Transition structure for solderless connector to PCB coplanar waveguide

Abstract

The application discloses a transition structure for a solderless connector and a PCB coplanar waveguide, comprising a top connector structure, a coplanar waveguide upper metal structure, an intermediate layer medium structure and a lower metal structure arranged in sequence from top to bottom; a medium channel and a metal probe are arranged on the top connector structure. The coplanar waveguide upper metal structure comprises a metal disc, an impedance transformer, a metalized via and an intermediate transmission line; wherein the metal disc, the impedance transformer and the intermediate transmission line are connected to form a transmission channel of the coplanar waveguide. The coplanar waveguide intermediate layer medium structure comprises a medium substrate, and the medium substrate is provided with a metalized via. The coplanar waveguide lower metal structure comprises a metal back disc and a metalized via. The transition structure of the scheme can cover a bandwidth of 50 GHz, covering high-frequency applications; and uncontrollable factors such as tin balls in the soldered connector are avoided.

Description

Technical Field

[0001] This invention relates to various microwave communication fields, and in particular to a transition structure for a solderless connector and a coplanar waveguide on a PCB. Background Technology

[0002] Microwave integrated circuits (ICs) are functional circuits operating in the microwave / millimeter-wave band. They consist of passive microwave devices, active microwave devices, and numerous interconnecting transition structures between transmission lines integrated onto a substrate. Planar transmission structures such as microstrip lines, coplanar striplines, and grounded coplanar waveguides are widely used in microwave ICs due to their relative ease of design, fabrication, and integration. These microwave circuits, implemented using PCB technology, typically require RF connectors for connection to other devices or circuits. As the operating frequency requirements of microwave ICs increase, impedance discontinuities at the connection surfaces lead to poor performance at high frequencies. Designers need to design transition structures to compensate for these impedance discontinuities between the connectors and the circuits. Therefore, in high-frequency applications, the transition structure from connectors to other planar transmission lines is a common problem in microwave ICs, and its performance becomes a key factor affecting system characteristics.

[0003] Currently, there are few reports on transition structures between connectors and PCB ground coplanar waveguides. Research on impedance compensation in transition sections mainly focuses on solderable connectors, primarily investigating the effects of solder joints and temperature, with limited optimization schemes and narrow performance coverage. There are no reports on transition structures between solderless connectors and PCB ground coplanar waveguides. Therefore, proposing a transition structure for solderless connectors and PCB ground coplanar waveguides has significant engineering value and importance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a transition structure between a connector and a PCB coplanar waveguide that is solderless and has good transmission performance.

[0005] Therefore, this application provides the following technical solution: a transition structure for a solderless connector and a coplanar waveguide on a PCB, characterized in that it comprises, from top to bottom, a top-layer connector structure, a coplanar waveguide upper metal structure, a coplanar waveguide intermediate dielectric structure, and a coplanar waveguide lower metal structure; wherein, the coplanar waveguide upper metal structure includes an upper ground layer, a metal disk, an impedance transformer, a plurality of first metallized vias located on the upper ground layer, and an intermediate transmission line, wherein the intermediate transmission line is electrically connected to one end of the impedance transformer, and the other end of the impedance transformer is electrically connected to the metal disk; the coplanar waveguide intermediate dielectric structure includes a dielectric substrate and a dielectric substrate disposed on the dielectric substrate. The waveguide includes several second metallized vias; the lower metal structure of the coplanar waveguide includes a lower ground layer, a metal back disk, and several third metallized vias located on the lower ground layer, with the metal back disk located directly below the metal disk; the top connector structure includes a base, a dielectric channel, and a metal probe, with the dielectric channel located on the lower surface of the base and facing the intermediate transmission line, and the metal probe electrically connected to the metal disk in a contact manner; the several first metallized vias, the several second metallized vias, and the several third metallized vias are respectively connected to each other, so that the upper ground layer and the lower ground layer are connected together and together form the signal ground in the coplanar waveguide.

[0006] In the transition structure, the metal back disk in the underlying metal structure of the grounded coplanar waveguide provides impedance compensation, which greatly improves transmission performance. The impedance transformer adjusts the matching performance between the metal disk and the intermediate transmission line, further enhancing the transmission performance of the transition structure, with a bandwidth covering up to 50GHz. Therefore, the solderless connector and PCB coplanar waveguide transition structure designed in this application covers high-frequency applications and has a wide bandwidth coverage. Furthermore, it avoids the influence of uncontrollable factors such as solder balls in soldered connectors, making it easy to manufacture and achieve precise assembly yield.

[0007] In one possible implementation, the metal probe penetrates the base in a vertical direction and makes perpendicular contact with the metal disk. This solution provides a specific design for the metal probe and its connection to the metal disk, featuring a compact structure that is easy to manufacture.

[0008] In one possible implementation, the coplanar waveguide transmission structure formed by the intermediate transmission line, the upper ground layer, the dielectric substrate, and the lower ground layer has an impedance of 50 ohms. This solution provides a specific impedance value for a coplanar waveguide transmission structure that balances advantages in voltage withstand capability, power transmission, and loss.

[0009] In one possible implementation, the metal disk is a disc, and the metal back disk is an annulus. Preferably, in this possible implementation, the diameter of the disc is larger than the great circle diameter of the annulus.

[0010] In one possible implementation, the diameter of the metal disk is 0.2-0.7 mm, and the large circle diameter of the metal back disk is 0.2-0.6 mm, and the small circle diameter is 0.1-0.3 mm.

[0011] The dimensions of the metal backplate and the metal disk provided in this solution can ensure effective impedance compensation for impedance discontinuities between the metal disk and the metal probes in the connector.

[0012] In one possible implementation, the impedance transformer is a metal wire with a linewidth smaller than that of the intermediate transmission line.

[0013] In one possible implementation, the plurality of first metallized vias are evenly spaced and surround the outer side of the intermediate transmission line, the impedance transformer, and the metal disk.

[0014] In one possible implementation, the dielectric constant of the dielectric substrate is selected to be 3.1-3.6.

[0015] In one possible implementation, at least one threaded hole is provided at corresponding positions on the base, upper ground layer, dielectric substrate, and lower ground layer.

[0016] The threaded hole design provided in this solution is easy to manufacture, and the type of threaded fasteners that can be connected to it is easy to select, which has the advantage of saving manufacturing costs. Moreover, since the transition structure uses threaded fasteners to fix the four-layer structure, including the top connector structure and the coplanar waveguide, together, it eliminates the impact of uncontrollable factors such as welding process on performance, causes less damage to PCB products, and enables the reuse of connectors.

[0017] Other specific embodiments and beneficial effects of this application will be described in detail in the following detailed embodiments section. Attached Figure Description

[0018] The accompanying drawings used in the description of the embodiments or prior art are briefly introduced below.

[0019] Figure 1 This is a three-dimensional exploded view of a transition structure provided in one embodiment of this application; Figure 2 This is a schematic diagram of a connector provided in one embodiment of this application; Figure 3 This is a planar structural diagram of the upper metal structure of the grounded coplanar waveguide provided in one embodiment of this application; Figure 4 This is a planar structural diagram of a coplanar waveguide intermediate layer dielectric structure provided in one embodiment of this application; Figure 5 This is a planar structural diagram of the underlying metal structure of the grounded coplanar waveguide provided in one embodiment of this application; Figure 6 This is the impedance matching result under the simulation results of the transition structure provided in one embodiment of this application; Figure 7 This is the insertion loss result under the simulation results of the transition structure provided in one embodiment of this application.

[0020] The components are as follows: 1. Top-layer connector structure; 10. Base; 11. Dielectric channel; 12. Metal probe; 13. Threaded hole; 101. Lower substrate; 102. Upper substrate; 103. Vertical channel; 2. Upper metal structure of coplanar waveguide; 20. Upper ground layer; 21. Metal disk; 22. Threaded hole; 23. Impedance transformer; 24. Metallized via; 25. Intermediate transmission line; 3. Middle dielectric structure of coplanar waveguide; 30. Dielectric substrate; 31. Threaded hole; 32. Metallized via; 4. Lower metal structure of coplanar waveguide; 40. Lower ground layer; 41. Metal back disk; 42. Threaded hole; 44. Metallized via. Detailed Implementation

[0021] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0022] In the description of this application, the terms "middle", "upper", "lower", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0023] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0024] This application discloses a transition structure for a solderless connector and a PCB coplanar waveguide. The top-layer connector structure and the three-layer grounded coplanar waveguide structure are fixedly connected together by fasteners (such as screws), eliminating the influence of uncontrollable factors such as soldering. The transition structure is fed by the grounded coplanar waveguide, which not only has low-loss transmission performance, but also has the characteristics of wide frequency band coverage, and the assembly process requirements are also low.

[0025] Figure 1 A perspective view of a transition structure for a solderless connector and a coplanar waveguide on a PCB, according to an embodiment of the present disclosure, is shown schematically.

[0026] like Figure 1 As shown, the transition structure mainly consists of a top-layer connector structure 1, a coplanar waveguide upper metal structure 2, a coplanar waveguide intermediate dielectric structure 3, and a coplanar waveguide lower metal structure 4. The top-layer connector structure 1 is located on top of the coplanar waveguide upper metal structure 2, while the coplanar waveguide upper metal structure 2 and the coplanar waveguide lower metal structure 4 are located on the upper and lower surfaces of the coplanar waveguide intermediate dielectric structure 3, respectively.

[0027] like Figure 2 The top-level connector structure 1 is a solderless connector structure, the main body of which is a metal structure, including a base 10, a medium channel 11, a metal probe 12 and a pair of threaded holes 13.

[0028] See Figure 1-2 The base 10 includes a plate-shaped lower base 101 and a cylindrical upper base 102. A vertical channel 103 extending in the vertical direction is provided in the middle of the upper base 102, and the vertical channel 103 passes through the lower base 101.

[0029] The dielectric channel 11 is located on the bottom surface of the lower substrate 101, and it has a U-shaped groove structure with the slot facing downwards. This dielectric channel 11 is specifically designed to reserve space for the underlying coplanar waveguide transmission line, and its size is larger than the size of the intermediate transmission line 25 of the upper coplanar waveguide metal structure 2 on the PCB board. The dielectric channel 11 is filled with a non-metallic dielectric, such as air. The base 10 is made of metal, preferably stainless steel.

[0030] A metal probe 12 is disposed within the vertical channel 103. The metal probe 12 is used to transmit radio frequency signals. The metal probe 12 is a metal probe with good conductivity, such as a gold probe, a copper probe, or a platinum probe. In this example, the metal probe 12 is preferably a probe made of gold-plated copper.

[0031] A pair of threaded holes 13 are used to fix the structure to the rest. In this example, the threaded holes 13 are blind holes, located at the bottom surface of the lower base 101 from the opening. The diameter of the threaded holes 13 is preferably 2 mm, and the distance between the pair of threaded holes 13 is preferably set to 7 mm.

[0032] like Figure 3As shown, the upper metal structure 2 of the coplanar waveguide consists of an upper ground layer 20, a metal disk 21, a pair of threaded holes 22, an impedance transformer 23, several metallized vias 24, and an intermediate transmission line 25. The metal disk 21, impedance transformer 23, and intermediate transmission line 25 are electrically connected sequentially to form the transmission channel of the coplanar waveguide. The structure formed by the metal disk 21, impedance matching device 23, and intermediate transmission line 25 is spaced from the upper ground layer 20.

[0033] The metal disk 21 is preferably a disc with a diameter of 0.2-0.7 mm; preferably 0.44 mm. The impedance transformer 23 is a metal wire with a width smaller than that of the intermediate transmission line 25. The impedance matching device 23, together with the metal disk 21 and the metal back plate 41 (see Appendix), forms the impedance matching device. Figure 4 The impedance formed is approximately equal to the impedance of the intermediate transmission line 25. In a specific embodiment, the metal disk 21 is a disk with a diameter of 0.44 mm; the impedance transformer 23 is 0.168 mm wide and 0.43 mm long; and the line width of the intermediate transmission line 25 is 0.275 mm.

[0034] Several metallized vias 24 are evenly spaced and surround the outer side of the intermediate transmission line 25, the impedance transformer 23, and the metal disk 21; the diameter of each metallized via 24 can be 0.2 mm, and the distance between adjacent metallized vias 24 is preferably chosen to facilitate manufacturing; in this example, the center distance between two adjacent metallized vias 24 is preferably 0.6 mm.

[0035] A pair of threaded holes 22 are located outside the metallized through hole 24 and are symmetrically distributed on opposite sides of the metal disc 21. The pair of threaded holes 22 are through holes and their dimensions are set to match the dimensions of the threaded hole 13 described above.

[0036] The upper metal structure 2 of the coplanar waveguide is formed by coating a good conductor metal layer on the upper surface of the intermediate dielectric structure 3 of the coplanar waveguide. The good conductor metal layer is a metal layer with good conductivity. Preferably, the good conductor metal layer is a gold layer, a copper layer, a platinum layer, etc.

[0037] like Figure 4 The coplanar waveguide intermediate layer dielectric structure 3 is a rectangular dielectric substrate 30, on which a pair of threaded holes 31 and several metallized through holes 32 are provided. The dielectric substrate 30 can be a Panasonic or Rogers dielectric substrate with a thickness of 99 μm. The dielectric constant of the dielectric substrate 30 can be selected from 3.1 to 3.6.

[0038] A pair of threaded holes 31 are located outside the metallized through hole 32, and the pair of threaded holes 31 are also through holes. The dimensions of the pair of threaded holes 31 are set to match the dimensions of the pair of threaded holes 22.

[0039] like Figure 5The coplanar waveguide lower metal structure 4 includes a lower ground layer 40, a metal back plate 41, a pair of threaded holes 42, and several metallized vias 44 located on the lower ground layer 40. There is a gap between the metal back plate 41 and the lower ground layer 40. The metal back plate 41 is located directly below the metal disk 21.

[0040] The metal back plate 41 is preferably annular, but it can also be triangular, quadrilateral, etc. The larger circle diameter of the annular metal back plate 41 can be 0.2-0.6 mm, and the smaller circle diameter can be 0.1-0.3 mm. In a specific embodiment, the larger circle diameter of the annular metal back plate 41 is 0.4 mm, and the smaller circle diameter is 0.2 mm. The diameter of the metal disk 21 is preferably larger than the larger circle diameter of the annular metal back plate 41.

[0041] A pair of threaded holes 42 are located outside the metallized through hole 44, and the pair of threaded holes 42 are also through holes. The dimensions of the pair of threaded holes 42 are set to match the dimensions of the pair of threaded holes 31.

[0042] The aforementioned metallized vias 24, second metallized vias 32, and metallized vias 44 are connected to each other. These metallized vias connect the upper grounding layer 20 in the upper metal structure of the grounded coplanar waveguide and the lower grounding layer 40 in the lower metal structure of the grounded coplanar waveguide, and together they form the signal ground in the grounded coplanar waveguide.

[0043] In this embodiment, a pair of threaded holes 13, a pair of threaded holes 22, a pair of threaded holes 31, and a pair of threaded holes 4 are aligned vertically. The connector and the PCB coplanar waveguide can be assembled into a single unit using a pair of screws (not shown in the figure) inserted into these threaded holes, allowing the metal probe 12 to be electrically connected to the metal disk 21 in a contact manner. In this example, the four-layer structure is fixed together by screws, eliminating the influence of uncontrollable factors such as welding.

[0044] In other embodiments, the threaded holes may be replaced by other types of connecting holes; the connecting parts that replace a pair of screws may also be other types of fasteners, with the selection criteria being the ability to fix the above four-layer mechanism together.

[0045] In the embodiments of this application, the transition structure consists of four parts. The radio frequency signal enters through the port of the solderless connector structure 1, passes through the metal probe 12 in the connector structure 1, and is transmitted to the coplanar waveguide structure. During transmission in the coplanar waveguide structure, impedance discontinuities occur at discontinuities, namely the connection between the metal probe 12 and the metal disk 21, and the connection between the metal disk 21 and the impedance transformer 23, causing the signal to be reflected back to the input port. The structure of this application effectively solves the problem of reduced transmission efficiency caused by these impedance discontinuities.

[0046] First, the impedance discontinuity between the metal disk 21 in the upper coplanar waveguide metal structure 2 and the metal probe 12 in the solderless connector structure 1 is compensated by the metal back disk 41 in the lower coplanar waveguide metal structure 4. This provides impedance compensation for the transition section between the connector's metal probes and the coplanar waveguide connection surface, significantly improving transmission performance. Second, the impedance transformer 23 adjusts the matching performance between the metal disk 21 and the intermediate transmission line 25, thus improving the impedance discontinuity in the transition section between the coplanar waveguide connection surface and the coplanar waveguide transmission line, further enhancing the structure's transmission performance. Therefore, the metal back disk and impedance transformer of this application jointly improve the impedance discontinuity between the solderless connector and the coplanar waveguide, resulting in excellent transmission characteristics for the transition structure between the solderless connector and the PCB coplanar waveguide. The characteristic impedance of the transmission line is approximately 50 ohms, and the bandwidth can cover up to 50 GHz.

[0047] The following are specific examples designed based on the technical solution of this application. The dielectric constant of the dielectric substrate used in this design is 3.1-3.6.

[0048] The impedance matching results and insertion loss results under the simulation results of the matching response of the transition structure are shown below. Figure 6 and 7 ,in, Figure 6 S11 in the text represents impedance matching. Figure 7 S21 in the figure represents the insertion loss. As shown in the figure, the -10dB return loss in this case covers the 50GHz frequency band, and the insertion loss within the bandwidth is within -1.5dB. Therefore, it can be seen that the transition structure in this specific case covers high-frequency applications, has low insertion loss, and can meet the application requirements.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A transition structure for a solderless connector and a coplanar waveguide on a PCB, comprising, from top to bottom, a top-layer connector structure (1), a coplanar waveguide upper metal structure (2), a coplanar waveguide intermediate dielectric structure (3), and a coplanar waveguide lower metal structure (4); wherein, The coplanar waveguide upper metal structure (2) includes an upper ground layer (20), a metal disk (21), an impedance transformer (23), a plurality of first metallized vias (24) located on the upper ground layer (20), and an intermediate transmission line (25). The intermediate transmission line (25) is electrically connected to one end of the impedance transformer (23), and the other end of the impedance transformer (23) is electrically connected to the metal disk (21). The coplanar waveguide intermediate layer dielectric structure (3) includes a dielectric substrate (30) and a plurality of second metallized vias (32) disposed on the dielectric substrate (30); characterized in that, The coplanar waveguide lower metal structure (4) includes a lower ground layer (40), a metal back disk (41), and a plurality of third metallized vias (44) located on the lower ground layer (40). There is a gap between the metal back disk and the lower ground layer to form electrical isolation. The metal back disk (41) is located directly below the metal disk (21). The top-level connector structure (1) includes a base (10), a medium channel (11), and a metal probe (12). The medium channel (11) is located on the lower surface of the base (10) and faces the intermediate transmission line (25). The metal probe (12) is electrically connected to the metal disk (21) in an abutting manner. The plurality of first metallized vias (24), the plurality of second metallized vias (32), and the plurality of third metallized vias (44) are connected to each other so that the upper ground layer (20) and the lower ground layer (40) are connected together and together form the signal ground in the coplanar waveguide; At least one threaded hole is provided at corresponding positions on the base (10), upper grounding layer (20), dielectric substrate (30) and lower grounding layer (40), and the four are connected by threaded fasteners.

2. The transition structure for a solderless connector and a coplanar waveguide on a PCB according to claim 1, characterized in that, The metal probe (12) penetrates the base (10) in the vertical direction and is in perpendicular contact with the metal disk (21).

3. The transition structure for a solderless connector and a coplanar waveguide on a PCB according to claim 1, characterized in that, The coplanar waveguide transmission structure consisting of the intermediate transmission line (25), the upper ground layer (20), the dielectric substrate (30), and the lower ground layer (40) has an impedance of 50 ohms.

4. The transition structure for a solderless connector and a coplanar waveguide on a PCB according to claim 1, characterized in that, The metal disk is a disc, and the metal back disk is a ring.

5. The transition structure for a solderless connector and a coplanar waveguide on a PCB according to claim 4, characterized in that, The diameter of the disk is larger than the diameter of the great circle of the ring.

6. The transition structure for a solderless connector and a coplanar waveguide on a PCB according to claim 4, characterized in that, The diameter of the metal disk (21) is 0.2-0.7 mm, and the large circle diameter of the metal back disk (41) is 0.2-0.6 mm and the small circle diameter is 0.1-0.3 mm.

7. The transition structure for a solderless connector and a coplanar waveguide on a PCB according to claim 1, characterized in that, The plurality of first metallized vias (24) are evenly spaced and surround the outer side of the intermediate transmission line (25), the impedance transformer (23) and the metal disk (21).

8. The transition structure for a solderless connector and a coplanar waveguide on a PCB according to claim 7, characterized in that, The dielectric constant of the dielectric substrate (30) is selected to be 3.1-3.

6.

9. The transition structure for a solderless connector and a coplanar waveguide on a PCB according to claim 1, characterized in that, The impedance transformer (23) is a metal wire, the width of which is smaller than the width of the intermediate transmission line (25).

Images