JP2010108691A - Connection structure and connecting method of coax connector in multi-layer printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve matching of impedances without mounting components with inductivity, in connection of a coax connector with a multi-layer printed wiring board in which a connection in a micro-strip line connected with the coax connector is formed capacitively. <P>SOLUTION: In the connection structure of the coax connector in a multi-layer printed wiring board in which a connection in the micro-strip line arranged in a case and connected with a center conductor of the coax connector is formed capacitively, a notched part is provided at a side of the multi-layer printed wiring board opposed to a side of the case into which the coax connector in the vicinity of the connection in the micro-strip line is inserted. By setting a length of a part of the center conductor located on the notched part not connected with the connection in the micro-strip line at a length most appropriate to a desired frequency, a desired inductivity is to be given to the part located on the notched part in the center conductor. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a connection structure and a connection method of coaxial connectors in a multilayer printed circuit board, and more particularly, connection of coaxial connectors in a multilayer printed circuit board for connecting a multilayer printed circuit board on which a microstrip line is formed and the coaxial connector. The present invention relates to a structure and a connection method.

  Conventionally, a printed circuit board, which is a planar transmission circuit, has been used as a high-frequency transmission circuit, and such a printed circuit board in which a microstrip line is formed as a transmission line is known.

  As a printed board for forming such a microstrip line, a microstrip line can be easily formed by providing a ground plane in a layer adjacent to a wiring layer on which a wiring pattern is formed. A multilayer printed circuit board is used.

  The multilayer printed circuit board on which the microstrip line is formed is mounted on a device, and the multilayer printed circuit board mounted on the device is connected to a coaxial cable or the like via a coaxial connector.

Here, the connection structure of the coaxial connector in the conventional multilayer printed circuit board will be described in detail with reference to FIGS.

  FIG. 1 (a) shows a schematic configuration perspective view showing a main part of a multilayer printed circuit board provided with a microstrip line in a housing, and FIG. 1 (b) shows a schematic configuration perspective view. FIG. 1 is a schematic cross-sectional explanatory view showing a main part when a coaxial connector is connected to the multilayer printed board shown in FIG.

  In FIG. 1A, the outer side surface portion 22b of the housing 22 is omitted in order to facilitate understanding of the connection structure of the coaxial connector in the multilayer printed board.

In the multilayer printed board 100 shown in FIGS. 1A and 1B, dielectrics 12a, 12b, and 12c having a predetermined thickness are laminated to form first to fourth layers.

  A microstrip line 14 is formed on the first layer located on the upper surface of the dielectric 12a.

  In addition, the second layer located between the lower surface of the dielectric 12a and the upper surface of the dielectric 12b has an inner layer 16 on which a ground pattern is formed, and the lower surface of the dielectric 12b. An inner layer 18 having a predetermined pattern is formed on the third layer located between the upper surface of the dielectric 12c.

  Furthermore, a ground surface 20 is formed on the fourth layer located between the lower surface side surface of the dielectric 12 c and the bottom surface 22 a of the housing 22.

  Such a multilayer printed circuit board 100 is fixedly disposed on the bottom surface 22a of the housing 22 by screws (not shown) or the like, and is coaxially inserted through a hole 24 provided in the outer surface portion 22b of the housing 22. The central conductor 28 of the connector 26 and the connecting portion 14a in the microstrip line 14 formed in the first layer are connected by solder.

  The characteristic impedance of the coaxial line 30 of the coaxial connector 26 inserted into the hole 24 is equal to the characteristic impedance of the line portion 14b in the microstrip line 14, and the characteristic impedance is, for example, 50Ω.

Here, since the connection portion 14a in the microstrip line 14 provided in the first layer of the multilayer printed circuit board 100 is connected to the center conductor 28 of the coaxial connector 26 by solder, the periphery of the solder is improved and the center In order to increase the connection strength between the conductor 28 and the multilayer printed circuit board 100, the microstrip line 14 is formed to have a width L2 wider than the pattern width L1 of the line portion 14b.

  The characteristic impedance of the line portion 14b in the microstrip line 14 is equal to the characteristic impedance of the coaxial line 30 of the coaxial connector 26 as described above, and is, for example, 50Ω.

By the way, the connection part 14a in the microstrip line 14 is formed to have a width L2 wider than the pattern width L1 of the line part 14b in the microstrip line 14 having a characteristic impedance of 50Ω. .

  When the multilayer printed circuit board 100 and the coaxial connector 26 are connected, the characteristic impedances match (for example, match at 50Ω), and the coaxial line 30 of the coaxial connector 26 and the line portion 14b of the microstrip line 14 Are connected via the connecting portion 14a of the microstrip line 14 having capacitance, impedance matching is not achieved, signal reflection occurs, and electrical performance (for example, VSWR, transmission loss, etc.). It has become a problem to cause deterioration.

As a means for solving such a problem, as shown in the multilayer printed circuit board 200 in FIGS. 2A and 2B, the connection portion 14 a in the microstrip line 14 is located near the connection portion 14 a in the microstrip line 14. There is known a method of preventing the occurrence of signal reflection by matching the impedance by mounting an inductive component 32 such as a chip inductor that cancels the capacitance.

However, since the inductive component 32 is mounted on the multilayer printed circuit board 200, the number of components increases, resulting in an increase in product cost and an obstacle to miniaturization of the product itself. Has arisen as a new problem.

  Furthermore, due to the performance variation of the inductive component 32, even if the multilayer printed circuit board 200 is mounted with the inductive component 32, there may be a case where sufficient impedance matching cannot be achieved, In the multilayer printed circuit board 200 after mounting the component 32, individual adjustments such as changing the constant of the component 32 and changing the mounting position are necessary, and there is a problem that the number of work steps increases in the production process.

Note that the prior art that the applicant of the present application knows at the time of filing a patent is not an invention related to a known literature invention, and therefore there is no prior art document information to be described.

  The present invention has been made in view of the various problems of the prior art as described above, and the object of the present invention is to form a connection portion in the microstrip line connected to the coaxial connector with a capacity. Provided is a coaxial connector connection structure and connection method in a multilayer printed circuit board that enables impedance matching without mounting inductive components in the connection between the multilayer printed circuit board and the coaxial connector. It is what.

  In order to achieve the above object, the present invention provides a multi-layer printed circuit board used as a planar transmission line having a notch in the vicinity of a connection portion of a microstrip line connected to a coaxial connector, and coaxially passes through the notch. The center conductor of the connector is connected to the connection portion of the microstrip line so that the center conductor of the coaxial connector located on the notch has an inductivity that cancels the capacitance of the connection portion of the microstrip line. It is a thing.

Therefore, according to the present invention, impedance matching can be achieved without mounting an inductive component in the vicinity of the microstrip line.

  For this reason, according to the present invention, it is possible to prevent an increase in product cost and to reduce the size of the product itself.

  Further, according to the present invention, it is not necessary to individually adjust the multilayer printed circuit board, and impedance matching can be achieved without increasing the number of production steps.

That is, the invention according to claim 1 of the present invention is the connection of the coaxial connector in the multilayer printed board in which the connection portion in the microstrip line connected to the central conductor of the coaxial connector is formed with a capacity. In the structure, a notch portion is provided in a side surface portion of the multilayer printed board facing the side surface portion of the housing into which the coaxial connector in the vicinity of the connection portion in the microstrip line is inserted, and the connection in the microstrip line By setting the length of the part located on the notch in the center conductor not connected to the part to the optimum length for the desired frequency, the position on the notch in the center conductor is set. The desired portion is made to have a desired inductivity.

  Therefore, according to the first aspect of the present invention, the capacitance matching of the connecting portion in the microstrip line is canceled by the inductivity given to the portion located on the notch portion in the center conductor, thereby matching the impedance. It can be taken.

  According to a second aspect of the present invention, in the first aspect of the present invention, a stub connection pattern is provided around the connection portion of the microstrip line.

  Therefore, according to the second aspect of the present invention, the electrical performance is deteriorated due to a deviation from the design value such as the thickness of the dielectric, the dielectric constant of the dielectric, and the pattern width of the microstrip line generated during the production of the multilayer printed board By connecting the connection part of the microstrip line and the stub correspondingly, it becomes possible to adjust the capacitance of the connection part in the microstrip line, improving the electrical performance in the multilayer printed circuit board and matching the impedance. Can take.

  According to a third aspect of the present invention, the connection of the coaxial connector in the multilayer printed board in which the connection portion in the microstrip line connected to the central conductor of the coaxial connector is formed with capacitance is arranged in the housing. In the method, the center conductor of the coaxial connector is made inductive to cancel out the capacitance of the connecting portion.

  Therefore, according to the third aspect of the present invention, it is possible to prevent signal reflection from occurring at the connection portion in the microstrip line.

  Since the present invention is configured as described above, the microstrip line connected to the coaxial connector has inductivity in the connection between the coaxial printed circuit board and the multilayer printed circuit board in which the connection portion is formed with capacitance. There is an excellent effect that impedance matching can be achieved without mounting components.

  Hereinafter, an example of an embodiment of a coaxial connector connection structure in a multilayer printed circuit board according to the present invention will be described in detail with reference to the accompanying drawings.

  In the following description, the same or equivalent configuration as the coaxial connector connection structure in the multilayer printed circuit board according to the prior art described with reference to FIGS. Detailed description of the configuration and operation will be omitted as appropriate.

Here, FIG. 3A is a schematic configuration perspective view showing the main part of the multilayer printed circuit board used in the connection structure of the coaxial connector in the multilayer printed circuit board according to the present invention, and FIG. FIG. 3B is a schematic cross-sectional explanatory view showing the main part when the coaxial connector is connected to the multilayer printed circuit board shown in FIG. 3A, and FIG. A view of arrow A in 3 (b) is shown.

  In order to facilitate understanding of the present invention, the outer surface portion 22b of the housing 22 is omitted in FIG. 3A, and a part of the outer surface portion 22b of the housing 22 is shown in FIG. 3C. Is omitted.

This multilayer printed circuit board 10 is formed by laminating dielectrics 12a, 12b, and 12c made of an insulating resin having a predetermined thickness in the same manner as the multilayer printed circuit board 100 described above, thereby forming the first to fourth layers. The microstrip line 14 is formed in the first layer, the inner layer 16 in which the ground pattern is formed is formed in the second layer, and a predetermined pattern is formed in the third layer. An inner layer 18 is formed, and a ground plane 20 is formed in the fourth layer. However, in the vicinity of the connection portion 14a in the microstrip line 14 connected to the coaxial connector 26, the dielectric layer 12a to the fourth layer are formed. This is different from the multilayer printed circuit board 100 in that the notch 34 is formed up to the ground plane 20.

  The notch 34 is provided on the side surface 10a of the multilayer printed circuit board 10 facing the outer surface 22b of the housing 22 into which the coaxial connector 26 is inserted. The width L3 and the depth L4 of the notch 34 have desired frequencies. The optimum value is set by calculation using values such as the relative dielectric constant of the dielectric 12a, the dielectric thickness L5, the pattern width L2 of the connecting portion 14a, the pattern length L8, and the substrate thickness L6 of the substrate 10. At this time, it is effective to use an optimization function of the simulator.

  The multilayer printed circuit board 10 is fixed to the bottom surface 22 a of the housing 22 with screws or the like, and the end portion of the central conductor 28 of the coaxial connector 26 inserted into the hole 24 provided in the outer surface portion 22 b of the housing 22. 28a and the connecting portion 14a in the microstrip line 14 formed in the first layer are connected by solder.

  The characteristic impedance of the coaxial line 30 in the coaxial connector 26 inserted into the hole 24 is equal to the characteristic impedance of the line portion 14b in the microstrip line 14, and the characteristic impedance is, for example, 50Ω.

Here, since the connection portion 14a in the microstrip line 14 provided in the first layer of the multilayer printed circuit board 10 is connected to the end portion 28a of the central conductor 28 of the coaxial connector 26 by solder, the solder periphery is improved. In order to increase the connection strength between the central conductor 28 and the multilayer printed board 10, the microstrip line 14 is formed to have a pattern width L2 wider than the pattern width L1 of the line portion 14b. The characteristic impedance of the line portion 14b in the microstrip line 14 is equal to the characteristic impedance of the coaxial line 30 of the coaxial connector 26 as described above, and is, for example, 50Ω.

  The characteristic impedances of the coaxial line 30 of the coaxial connector 26 and the line part 14b of the microstrip line 14 are identical (for example, 50Ω), but when the multilayer printed circuit board 10 and the coaxial connector 26 are connected. In other words, the coaxial line 30 in the coaxial connector 26 and the line part 14b in the microstrip line 14 are connected via the connection part 14a in the microstrip line 14 having capacitance.

  In this case, impedance matching is achieved by setting the length L7 of the portion 28b located on the notch 34 in the center conductor 28 to an optimum length for the desired frequency.

  That is, in the connection structure of the coaxial connector in the multilayer printed board according to the present invention, the capacity per unit length of the parallel line or the microstrip line is inversely proportional to the distance between the two wires (distance between the strip and the grant surface). It utilizes that the inductivity per unit length of the parallel line or the microstrip line is proportional to the distance between the two wires.

  That is, for example, the reference ground plane for the line portion 14b in the microstrip line 14 having a characteristic impedance of 50Ω or the connection portion 14a in the microstrip line 14 having capacitance is the inner layer 16, whereas the coaxial connector 26 is used. The reference ground plane of the portion 28b located on the notch 34 in the central conductor 28 is the bottom surface 22a of the housing 22 because the notch 34 is provided in the multilayer printed circuit board 10.

  Therefore, the notch 34 in the central conductor 28 of the coaxial connector 26 of the board 10 of the board 10 is larger than the distance L5 from the connecting part 14a in the microstrip line 14 having a dielectric thickness to the inner layer 16 as the reference ground plane of the line 14b. By increasing the distance L6 to the bottom surface 22a of the housing 22 that is the reference ground plane of the portion 28b positioned above, the portion 28b positioned on the notch 34 in the center conductor 28 can have inductivity. It is.

  Then, by setting the length L7 of the portion 28b located on the notch 34 in the center conductor 28 to an optimum length for the desired frequency, the portion 28b located on the notch 34 in the center conductor 28. The inductivity of the connection portion 14a in the microstrip line 14 is offset by the inductivity of the portion 28b located on the cutout portion 34 in the set center conductor 28, and the impedance is set. To be consistent.

  Further, as in the multilayer printed board 50 shown in FIG. 4, by providing a pattern for stub connection around the connection portion 14a in the microstrip line 14, the thickness of the multilayer printed board 50 and the dielectric material are produced at the production stage. Even if the thickness, the dielectric constant of the dielectric, the pattern in the microstrip line 14 deviate from the design value, and the electrical performance of the multilayer printed circuit board 50 deteriorates, the microstrip line can be connected by connecting the stub. The electrical performance of the multi-layer printed circuit board 50 may be improved by adjusting the capacitance of the connecting portion 14a.

As described above, according to the present invention, in the side surface 10a facing the outer side surface portion 22b of the housing 22 into which the coaxial connector 26 in the vicinity of the connection portion 14a in the microstrip line 14 formed on the multilayer printed board 10 is inserted. By providing the notch 34, the portion 28 b located on the notch 34 that is not connected to the microstrip line 14 in the center conductor 28 of the coaxial connector 26 has inductivity, and the notch in the center conductor 28 that has inductivity is provided. Since the capacities of the connecting portions 14a in the microstrip line 14 are offset by the portion 28b located on the notch portion 34, an inductive component such as a chip inductance is not mounted in the vicinity of the microstrip line 14. Impedance can be matched Than is.

  Therefore, according to the present invention, it is not necessary to mount an inductive component, so that an increase in product cost can be suppressed and the product itself can be downsized.

  Further, according to the present invention, since there is no need to mount an inductive component, there is no process for correcting the performance variation of the component in the production process, and impedance matching is performed without increasing the number of production processes. Can be taken.

  In the above-described embodiment, the case where the characteristic impedances of the line portion 14b in the microstrip line 14 and the coaxial line 30 in the coaxial connector 26 are both 50Ω has been described. However, the present invention is not limited to this. Of course, as long as the characteristic impedances of the line portion 14b in the microstrip line 14 and the coaxial line 30 in the coaxial connector 26 are equal, one having an arbitrary impedance may be used.

  The present invention can be used for connection between a multilayer printed board on which a high-frequency circuit is formed and a coaxial connector.

FIG. 1A is a schematic perspective view illustrating a main part of a multilayer printed circuit board disposed in a housing and having a microstrip line, and FIG. 1B is a perspective view of FIG. It is a schematic structure cross-sectional explanatory drawing which shows the principal part when a coaxial connector is connected to the multilayer printed circuit board shown in FIG. FIG. 2A is a schematic perspective view illustrating a main part of a multilayer printed board on which a conventional microstrip line is formed, and FIG. 2B illustrates the multilayer shown in FIG. It is schematic structure cross-sectional explanatory drawing which shows the principal part when a coaxial connector is connected to the printed circuit board. FIG. 3A is a schematic perspective view illustrating the main part of the multilayer printed circuit board used in the coaxial connector connection structure in the multilayer printed circuit board according to the present invention, and FIG. FIG. 3C is a schematic cross-sectional explanatory view showing a main part when a coaxial connector is connected to the multilayer printed board shown in a), and FIG. 3C is a view as seen from an arrow A in FIG. FIG. 4 is a schematic configuration explanatory view showing a modification of the connection structure of the coaxial connector in the multilayer printed board according to the present invention.

Explanation of symbols

10, 50, 100, 200 Multilayer printed circuit board 12a, 12b, 12c Dielectric 14 Microstrip line 16, 18 Inner layer 20 Ground plane 22 Housing 24 Hole 26 Coaxial connector 28 Central conductor 30 Coaxial line 32 Parts 34 Notch

Claims (3)

In the connection structure of the coaxial connector in the multilayer printed board in which the connection portion in the microstrip line connected to the central conductor of the coaxial connector is formed with capacitance in the housing,
In the microstrip line, a cutout portion is provided in a side surface portion of the multilayer printed board facing the side surface portion of the housing into which the coaxial connector in the vicinity of the connection portion is inserted,
By setting the length of the portion located on the notch in the center conductor not connected to the connection portion in the microstrip line to an optimum length for a desired frequency, A connection structure for a coaxial connector in a multilayer printed circuit board, wherein a desired inductivity is given to a portion located on the notch. In the connection structure of the coaxial connector in the multilayer printed circuit board according to claim 1,
A connection structure for a coaxial connector in a multilayer printed board, wherein a stub connection pattern is provided around a connection portion of the microstrip line. In the connection method of the coaxial connector in the multilayer printed circuit board, in which the connection portion in the microstrip line that is arranged in the housing and is connected to the central conductor of the coaxial connector is formed with a capacity,
A method for connecting coaxial connectors in a multilayer printed board, wherein the capacitive property of the connecting portion is offset by imparting inductivity to the central conductor of the coaxial connector.

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