] The circuit layer 23 includes signal lines 231 and metal lines 232 located on both sides of the signal lines 231. The signal lines 231 are used for transmitting signals, and the metal lines 232 are used for grounding.

[0124] In this embodiment, the circuit layer 23 is formed by processes such as film covering, exposure, development, and etching.

[0125] Step S15, please refer to Figure 15 And Figure 16 , stack the first single-sided board 1, the second single-sided board 2a, and the third single-sided board 2b in sequence, such that the first absorbing unit 22 is disposed close to the second surface 112, the circuit layer 23 is disposed away from the second single-sided board 2a, bend the second single-sided board 2a and the third single-sided board 2b and press them together, so that the two groups of first absorbing units 22 are respectively embedded in the two side surfaces 113, and the metal lines 232 are in contact with the first metal layer 12, thereby obtaining a GCPW structure 10.

[0126] Since both the first base layer 21a and the second base layer 21b are thermoplastic LCPs, they can be melted under heating conditions and have a certain fluidity, which is convenient for bending and pressing with the first single-sided board 1. At the same time, the material of the first dielectric layer 11 is also thermoplastic LCP. Under the conditions of heating and pressurization, the first absorbing unit 22 can be buried in the first dielectric layer 11. In order to better achieve the direct contact between the metal lines 232 and the first metal layer 12, the sizes of the second single-sided board 2a and the third single-sided board 2b need to be designed according to the size of the first dielectric layer 11. For example, along the extension direction perpendicular to the signal lines 231, the cross-section of the first dielectric layer 11 is generally a rectangle. The width of the rectangle corresponding to the second surface 112 is W, the thickness corresponding to the side surface 113 is h1, the thickness of the second single-sided board 2a is h2, and the thickness of the third single-sided board 2b is h3. Then the width of the second single-sided board 2a is equal to W + 2×h1 - 2×h3, and the width of the third single-sided board is equal to W + 2×h1 + 2×h2. In this way, when bending and pressing, the metal lines 232 on the third single-sided board 2b can be docked with the first metal layer 12 to achieve electrical connection.

[0127] After pressing, the first base layer 21a and the second base layer 21b jointly form a second dielectric layer 21. The second dielectric layer 21 includes a first part 211 corresponding to the second surface 112, a second part 212 corresponding to one side surface 113, and a third part 213 corresponding to the other side surface 113. Among them, the signal lines 231 are located in the first part 211, one group of first absorbing units 22 is located in the second part 212, the other group of first absorbing units 22 is located in the third part 213, and the metal lines 232 are located in the first part 211 and extend to the second part 212 and the third part 213.

[0128] Step S16, refer to Figure 17 , provide an absorbing composite structure 3, the absorbing composite structure 3 includes a third dielectric layer 31, a plurality of second absorbing units 32 disposed on one surface of the third dielectric layer 31, and a second metal layer 33 disposed on a surface of the third dielectric layer 31 away from the side of the second absorbing units 32.

[0129] In this embodiment, the second absorbing unit 32 is a triple split-ring resonator.

[0130] In this embodiment, the second absorbing unit 32 is formed by processes of film coating, exposure, development, and etching.

[0131] In this embodiment, the material of the third dielectric layer 31 is a thermoplastic resin, specifically a thermoplastic liquid crystal polymer (LCP).

[0132] In this embodiment, the material of the second metal layer 33 is copper.

[0133] Step S17, refer to Figure 18 , and in combination with referring to Figure 3 , laminate the GCPW structure 10 and the absorbing composite structure 3 and press them together, so that the second absorbing units 32 are disposed close to the signal lines 231, thereby obtaining the circuit board 100.

[0134] In this embodiment, the GCPW structure 10 and the absorbing composite structure 3 are pressed and bonded together through an adhesive layer 4.

[0135] By using the thermoplastic resin, the second single-sided board 2a and the third single-sided board 2b can be conveniently bent and pressed together with the first single-sided board 1 to form the GCPW structure 10, and the first absorbing units 22 are ingeniously buried inside the side surface of the first dielectric layer 11, thereby adding metamaterial structures on both sides of the cavity, which can increase the electromagnetic wave absorption range to achieve the purpose of reducing the gain value. The manufacturing process is simple, without the need for special equipment, easy to implement, beneficial to reducing the manufacturing cost, and moreover, the first absorbing units 22 are buried inside the side surface 113 of the first dielectric layer 11, which can reduce the overall thickness of the circuit board 100, does not occupy too much space, and is beneficial to the thin, light, short, and small of the circuit board 100.

[0136] Another embodiment of the present application provides a manufacturing method of the circuit board 200. The difference between this method and the manufacturing method of the foregoing circuit board 100 lies in the following steps:

[0137] Step S21, refer to Figure 19, a double-sided copper clad laminate 60 is provided. The double-sided copper clad laminate 60 includes a second dielectric layer 71 and two third copper layers 70 provided on opposite two surfaces of the second dielectric layer 71. The second dielectric layer 71 includes a first portion 711 and second portions 712 and third portions 713 located on both sides of the first portion 711.

[0138] Step S22, please refer to Figure 20 , pattern the two third copper layers 70 respectively to form two sets of first absorbing units 22 and a circuit layer 23, thereby obtaining a double-sided board 7.

[0139] In this embodiment, the signal lines 231 in the circuit layer 23 are provided on the first portion 711, and the metal lines 232 in the circuit layer 23 are provided on the first portion 711 and extend to the second portion 712 and the third portion 713.

[0140] In this embodiment, for the forming methods of the first absorbing units 22 and the circuit layer 23, please refer to the forming methods of the foregoing embodiments.

[0141] Step S23, please refer to Figure 21 and Figure 22 , a first single-sided board 1 is provided. The structure of the first single-sided board 1 is the same as that of the first single-sided board 1 in the foregoing embodiments. Stack the first single-sided board 1 and the double-sided board 7 so that the first absorbing units 22 are disposed close to the first single-sided board 1. Bend the double-sided board 7 and press it so that the first portion 711 where the signal lines 231 are located corresponds to the second surface 112, the second portions 712 and the third portions 713 where the two sets of first absorbing units 22 are located correspond to the two side surfaces 113, and the two sets of first absorbing units 22 are respectively buried in the first dielectric layer 11 within the regions of the two side surfaces 113. The metal lines 232 correspond to the second surface 112 and extend to the two side surfaces 113, and the metal lines 232 do not directly contact the first metal layer 12.

[0142] Step S24, please refer to Figure 23 , form a through hole 5 through the first dielectric layer 11, the second dielectric layer 21 and the metal lines 232.

[0143] In this embodiment, the through hole 5 is formed by mechanical drilling or laser drilling.

[0144] Step S25, please refer to Figure 24 , form a conductive post 6 in the through hole 5. The conductive post 6 electrically connects the metal lines 232 and the first metal layer 12, thereby obtaining a GCPW structure 10a.

[0145] In this embodiment, asFigure 24 As shown, the conductive column 6 can be formed by filling and curing conductive paste in the through hole 5.

[0146] In another embodiment, as Figure 25 , the conductive column 6 can also be formed by electroplating copper in the through hole 5.

[0147] Step S25, please refer to Figure 26 , and in combination with Figure 6 , provide an absorbing composite structure 3, the absorbing composite structure 3 has the same structure as that in the foregoing embodiment, stack the absorbing composite structure 3 and the GCPW structure 10a and press them together, so that the second absorbing unit 32 is disposed close to the signal line 231, thereby obtaining the circuit board 200.

[0148] Another embodiment of the present application provides a manufacturing method of the circuit board 300. The difference between this method and the manufacturing method of the foregoing circuit board 200 lies in the following steps:

[0149] Step S31, please refer to Figure 27 , provide a double-sided board 8. The difference between the double-sided board 8 and the double-sided board 7 in the circuit board 100 provided in the foregoing embodiment is that the second dielectric layer 81 in the double-sided board 8 is an integral structure, and the second dielectric layer 81 includes a first portion 811 and second portions 812 and 813 disposed on both sides of the first portion 811. The signal line 831 and the metal lines in the circuit layer 83 in the double-sided board 8 are both located in the first portion 811.

[0150] Step S32, please refer to Figure 28 and Figure 29 , provide a first single-sided board 1. The first single-sided board 1 has the same structure as the first single-sided board 1 provided in the foregoing embodiment. Stack the first single-sided board 1 and the double-sided board 8 and press them together, so that two groups of first absorbing units 22 are respectively buried in the first dielectric layer 11 in the regions of the two side surfaces 113, thereby obtaining a GCPW structure 10b.

[0151] Step S33, please refer to Figure 30 and Figure 31 , provide an absorbing composite structure 3, stack the absorbing composite structure 3 and the GCPW structure 10b and press them together. For the pressing method, please refer to the foregoing method.

[0152] Step S34, please refer to Figure 7, a third metal layer 9 is formed on the surface of the second part 812 of the second dielectric layer 81 away from the side surface 113. The third metal layer 9 extends to the surfaces of the first metal layer 12 and the second metal layer 32, and the third metal layer 9 is electrically connected to the metal line 832, the first metal layer 12 and the second metal layer 32, thereby obtaining the circuit board 300.

[0153] The manufacturing method of the circuit board 300 in this embodiment has a simple preparation process for the double-sided board 8. There is no need for the metal line 832 to be in direct contact with the first metal layer 12, which reduces the operation difficulty of aligning the metal line 832 with the first metal layer 12. At the same time, the third metal layer 9 is formed by surface electroplating to achieve grounding of the metal line 832. The operation is simple, easy to implement, and has a low cost.

[0154] The manufacturing method of the circuit board 100 (200, 300) of the present application effectively increases the absorption range of electromagnetic waves by adding two groups of first wave-absorbing units 22 to the side of the cavity of the GCPW structure 10 (10a, 10b) and combining with the second wave-absorbing unit 32, thereby reducing the gain value of signal transmission. The structure of the circuit board 100 (200, 300) is simple, and the purpose of reducing the gain value can be achieved through various structural designs, with stronger flexibility, simple process, lower requirements for equipment, easy to implement, and low manufacturing cost.

Claims

1. A manufacturing method of a circuit board, characterized in that, Including the steps of: Providing a GCPW structure, the GCPW structure including a first single-sided board and a double-sided board disposed on the surface of the first single-sided board. The first single-sided board includes a first dielectric layer and a first metal layer. The first dielectric layer includes a first surface, a second surface disposed opposite to the first surface, and two side surfaces connected to both the first surface and the second surface. The first metal layer is disposed on the first surface. The double-sided board includes a second dielectric layer, two groups of first absorbing units disposed on the surface of the second dielectric layer close to the first single-sided board, and a circuit layer disposed on the surface of the second dielectric layer far from the first single-sided board. The two groups of first absorbing units are buried in the first dielectric layer within the regions of the two side surfaces. The circuit layer is disposed corresponding to the second surface and is electrically connected to the first metal layer; And Providing and laminating an absorbing composite structure on the side of the circuit layer far from the second surface to obtain the circuit board.

2. The manufacturing method of the circuit board according to claim 1, characterized in that, The manufacturing method of the GCPW structure includes the following steps: Providing the first single-sided board; Providing a second single-sided board on the second surface, the second single-sided board including a first base layer and two groups of the first absorbing units disposed on one surface of the first base layer; Bending and laminating the second single-sided board to bury the two groups of first absorbing units in the first dielectric layer within the regions of the two side surfaces respectively; Providing a third single-sided board on the surface of the first base layer far from the first absorbing units, the third single-sided board including a second base layer close to the first base layer and the circuit layer disposed on the surface of the second base layer far from the first base layer. The circuit layer includes a signal line and metal lines disposed on opposite sides of the signal line; and Bending and laminating the third single-sided board to make the signal line disposed corresponding to the second surface, the metal lines disposed corresponding to the second surface and the two side surfaces, and in contact with the first metal layer on the two side surfaces. The first base layer and the second base layer form the second dielectric layer to obtain the GCPW structure.

3. The manufacturing method of the circuit board according to claim 1, characterized in that, The manufacturing method of the GCPW structure includes the following steps: Providing the first single-sided board; Providing the double-sided board on the second surface; and Bending and laminating the double-sided board to bury the two groups of first absorbing units in the first dielectric layer within the regions of the two side surfaces respectively. The circuit layer includes a signal line disposed corresponding to the second surface and metal lines disposed on opposite sides of the signal line. The metal lines are electrically connected to the first metal layer to obtain the GCPW structure.

4. The manufacturing method of the circuit board according to claim 3, characterized in that, After bending and laminating the double-sided board, the manufacturing method of the GCPW structure further includes: Forming through holes penetrating the first dielectric layer, the second dielectric layer and the metal lines; and Forming conductive posts in the through holes, the conductive posts electrically connecting the metal lines and the first metal layer.

5. The manufacturing method of the circuit board according to claim 3, characterized in that, After bending and laminating the double-sided board, the manufacturing method of the GCPW structure further includes: A third metal layer is formed on the surface of the second dielectric layer away from the side surface, and the third metal layer is electrically connected to the metal line and the first metal layer.

6. The manufacturing method of the circuit board according to claim 1, characterized in that, The absorbing composite structure includes a third dielectric layer, a plurality of second absorbing units disposed on the surface of the third dielectric layer close to the double-sided board, and a second metal layer disposed on the surface of the third dielectric layer away from the double-sided board.

7. The manufacturing method of the circuit board according to claim 1, characterized in that, The first absorbing unit is a triple split-ring resonator.

8. A circuit board, characterized in that, Comprising: The GCPW structure includes: A first single-sided board, the first single-sided board includes a first dielectric layer and a first metal layer, the first dielectric layer includes a first surface, a second surface opposite to the first surface, and two side surfaces connecting the first surface and the second surface, the first metal layer is disposed on the first surface; and A double-sided board, the double-sided board is disposed on the second surface and extends to the two side surfaces, the double-sided board includes a second dielectric layer, two groups of first absorbing units disposed on the surface of the second dielectric layer close to the first single-sided board, and a circuit layer disposed on the surface of the second dielectric layer away from the first single-sided board, the two groups of first absorbing units are buried in the first dielectric layer in the area of the two side surfaces, the circuit layer is disposed corresponding to the second surface and is electrically connected to the first metal layer; and An absorbing composite structure is disposed on one side of the circuit layer away from the second surface.

9. The circuit board according to claim 8, characterized in that, The double-sided board includes a second single-sided board and a third single-sided board stacked, the second single-sided board includes a first base layer and two groups of the first absorbing units disposed on one surface of the first base layer; the third single-sided board includes a second base layer close to the first base layer and the circuit layer disposed on the side surface of the second base layer away from the first base layer, the circuit layer includes a signal line and metal lines disposed on opposite sides of the signal line, the signal line is disposed corresponding to the second surface, the metal lines are disposed corresponding to the second surface and the two side surfaces, and are in contact with the first metal layer at the two side surfaces, the first base layer and the second base layer constitute the second dielectric layer.

10. The circuit board according to claim 8, characterized in that, The GCPW structure further includes a through hole penetrating the first dielectric layer, the second dielectric layer and the circuit layer, and a conductive post is disposed in the through hole, and the conductive post is electrically connected to the circuit layer and the first metal layer.

11. The circuit board according to claim 8, characterized in that, A third metal layer is disposed on the surface of the second dielectric layer away from the side surface, and the third metal layer is electrically connected to the circuit layer and the first metal layer.

12. The circuit board according to claim 8, characterized in that, The absorbing composite structure includes a third dielectric layer, a plurality of second absorbing units disposed on the surface of the third dielectric layer close to the double-sided board, and a second metal layer disposed on the surface of the third dielectric layer away from the double-sided board.

13. The circuit board according to claim 8, wherein, The first absorbing unit is a triple split-ring resonator.

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