CN107819177B - Flexible high-frequency flat wire with multilayer coplanar waveguide thin structure and device thereof - Google Patents
Flexible high-frequency flat wire with multilayer coplanar waveguide thin structure and device thereof Download PDFInfo
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- CN107819177B CN107819177B CN201610819390.4A CN201610819390A CN107819177B CN 107819177 B CN107819177 B CN 107819177B CN 201610819390 A CN201610819390 A CN 201610819390A CN 107819177 B CN107819177 B CN 107819177B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P3/00—Waveguides; Transmission lines of the waveguide type
- H01P3/003—Coplanar lines
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P3/00—Waveguides; Transmission lines of the waveguide type
- H01P3/18—Waveguides; Transmission lines of the waveguide type built-up from several layers to increase operating surface, i.e. alternately conductive and dielectric layers
Abstract
The invention provides a flexible high-frequency flat wire with a multilayer coplanar waveguide thin structure and a device thereof, wherein the flexible high-frequency flat wire can be easily bent, can provide a larger impedance adjusting range and is convenient for impedance control, and the flexible high-frequency flat wire with the multilayer coplanar waveguide thin structure is provided with a signal wiring pattern, a first grounding pattern arranged on the same layer with the signal wiring pattern and at least one layer of second grounding pattern opposite to the signal wiring pattern or the first grounding pattern through a dielectric layer; the second ground pattern is composed of a set of ground segments arranged at predetermined intervals and intersecting the signal wiring pattern, the ground segments each being disconnected from each other and connected to the first ground pattern through vias, respectively. The invention ensures the impedance control level through the optimized configuration of the second grounding segment, is easy to bend and has longer service life.
Description
Technical Field
The invention relates to a flexible high-frequency flat wire adopting a multilayer coplanar waveguide structure and a device thereof, in particular to a flexible high-frequency flat wire adopting a coplanar waveguide thin structure and a device thereof for controlling impedance matching, which can be applied to signal interconnection in various microwave, radio frequency and millimeter wave circuits and devices.
Background
In recent years, more and more wireless terminal devices adopt a low-profile design to enable the thickness of the terminal to be thinner and thinner, but the smaller the diameter of a coaxial transmission line commonly used for connecting and transmitting high-frequency signals is, the larger the signal loss per unit length thereof is, the lower-profile design of the terminal device requires the use of a coaxial line having the smallest diameter as possible, which will increase the signal loss, so that although the conventional coaxial transmission line has an excellent bending advantage, the low-profile structural application required for low-profile is restricted, and thus, the high-frequency signal transmission realized by replacing the coaxial transmission line with a flat Flexible Printed Circuit (FPC) line becomes one of new application trends in the future
In the microwave technology, a common transmission line structure is a Coplanar waveguide (Coplanar waveguide), which can effectively achieve high characteristic impedance, easy grounding, and lower crosstalk compared with other structures such as microstrip lines, and a signal line S and a ground plane G of the Coplanar waveguide are located on the same plane of a dielectric slab, as shown in fig. one, and the characteristic impedance depends on a ratio of a gap G between the signal line S and the ground plane G to a width w of the signal line. Under the condition that the width of a signal line is constant, high characteristic impedance can be effectively realized by increasing a gap G between the signal line and a ground plane, meanwhile, because the signal line S and the ground plane G are in the same plane, grounding can be realized without a Via hole (Via), and lower crosstalk can be easily obtained, however, the coplanar waveguide has a remarkable defect that low characteristic impedance is difficult to realize, mainly because the low impedance requires that the gap G between the signal line S and the ground plane G is narrow, and the gap G with the width lower than 100um is difficult to realize by using the traditional PCB process. Therefore, the lower impedance (50 ohms) required for flexible high frequency flat wires cannot be achieved using conventional coplanar waveguide structures.
On the other hand, considering that the bending operation is frequently performed during use, the flexible high-frequency flat wire has the characteristic of easy bending which is the same as that of a coaxial transmission line on the premise of ensuring that the signal wire is wide enough (providing low loss), the whole ground plane copper-laying structure of the traditional coplanar waveguide cannot meet the requirement of bending performance, and particularly, the multilayer structure is difficult to bend under the condition.
Disclosure of Invention
Based on the above situation, the invention is an innovative improvement aiming at various defects of the traditional coplanar waveguide structure applied to the thin flexible flat wire, provides a new coplanar waveguide thin structure to meet the requirement, and can be regarded as an extension of the traditional coplanar waveguide structure.
An object of the present invention is to provide a flexible high-frequency flat wire and a device thereof capable of realizing a low impedance range and performing impedance matching adjustment with a 50-ohm communication system using a novel thin structure of a coplanar waveguide.
Another object of the present invention is to provide a flexible high frequency flat wire and its device using a novel thin structure of coplanar waveguide, which is easy to bend and has low loss.
It is another object of the present invention to increase the width of the signal trace as much as possible on the basis of controlling the impedance matching, increase the strength of the signal trace, and prevent the signal trace from being broken when the flexible high-frequency flat wire is bent.
In order to achieve the above object, according to one aspect of the present invention, there is provided a flexible high-frequency flat wire of a multi-layered coplanar waveguide thin structure, which has a signal wiring pattern extending in one direction, a first ground pattern disposed in the same layer as the signal wiring pattern and extending in the same direction, and at least one layer of a second ground pattern opposing the signal wiring pattern or the first ground pattern via a dielectric layer, the second ground pattern having a plurality of ground segments arranged at predetermined intervals in the extending direction and intersecting the projection of the signal wiring pattern, the ground segments being disconnected from each other and connected to the first ground pattern through vias, respectively.
According to another aspect of the present invention, there is provided a flexible high-frequency flat wire of a multilayer coplanar waveguide thin structure, comprising a signal wiring pattern extending in one direction, a first ground pattern disposed on the same layer as the signal wiring pattern and extending in the same direction, an upper ground pattern opposed to the signal wiring pattern or the first ground pattern via an upper dielectric layer, and a lower ground pattern opposed to the signal wiring pattern or the first ground pattern via a lower dielectric layer, the layers on which the signal and the first ground pattern are disposed being located between the layers on which the upper ground pattern is disposed and the layers on which the lower ground pattern is disposed, the upper ground pattern and the lower ground pattern each comprising a plurality of upper ground segments disconnected from each other and a plurality of lower ground segments disconnected from each other, the upper ground segments and the lower ground segments being arranged along the extending direction at respective predetermined intervals, at least one of the upper and lower ground segments intersects the signal wiring pattern in projection and is connected to the first ground pattern through a via.
In one embodiment, each upper ground segment is staggered with each lower ground segment in the extending direction.
In one embodiment, the signal wiring pattern and the first ground pattern are configured to form an electrical characteristic of the entire line, and the ground segment has a length not exceeding a quarter of a wavelength corresponding to the highest frequency signal and is used for fine-tuning the electrical characteristic of the entire line.
In one embodiment, the ground segments include at least a long ground segment having a longer length along the extension direction and a short ground segment having a shorter length along the extension direction, the long ground segment being used to adjust an inductive characteristic of the circuit, and the short ground segment being used to adjust a capacitive characteristic of the circuit.
In one embodiment, the upper ground segment is a long ground segment having a long length in the extension direction for adjusting inductance characteristics, and the lower ground segment is a short ground segment having a short length in the extension direction for adjusting capacitance characteristics.
In one embodiment, the ground segments are arranged in a straight line perpendicular to the extending direction of the signal arrangement line pattern and in parallel, and the spacing distance of the ground segments is one tenth of the corresponding wavelength of the highest-frequency signal passing through the ground segments.
In one embodiment, the signal wiring pattern is a single-ended transmission line or a differential transmission line having a predetermined width, and the first ground pattern is a ground conductive foil disposed at the same interval on both sides of the single-ended transmission line or the differential transmission line.
In one embodiment, the ground segment is an elongated conductive foil extending in a length direction.
In one embodiment, the ground segment is a dumbbell-shaped conductive foil having a width at both ends equal to twice the width in the middle.
In one embodiment, at least one of the ground segments is provided with an opening for ensuring that the capacitive properties of the flexible high frequency flat wire along the extension direction are generally constant.
In one embodiment, at least one of the ground segments (which may be the ground segment of the second ground pattern or the upper or lower ground segment) is a mesh structure.
According to another aspect of the present invention, there is provided a device of flexible high frequency flat wire based on the above thin structure of multilayer coplanar waveguide, comprising at least: a flexible high-frequency flat wire with a multilayer coplanar waveguide thin structure,
the connectors are electrically connected to two ends of the flexible high-frequency flat wire of the multilayer coplanar waveguide thin structure; the flexible high-frequency flat wire of the multilayer coplanar waveguide thin structure is in a strip shape extending along a direction, and is provided with a signal wiring pattern conductive foil extending along the direction, a first grounding pattern conductive foil which is arranged on the same layer with the signal wiring pattern conductive foil and extends along the same direction, and at least one layer of second grounding pattern conductive foil which is opposite to the signal wiring pattern conductive foil or the first grounding pattern conductive foil through a dielectric layer, wherein the second grounding pattern conductive foil is composed of a group of grounding segments which are arranged along the extending direction at preset intervals and intersect with the projection of the signal wiring pattern conductive foil, and the grounding segments are mutually disconnected and are respectively connected with the first grounding pattern conductive foil through holes.
In one embodiment, the flexible high-frequency flat wire of the multilayer coplanar waveguide thin-type structure is formed by a multilayer lamination process and at least comprises an upper insulating covering layer, a signal transmission layer, a dielectric layer, a second grounding layer and a lower insulating covering layer, wherein: the signal transmission layer is provided with the signal wiring pattern conductive foil and the first ground pattern conductive foil, is positioned on the upper surface of the dielectric layer, and further comprises a ground mounting part which is connected with the first ground pattern conductive foil from two sides and surrounds the signal pattern conductive foil, and a signal mounting part which is connected with two sides of the signal wiring pattern conductive foil and has a wider width;
the second ground layer is provided with the second ground pattern conductive foil and the ground segment thereof and is positioned on the lower surface of the dielectric layer, and the second ground layer further comprises ground connecting parts positioned on two sides of the second ground pattern conductive foil and signal connecting parts surrounded by the ground connecting parts and arranged in an insulated manner;
the two side ends of the upper insulating covering layer are symmetrically provided with a signal opening and a grounding opening;
the signal mounting part of the signal transmission layer is electrically connected with the signal connecting part of the second ground layer through a first through hole, and the signal connecting end of the connector is connected with the signal mounting part through the signal opening in a welding manner;
the ground mounting part of the signal transmission layer is electrically connected with the ground connection part of the second ground layer through second via holes, the ground section of the second ground pattern conductive foil is respectively and electrically connected with the first ground pattern through two rows of third via holes symmetrical along the central line of the extending direction, and the shell grounding end of the connector is in welded connection with the ground mounting part through the grounding opening.
(effect of the invention)
According to the flexible high-frequency flat wire and the device thereof (hereinafter, referred to as a flat wire and the device thereof) adopting the thin structure of the multilayer coplanar waveguide of the embodiment of the invention, not only can the impedance be adjusted to match the impedance of a 50 ohm communication system by realizing low impedance and high and low impedance in a wide range, but also the stress concentration caused by bending operation can be eliminated, the flexibility which is comparable to that of a coaxial transmission line can be provided, the impedance control is ensured to have good electrical characteristics, the breakage is not easy to occur even under repeated bending, the impedance can also keep a constant and stable value, and the embodiment of the invention has the advantages of simplicity and high efficiency.
Drawings
Fig. 1 is a schematic view illustrating a conventional coplanar waveguide structure.
Fig. 2 is a schematic view showing a typical coplanar waveguide thin structure of the present invention.
Fig. 3 is a diagram showing a high-frequency flat wire according to a first embodiment of the present invention.
Fig. 4 is a front view showing the high-frequency flat wire shown in fig. 3.
Fig. 5 is a bottom view showing the high-frequency flat wire shown in fig. 3.
Fig. 6 is a sectional view showing the structure of fig. 5 taken along the line A-A and placed in the right direction.
FIG. 7 is a schematic bottom view showing still another high-frequency flat wire according to the second embodiment of the present invention.
Fig. 8 is a schematic bottom view showing still another high-frequency flat wire according to a third embodiment of the present invention.
Fig. 9 is a schematic bottom view showing still another high-frequency flat wire according to a fourth embodiment of the present invention.
Fig. 10 is a schematic front view showing still another high-frequency flat wire according to a fifth embodiment of the invention.
Fig. 11 is a sectional view taken along line B-B in fig. 10.
Fig. 12 is a schematic bottom view showing still another high-frequency flat wire according to a sixth embodiment of the present invention.
Fig. 13 is a perspective view showing an assembly in which a high-frequency flat wire of the present invention is applied to a device.
Fig. 14 is an exploded schematic view illustrating fig. 13.
Fig. 15 is a schematic front view illustrating the signal pattern layer in fig. 14.
Fig. 16 is a schematic front view illustrating the second ground pattern layer of fig. 13.
Detailed Description
The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the figures, the size and relative sizes of layers and regions may be exaggerated for clarity. In addition, the lengthwise direction and the extending direction referred to herein are the same direction, and the corresponding dotted line region is referred to with an arrow mark, and preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings.
As described above, since the conventional coplanar waveguide structure shown in fig. 1 is intended to be used for a narrow-section (thin) flat wire, it is impossible to provide a characteristic impedance having a desired range, particularly a low value impedance (such as 50 ohms of a system impedance commonly used in a communication system), for example, when the width of the narrow-section (thin) flat wire is 2mm or less (2 mm), the dielectric plate thickness is 0.05 to 0.10mm, and the gap is 0.1mm or more (a smaller gap width lower than 0.1mm is difficult to manufacture), when the dielectric constant ξ of a general flexible dielectric plate PI material is 3.2, it is calculated that the characteristic impedance is at least greater than 90 ohms, at a high resistance level, 50 ohms cannot be provided, and it is impossible to use, and in case of a multilayer structure configuration, since too many copper foil layers having a certain thickness are laminated together, the hardness of the flat wire is large (although having a certain degree of flexibility), the bendability of the FPC is not necessary to be deteriorated, and it is not necessary to increase the signal breaking loss due to the additional cost that the bending loss of the coaxial signal line is effectively reduced, and the signal breaking loss of the invention is not necessary to be deteriorated.
In view of the above, referring to fig. 2 and fig. 3, a typical two-layer coplanar waveguide thin structure of the present invention is shown, so as to be applied to the narrow-section (thin) FPC occasion, the thin structure of the coplanar waveguide of the present invention introduces the first ground pattern Gnd beside the signal trace Sgn (as shown in fig. 2, the first ground pattern Gnd is provided on both sides of the signal trace Sgn), a second ground pattern (as a main reference ground) having a plurality of ground segments Gnd' arranged at predetermined intervals in the extending direction of the flexible high-frequency flat wire is provided so as to face the layer where the signal trace/first ground pattern is located through the dielectric layer, here, the ground segment Gnd 'is disposed to intersect the extending direction of the signal trace Sgn (in fig. 2, Gnd' and Sgn intersect perpendicularly to each other), and the ground segments Gnd' are each connected to the first ground pattern Gnd through a via hole (via) to form a uniform and complete ground reference.
To achieve this structure in order to achieve the desired goals, the following procedure should be followed. First, the limited, thin cross-sectional physical dimensions of the flat wire, including length and width, are determined, with preference given toIn the embodiment, the total height is not more than 0.3mm, the thickness of the dielectric sheet between the Sgn/Gnd layer and the Gnd' layer is limited to 0.1mm, and the total width of the flat wire cannot exceed 2.0 mm; second, the preliminary characteristic impedance is calculated in a conventional coplanar waveguide structure, regardless of the second ground pattern: presetting the maximum possible signal wire Sgn width Ws, the minimum gap g between the Sgn and the first grounding pattern Gnd and the preset dielectric plate thickness h according to the summarized empirical formula according to the traditional coplanar waveguide structure
Calculating characteristic impedance (or calculating corresponding parameters through inputting a Linecalc tool); third, the ground segment length Lg of the second ground pattern is determined according to the highest frequency to suppress an unnecessary transmission mode: determining the highest frequency used for the flat wire, in the preferred embodiment the highest frequency of transmission is 6GHz, which corresponds to a wavelength of 27.5mm in transmission, and in order to suppress unwanted transmission modes said ground segment length Lg is at least a quarter of the wavelength corresponding to the highest frequency, said ground segment length Lg being preferably set to 5mm in the preferred embodiment; fourthly, according to the impedance of the coplanar waveguide structure and the length Lg of the grounding segment obtained by the calculation, with the characteristic impedance of 50 ohms as a design target, confirming the final gap Gg of the grounding segment (which is smaller than 1/4 of the wavelength corresponding to the highest frequency in the same way), performing radio frequency index simulation on the structure by using HFSS microwave simulation software, and performing fine adjustment on the preset dielectric plate thickness h according to the simulation result to finally achieve the target of 50 ohms characteristic impedance.
According to the thin coplanar waveguide structure described above, on one hand, the electrical characteristics of the signal trace (which can be classified as a single-ended transmission line in the signal wiring pattern) will be mainly affected by the first and second ground patterns around it, and when the width of the signal trace is widened, since the areas of the ground segments themselves are small and they are spaced apart by a certain distance, the area of the overlapping region between the signal trace and the second ground pattern will not be increased, which will not result in an increase in the capacitance of the circuit, and the impedance will not change significantly and thus maintain a good impedance matching effect. Meanwhile, the first grounding pattern not only enables the grounding segments originally separated from each other to be connected in series into an integral ground through the via holes (via), but also can change the distance between the first grounding pattern and the signal wiring pattern according to actual needs, so that the capacitance between the first grounding pattern and the signal wiring pattern is changed, and the impedance matching effect of the whole circuit is further finely adjusted; on the other hand, because the second grounding pattern is the grounding segments which are completely separated and disconnected with each other, and the separation line is perpendicular to the bending direction (namely the length extending direction) of the flat wire, the surface tension of the second grounding pattern when the second grounding pattern is bent is completely eliminated, the problem of stress concentration which often occurs when the whole grounding pattern is bent is completely avoided, the flexibility of the flat wire is increased, and even if the second grounding pattern is repeatedly bent, the wider signal routing of the invention is not easy to generate abnormal fracture risk.
From the above assumptions according to the invention, the following embodiments are listed which are possible:
FIGS. 3 to 6 are views of a flat wire 100 according to a first embodiment of the present invention
Referring to fig. 3 and fig. 4 to 6, the flat wire 100 is a strip-shaped FPC extending along a direction, and includes a signal trace 101 (here, a single-ended transmission line, or a differential transmission line) as a signal wiring pattern, a first ground pattern 102 disposed beside the signal trace 101, a dielectric layer 103, and a second ground pattern 104 including a plurality of ground segments 104a, wherein the first ground pattern 102 has a certain width and is equally spaced on two sides of the signal trace 101, and the first ground pattern 102 and the signal trace 101 have the same extension length. The signal trace 101, the first ground pattern 102, the dielectric layer 103 and the second ground pattern 104 are sequentially laminated and extended in the same direction. The signal trace 101 is formed of a conductive metal foil material, the first ground pattern 102 and the second ground pattern 104 are formed of a conductive metal foil material, and the dielectric layer 103 is formed of a dielectric material such as polyimide.
Further, the layers of the signal trace 101 and the first ground pattern 102 are located on the upper surface layer of the dielectric layer 103, the layer of the second ground pattern 104 is located on the lower surface layer of the opposite dielectric layer 103, and the ground segments 104a of the second ground pattern 104, which are disconnected from each other, are arranged in a straight line along the extending direction at a predetermined interval d, where the ground segments 104a are perpendicular to the signal transmission line 101 (i.e., the extending direction thereof), and of course, the intersecting angle Q of the ground segments 104a and the signal transmission line 101 may be any non-zero angle value (specifically, refer to fig. 8). At least one set of via holes 105 (also called via holes, via) with certain intervals is arranged between the ground segment 104a and the first ground pattern 102 along the extending direction, so that all the ground segments 104a and the first ground pattern 102 form a uniform reference ground together.
The implementation effect is as follows: with the above arrangement, the width of the signal transmission line 101 can be increased while maintaining impedance matching, and referring to fig. 4 and 5, with any two adjacent ground segments 104a as one functional unit F, the flexible circuit board 100 can be viewed as being equally divided into a plurality of identical functional units F, assuming that W1 and W2 represent two different widths of the signal trace 101 (as shown in fig. 4, W2> W1), L, G respectively represent the length and spacing distance of the ground segment 104a, since the size of the capacitance in the transmission line is determined by the area of the overlapping region between the signal trace 101 and the second ground pattern 104 (assuming that the distance d between the first ground pattern 102 and the signal transmission line 101 is constant and the material and thickness of the dielectric layer 103 are constant), only by comparing the area S (S ═ L ═ W) of the overlapping region between the signal trace 101 and the second ground pattern 104 in each functional unit F, when the width of the signal trace 101 is increased from W1 to W2, i.e. Δ W (W2-W1) is increased, at this time, the area of the overlapping region between the signal trace 101 and the second ground pattern 104 is increased by Δ S (L × Δ W), the area range of the functional unit F can be increased, the spacing distance G between the ground segments 104a is increased to the area of the decreased overlapping region to just offset Δ S, and thus the impedance in each functional unit F is kept substantially unchanged; or, the area range of the functional unit F is kept unchanged, the length L of at least one of the ground segments 104 is reduced, and the reduced overlapping area just offsets Δ S, and preferably, when L is set to be W, the total overlapping area of the signal transmission line 101 and the second ground pattern 104 can be kept unchanged only by setting the reduced total Δ L to be Δ W; alternatively, as shown in fig. 7, an opening 106 is disposed in an overlapping area of at least one of the ground segments 104a and the signal transmission line 101, so that the area of the opening 106 is equal to Δ S, which also ensures that the area of the overlapping area of the signal trace 101 and the second ground pattern 104 is kept unchanged. In addition, the distance d between the first ground pattern 102 and the signal trace 101 can be increased to further improve the capacitance and inductance characteristics, and in summary, the width of the signal transmission line 101 can be easily increased by the above various means while maintaining impedance matching, so that not only can a lower insertion loss be obtained, but also the reflection loss will not be increased.
It should be understood that the shape (an embodiment is a rectangular shape, or may be other oval, L-shape, diamond-shape, etc.), the size, and the intersection angle Q between the ground segment 104a and the signal trace may be randomly arranged as required, or an additional ground layer or an adhesive layer, a connection layer, etc. required by other processes may be added as required, so as to also achieve the object of the present invention, specifically, referring to the second embodiment shown in fig. 7, a notch 106 is made in the projection area of the ground segment 104a and the signal line to finely adjust the characteristic impedance, in the third embodiment shown in fig. 8, the intersection angle between the ground segment 104a and the extending direction of the signal trace 101 is an acute angle, and in the fourth embodiment shown in fig. 9, the ground segment 104a is dumbbell-shaped.
It should be noted that, since the second ground pattern 104 is formed by arranging a plurality of ground segments 104a that are separated from each other along the extending direction of the flat wire 100, when the flat wire 100 is bent, there is no concentrated stress between the ground segments 104a, so that the flat wire is more convenient to bend, and since the width of the signal trace 101 is increased, the signal trace 101 is not easily broken by the bending action, thereby further improving the bending life of the flat wire 100.
FIGS. 10 to 11 show a flat wire 200 according to a fifth embodiment of the present invention
Referring to fig. 10 and 11, the flat wire 200 is a strip-shaped FPC extending in one direction, and the material is substantially the same as that of the first embodiment, and includes at least an upper layer ground pattern layer 201, an upper dielectric layer 202, a middle layer as a signal wiring pattern 203, and first ground patterns 204, a lower dielectric layer 205, and a lower ground pattern layer 206 disposed at both sides of the signal wiring pattern, wherein the signal wiring pattern 203 is a single-ended signal transmission line, the upper layer ground pattern layer 201 includes a plurality of upper layer ground segments 201a spaced apart from each other and arranged in the extending direction of the signal wiring pattern 203 at predetermined intervals, the lower layer ground pattern layer 206 includes a plurality of lower layer ground segments 206a spaced apart from each other and arranged in the extending direction of the signal wiring pattern 203 at predetermined intervals, each of the upper layer ground segments 201a and each of the lower layer ground segments 206a are adjacently staggered in the extending direction, and are connected to the first ground patterns 204 through metal conductive vias 207, respectively.
The implementation effect is as follows: different from the first embodiment, the upper dielectric layer 202 and the lower dielectric layer 205 may have different thicknesses, so that the upper ground pattern layer 201 and the lower ground pattern layer 206 have different electrical characteristics (capacitance or inductance) with respect to the signal wiring pattern 203, and the flat wire 200 has more means for adjusting the electrical characteristics than the flexible circuit board 100, and thus has better applicability, in combination with different configurations of the distance between the upper ground pattern layer and the first ground pattern 204.
It is worth noting that staggering each upper ground segment 201a and each lower ground segment 206a two-by-two adjacently along the extension direction may make each ground segment 201a and 206a have a more significant impact on the change of the electrical characteristics of the flat wire 200.
FIG. 12 is a drawing of a flat wire 00 according to a sixth embodiment of the present invention
Referring to fig. 12, a flat wire 300 is a strip-shaped FPC extending in one direction, and unlike the second embodiment, there are two kinds of ground segments having different lengths in the extending direction of the signal wiring pattern 301 or the first ground pattern 302, namely, a long ground segment 303 and a short ground segment 304, the length of the long ground segment 303 in the extending direction is significantly larger than that of the short ground segment 304, obviously, the two kinds of ground segments 303, 304 may be arranged in the upper and lower ground pattern layers in any combination according to different requirements, the long ground segment 303 is designed to mainly serve as an inductance in a transmission line according to the radio frequency transmission theory, for example, the area covered by the signal wiring pattern 301 in the long ground segment 303 may be designed in a mesh, diamond shape or hollowed out manner, and the diamond-shaped structure is shown in this example in fig. 11, the flat wire 300 has a diamond-shaped trace 303a, the diamond-shaped trace 303a and the signal wiring pattern 301 have a longer transverse distance in the extending direction in the overlapping area of the two, so that a larger inductance characteristic is obtained, and the short-circuited ground is designed into a fully grounded layer (solid ground) in a segmented manner to adjust the capacitance characteristic of the circuit, so that different design requirements of the flat wire 300 are met.
It should be noted that a plurality of ground layers may be added in the above embodiments to perform a main electrical characteristic stabilizing function, or to partially improve the electrical characteristics of the circuit, and a ground layer for shielding EMI may also be added.
Obviously, in all the embodiments described above, a part of the ground segment may not be connected to the first ground pattern, and the position and size of the via (via) connecting the first ground pattern and the ground segment may also be adjusted, so as to obtain more effects of improving the electrical characteristics.
< method for producing Flat wire >
The following describes a method of manufacturing a typical example of the flat wire. In the following description, the steps performed in sequence are described, and various steps other than the above steps may be performed in actual manufacturing.
(1) A first step: forming a signal wiring pattern and a first ground pattern
And cutting a groove in a symmetrical manner in the middle on the base conductive foil layer on one surface side of the double-sided conductive laminated board to form the signal wiring pattern conductive foil and the first grounding pattern conductive foil which are spaced from each other, so that the first grounding pattern conductive foils are distributed on two sides of the signal wiring pattern conductive foil at equal intervals.
(2) A second step: forming a ground segment pattern
And performing a chamfering operation on the base conductive foil layer on the other surface side of the double-sided conductive laminated board at a predetermined angle intersecting with the extending direction of the signal wiring pattern to completely cut off the base conductive foil layer and to cut off the base conductive foil layer, thereby forming a plurality of ground segment conductive foils which are parallel to each other and spaced apart from each other by a predetermined distance on the other surface side of the double-sided conductive laminated board.
(3) A third step: laminated single-sided conductive laminate
The conductive layer of the single-sided conductive laminate is processed in a predetermined pattern, and is laminated with the above-described double-sided conductive laminate together with an adhesive layer.
(4) A fourth step: forming a through hole
Through-hole processing is performed on the intermediate product formed as described above by an NC drill, a laser, or the like, and interlayer connection between the first ground pattern layer and the ground segment is performed.
(5) A fifth step: forming a conductive film
The through-hole is partially plated to obtain a via hole (via) for interlayer connection electrically connected to each other after plating.
(5) A sixth step: forming a covering layer to obtain the flexible circuit board
The upper and lower surfaces of the above-described formed product are covered with a protective covering layer, and the portions not covered with the covering layer may be subjected to surface treatment such as electroless gold plating, if necessary. And obtaining the finished flexible circuit board after the processes.
< applications on Flat wire >
An embodiment of the present invention is described in detail below with reference to fig. 13 and 15, which shows an application example of the high-frequency flat wire of a multilayer coplanar waveguide thin structure to a device assembly (hereinafter referred to as a flat wire assembly).
As shown in fig. 13 and 14 in conjunction with fig. 15 and 16, the flat wire assembly 10 includes a flat wire 30 and two connectors 20 soldered to both ends of the flat wire 30, the width of both side end portions extending along the length direction is wider to provide a transition interface for signal input/output, the middle portion is an elongated extension line with a narrower width to transmit signals under the premise of saving space as much as possible, the flat wire 30 is a transmission structure formed by laminating a multi-layer structure and includes an uppermost upper insulating cover layer 31, a signal transmission layer 32, a dielectric layer 33, a second ground layer 34 and a lowermost lower insulating cover layer 35, wherein the signal transmission layer 32 is located on the upper surface of the dielectric layer 33 and includes a signal trace 321 located in the middle, first ground trace patterns 322 symmetrically located on both sides of the signal pattern 321, and a first ground trace pattern 322 connected from both sides of the first ground trace pattern 322A ground mounting portion 322a surrounding the signal pattern trace 321, wherein the first ground pattern trace 321 has signal mounting portions 321a with wider widths at two sides; the second ground layer 34 is located on the lower surface of the dielectric layer 33, and includes ground connection portions 341 located on both sides, signal connection portions 342 surrounded by the ground connection portions 341 and arranged in an insulated manner with the ground connection portions, and a plurality of second ground sections 343 arranged at certain intervals along the extension direction of the flat wire; the upper insulating cover layer 31 is symmetrically provided with a signal opening 311 and three ground openings 312 at both ends.
With further reference to the connection relationship shown by the dotted line portion of fig. 14, the signal mounting portion 321a of the signal transmission layer 32 and the signal connection portion 342 of the second ground layer 34 are electrically connected through the first via 303, and the signal connection end (not explicitly shown) of the connector 20 is solder-connected with the signal mounting portion 321a through the signal opening 311, so as to form a signal transmission channel together with the first ground pattern trace 321; the ground mounting portion 322a of the signal transmission layer 32 is electrically connected to the ground connection portion 341 of the second ground layer 34 through the second via hole 302, the second ground segment 343 is electrically connected to the first ground pattern 322 through two rows of third via holes 301 juxtaposed to two sides of the center line of the extending direction, so as to provide a complete ground reference with a larger impedance range optimized for the first ground pattern trace 321, and a housing ground terminal (not explicitly shown in the figure) of the connector 20 is connected to the ground mounting portion 322a through the three ground openings 312 by soldering, so as to form a complete ground reference three-dimensional structure.
With the above configuration, the flat wire assembly 10 has the advantages of easy bending, controllable impedance, etc.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.
Claims (14)
1. A flexible high-frequency flat wire with a multilayer coplanar waveguide thin structure is characterized by comprising a signal wiring pattern extending along one direction, a first grounding pattern which is arranged on the same layer with the signal wiring pattern and extends along the same direction, and at least one layer of second grounding pattern which is opposite to the signal wiring pattern or the first grounding pattern through a dielectric layer, wherein the second grounding pattern is provided with a plurality of grounding segments which are arranged at preset intervals along the extending direction and intersect with the projection of the signal wiring pattern, and the grounding segments are mutually disconnected and are respectively connected with the first grounding pattern through holes.
2. A flexible high-frequency flat wire of a multilayer coplanar waveguide thin structure, characterized by comprising a signal wiring pattern extending in one direction, a first ground pattern disposed on the same layer as the signal wiring pattern and extending in the same direction, an upper ground pattern opposed to the signal wiring pattern or the first ground pattern via an upper dielectric layer, and a lower ground pattern opposed to the signal wiring pattern or the first ground pattern via a lower dielectric layer, the layers on which the signal wiring pattern and the first ground pattern are disposed being positioned between the layers on which the upper ground pattern is disposed and the layers on which the lower ground pattern is disposed, the upper ground pattern and the lower ground pattern each comprising a plurality of upper ground segments and a plurality of lower ground segments which are disconnected from each other, the upper ground segments and the lower ground segments being arranged along the extending direction at respective predetermined intervals, at least one of the upper and lower ground segments intersects the signal wiring pattern in projection and is connected to the first ground pattern through a via.
3. The flexible high-frequency flat wire of claim 2, wherein each upper ground segment is staggered with each lower ground segment in the extending direction.
4. The flexible high-frequency flat wire of a multilayer coplanar waveguide thin structure as set forth in claim 1 or 2, further comprising at least a third ground layer, said third ground layer being configured with said signal wiring pattern and first ground pattern to form mainly the electrical characteristics of the entire wire, said ground segment having a length not exceeding one quarter of the wavelength corresponding to the highest frequency signal and being used for fine-tuning the electrical characteristics of the entire wire.
5. The flexible high-frequency flat wire of claim 1 or 2, wherein the ground segment comprises at least a long ground segment with a long length along the extension direction and a short ground segment with a short length along the extension direction, the long ground segment is used for adjusting the inductance characteristic of the circuit, and the short ground segment is used for adjusting the capacitance characteristic of the circuit.
6. The flexible high-frequency flat wire of multilayer coplanar waveguide thin structure as defined in claim 2, wherein the upper grounding segment is a long grounding segment with a long length along the extension direction for adjusting inductance characteristic, and the lower grounding segment is a short grounding segment with a short length along the extension direction for adjusting capacitance characteristic.
7. The flexible high-frequency flat wire of a multilayer coplanar waveguide thin structure as claimed in claim 1 or 2, wherein the grounding segments are arranged in a straight line perpendicular to the extending direction of the signal layout line pattern and in parallel, and the spacing distance of the grounding segments is one tenth of the corresponding wavelength of the highest frequency signal passing through the grounding segments.
8. The flexible high-frequency flat wire of a multilayer coplanar waveguide thin structure as set forth in claim 1 or 2, wherein the signal wiring pattern is a single-ended transmission line or a differential transmission line having a predetermined width, and the first ground pattern is a ground conductive foil disposed at the same interval on both sides of the single-ended transmission line or the differential transmission line.
9. The flexible high-frequency flat wire with the thin multilayer coplanar waveguide structure as claimed in claim 1 or 2, wherein the grounding segment is an elongated conductive foil extending along the length direction.
10. The flexible high-frequency flat wire with the thin multilayer coplanar waveguide structure as claimed in claim 1 or 2, wherein the grounding segment is a dumbbell-shaped conductive foil, and the width of the dumbbell-shaped conductive foil at two ends is equal to twice the width of the dumbbell-shaped conductive foil at the middle.
11. The flexible high-frequency flat wire of a multilayer coplanar waveguide thin structure as claimed in claim 1 or 2, wherein at least one of the grounding segments is provided with an opening for ensuring that the capacitance characteristic of the flexible high-frequency flat wire along the extending direction is kept unchanged.
12. The flexible high-frequency flat wire of the thin multilayer coplanar waveguide structure as claimed in claim 1 or 2, wherein at least one of the grounding segments is a mesh structure.
13. A device of flexible high-frequency flat wire with a thin structure of multilayer coplanar waveguide is characterized by at least comprising:
a flexible high-frequency flat wire with a multilayer coplanar waveguide thin structure,
the connectors are electrically connected to two ends of the flexible high-frequency flat wire of the multilayer coplanar waveguide thin structure;
the flexible high-frequency flat wire of the multilayer coplanar waveguide thin structure is in a strip shape extending along a direction, and is provided with a signal wiring pattern conductive foil extending along the direction, a first grounding pattern conductive foil which is arranged on the same layer with the signal wiring pattern conductive foil and extends along the same direction, and at least one layer of second grounding pattern conductive foil which is opposite to the signal wiring pattern conductive foil or the first grounding pattern conductive foil through a dielectric layer, wherein the second grounding pattern conductive foil is composed of a group of grounding segments which are arranged along the extending direction at preset intervals and intersect with the projection of the signal wiring pattern conductive foil, and the grounding segments are mutually disconnected and are respectively connected with the first grounding pattern conductive foil through holes.
14. The apparatus of claim 13, wherein the flexible high-frequency flat wire with multi-layer coplanar waveguide thin structure is formed by a multi-layer lamination process and comprises at least an upper insulating cover layer, a signal transmission layer, a dielectric layer, a second ground layer and a lower insulating cover layer, wherein:
the signal transmission layer is provided with the signal wiring pattern conductive foil and the first ground pattern conductive foil, is positioned on the upper surface of the dielectric layer, and further comprises a ground mounting part which is connected with the first ground pattern conductive foil from two sides and surrounds the signal pattern conductive foil, and a signal mounting part which is connected with two sides of the signal wiring pattern conductive foil and has a wider width;
the second ground layer is provided with the second ground pattern conductive foil and the ground segment thereof and is positioned on the lower surface of the dielectric layer, and the second ground layer further comprises ground connecting parts positioned on two sides of the second ground pattern conductive foil and signal connecting parts surrounded by the ground connecting parts and arranged in an insulated manner;
the two side ends of the upper insulating covering layer are symmetrically provided with a signal opening and a grounding opening;
the signal mounting part of the signal transmission layer is electrically connected with the signal connecting part of the second ground layer through a first through hole, and the signal connecting end of the connector is connected with the signal mounting part through the signal opening in a welding manner;
the ground mounting part of the signal transmission layer is electrically connected with the ground connection part of the second ground layer through second via holes, the ground section of the second ground pattern conductive foil is respectively and electrically connected with the first ground pattern through two rows of third via holes symmetrical along the central line of the extending direction, and the shell grounding end of the connector is in welded connection with the ground mounting part through the grounding opening.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201610819390.4A CN107819177B (en) | 2016-09-10 | 2016-09-10 | Flexible high-frequency flat wire with multilayer coplanar waveguide thin structure and device thereof |
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| CN201610819390.4A CN107819177B (en) | 2016-09-10 | 2016-09-10 | Flexible high-frequency flat wire with multilayer coplanar waveguide thin structure and device thereof |
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| CN107819177B true CN107819177B (en) | 2020-04-03 |
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| CN108550969A (en) * | 2018-05-25 | 2018-09-18 | 深圳市深大唯同科技有限公司 | A kind of tunable dielectric integrated RF transmission line, coupler and feeding network |
| WO2021000075A1 (en) * | 2019-06-29 | 2021-01-07 | 瑞声声学科技(深圳)有限公司 | Transmission line |
| CN111430863A (en) * | 2019-12-16 | 2020-07-17 | 瑞声科技(新加坡)有限公司 | Transmission line and terminal device |
| CN112423467A (en) * | 2020-10-28 | 2021-02-26 | 中国电子科技集团公司第五十五研究所 | Suspended sectional type coplanar waveguide film circuit structure |
| CN117497990B (en) * | 2024-01-02 | 2024-03-08 | 上海安其威微电子科技有限公司 | Slow wave delay line and chip |
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