JPH10327004A - Circuit module having coaxial connector - Google Patents

Abstract

(57) [Summary] (Modified) [Problem] A K connector has been used for a circuit module used at a high frequency of GHz or more. Processing and time-consuming work of pouring solder through a hole having a diameter of 0.8 mm were required. A ground line is provided on both sides of a signal line on a circuit board at a joint between a microstrip line, which is a signal line of a circuit substrate, and a coaxial connector. By making the distance between the pads smaller than the diameter of the dielectric 4 of the coaxial connector, S
By using a connector such as an MA connector, reflection characteristics equivalent to those of a K connector can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit module having a coaxial connector and a circuit board having a signal line such as a microstrip line or a coplanar line on its surface.

[0002]

2. Description of the Related Art It is necessary to minimize the reflection loss at the joint between a coaxial connector and a signal line on a circuit board. Particularly at high frequencies above GHz, K connectors as shown in the connector catalog of Wiltron have been used. In the K connector, as shown in the connector catalog of Wiltron, the reflection loss can be suppressed to -15 dB or less up to 40 GHz.

[0003]

The conventional method has the following problems.

That is, as shown in the connector catalog of Wiltron, mounting the K connector on the module base requires high-precision processing of the module base and Φ0.8.
A laborious work of pouring solder through a hole of mm was required.

An object of the present invention is to provide a connector and a circuit board which can obtain the same reflection characteristics as a K connector by using a connector whose module base is easier to process and assemble than a K connector such as an SMA connector. To provide a joining structure.

[0006]

According to the present invention, two ground pads are provided on both sides of a signal line on a circuit board at a joint between the signal line of the circuit board and the coaxial connector, and between two pads of the two senders. Is made smaller than the diameter of the dielectric of the coaxial connector, so that a reflection characteristic equivalent to that of the K connector can be obtained using a connector such as an SMA connector.

[0007]

FIG. 1 is a block diagram showing an embodiment of a circuit module according to the present invention.

In FIG. 1, a circuit module is constituted by a coaxial connector to which a coaxial line 7 is connected with a dielectric 4 and a core wire 5 and a ground around an outer periphery of the dielectric 4 which is integrated with or joined to the module base 6. And two ground pads 2 provided on both sides of the microstrip line 1 at the junction between the microstrip line 1 and the connector.
The circuit board 3 has a and b as surface patterns.

The distance 2 between the two ground pads 2a, 2b
c is shorter than the diameter 4a of the dielectric 4 of the coaxial connector.

FIG. 2 shows a waveform when a TDR waveform is applied to the circuit module of the present invention.

A waveform 8 is a waveform when there is no ground pad 2a, 2b in the circuit module of FIG. 1, and a waveform 9 is a waveform when there is the ground pad 2a, 2b according to the present invention.

The electric signal transmitted through the coaxial line 7 spreads the electrolysis at the joint between the coaxial connector and the substrate. Therefore, when the characteristic impedance of the coaxial line 7 and the characteristic impedance of the microstrip line 1 on the substrate are equalized, the characteristic impedance of the joint between the coaxial connector and the substrate becomes higher than the characteristic impedance of the coaxial line 7 and the microstrip line 1. After applying the waveform, the waveform 8 has a coaxial line 7
The reflected wave on the positive side is observed after a time (T1-T0), which is twice the electric length obtained by adding the electric length of the connector and the electric length of the connector.

Since the two ground pads 2a and 2b spread the electric field, the characteristic impedance of the joint between the coaxial connector and the substrate can be made close to the characteristic impedance of the coaxial line 7 or the microstrip line 1. Therefore, the distance 2c between the two pads is defined as the diameter 4a of the dielectric 4 of the coaxial connector> the distance 2c between the two pads.
> By setting an appropriate value in the wiring width of the microstrip line 1, it is possible to reduce the reflected wave as in the waveform 9. In FIG. 1, the dielectric 4 may be air. The circuit board may be a two-layer board having a solid back surface, or a single-layer board having only a surface layer.

FIG. 3 is a block diagram of a circuit module showing another embodiment of the present invention.

Referring to FIG. 3, the circuit module comprises a coaxial connector to which a coaxial line 7 is connected, comprising a dielectric 4 and a core 5 and a ground around the dielectric 4 which is integrated with or joined to the module base 6. And two ground pads 2 provided on both sides of the microstrip line 1 at the junction between the microstrip line 1 and the connector.
The circuit board 3 has a and b as surface patterns. The distance 2c between the two ground pads 2a, 2b is shorter than the diameter 4a of the dielectric 4 of the coaxial connector.

Further, at the joint between the microstrip line 1 and the connector, the line width of the microstrip line 1 is set to a line width 1a smaller than the line width 1b having the same characteristic impedance as the coaxial line 7.

According to this embodiment, the spread of the electric field can be further suppressed as compared with the configuration diagram of the module shown in FIG. 1, so that the characteristic impedance of the joint between the coaxial connector and the substrate can be made smaller than that of the module configuration shown in FIG. Also coaxial line 7
In addition, it becomes possible to approach the characteristic impedance of the microstrip line 1.

FIG. 4 is a block diagram of a circuit module showing another embodiment of the present invention, and FIG.
It is sectional drawing in A '.

In FIG. 4, the circuit module comprises a coaxial connector to which a coaxial line 7 is connected, which is constituted by a dielectric 4 and a core 5 and a ground on the outer periphery of the dielectric 4 which is integrated with or joined to the module base 6. And two ground pads 2 provided on both sides of the microstrip line 1 at the junction between the microstrip line 1 and the connector.
a, 2b as surface layer patterns, and furthermore, as shown in FIG.
Are connected by conductors 12 by plating or the like on the end surface of the circuit board.

The distance 2 between the two ground pads 2a, 2b
c is shorter than the diameter 4a of the dielectric 4 of the coaxial connector. Further, the two ground pads 2a and 2b are electrically connected to the module base 6 by solder.

According to this embodiment, the impedance between the ground 6 of the connector and the ground 11 of the microstrip line can be reduced, so that the reflection characteristics equivalent to those of the circuit module of FIG. Becomes possible.

In FIGS. 4 and 5, the multi-layer substrate is a three-layer substrate, but a multi-layer substrate having three or more layers may be used. In FIG. 5, two ground pads 2a, 2b
The conductor 11 of the second layer and the conductor 13 of the lowermost layer are connected by the conductor 12 by plating, but only the two ground pads 2a and 2b and the conductor 11 of the second layer are connected by the conductor 12 by plating. You may. In FIG. 5, the two ground pads 2a and 2b are electrically connected to the module base 6 by solder 14, but may be connected by using an L-shaped conductor instead of solder.

FIG. 6 is a configuration diagram of a circuit module showing another embodiment of the present invention.

In FIG. 6, the circuit module comprises a coaxial connector to which a coaxial line 7 is connected, wherein the coaxial line 7 is connected to the dielectric 4 and the core 5 and the module base 6 and is formed of a ground on the outer periphery of the dielectric 4. And a circuit board 16 having a coplanar line 15. The distance 17c between the grounds 17a and 17b of the coplanar line is shorter than the diameter 4a of the dielectric 4 of the coaxial connector. Further, at the joint between the coplanar line 15 and the connector, the line width of the coplanar line 15 is set to a line width 1a smaller than the line width 1b having the same characteristic impedance as the coaxial line 7.

The electric signal transmitted through the coaxial line 7 spreads an electric field at the joint between the coaxial connector and the substrate. According to the present embodiment, since the spread of the electric field can be suppressed as compared with the case where the line width of the coplanar line 15 is fixed, the characteristic impedance of the joint between the coaxial connector and the substrate is reduced.
The characteristic impedance of the coaxial line 7 and the coplanar line 15 can be made closer to that of the case where the line width of the coplanar line 15 is fixed.

FIG. 7 is a block diagram of a circuit module showing another embodiment of the present invention, and FIG.
It is sectional drawing in B '.

In FIG. 7, the circuit module comprises a coaxial connector to which a coaxial line 7 is connected, which is constituted by a ground on the outer periphery of the dielectric 4 integrated with or bonded to the dielectric 4, the core wire 5 and the module base 6. And a coplanar line 15 as a surface layer pattern, and grounds 17a, 17b on both sides of the coplanar line and the conductor 11 of the second layer are connected by a conductor 12 by plating or the like on the end face of the circuit board as shown in FIG. It is composed of a multilayer circuit board 18 having more than one layer.

The coplanar line 15 includes a ground 17a,
The distance 17c of 17b is set to the diameter 4 of the dielectric 4 of the coaxial connector.
a, and the line width of the coplanar line 15 at the joint between the coplanar line 15 and the connector is set to a line width 1a smaller than the line width 1b having the same characteristic impedance as the coaxial line 7. Further, the grounds 17 a and 17 b of the coplanar line 15 are electrically connected to the module base 6 by the solder 14.

According to this embodiment, the impedance between the ground 6 of the connector and the grounds 17a and 17b of the coplanar line 15 can be reduced, so that the reflection characteristics equivalent to those of the circuit module of FIG. It is possible to do.

In FIGS. 7 and 8, the multi-layer substrate is a three-layer substrate, but a multi-layer substrate of three or more layers may be used.

In FIG. 8, the grounds 17a and 17b of the coplanar line 15 are connected to the conductor 11 of the second layer and the conductor 13 of the lowermost layer by the conductor 12 formed by plating or the like. And 2
Only the conductor 11 of the layer may be connected by the conductor 12 by plating or the like.

In FIG. 8, the grounds 17a and 17b of the coplanar line 15 are electrically connected to the module base 6 by the solder 14, but may be connected by using an L-shaped conductor instead of the solder.

[0033]

As described above, according to the present invention, the SM
By using a connector whose module base is easier to process and assemble than a K connector such as an A connector, it is possible to obtain reflection characteristics equivalent to those of the K connector, thereby realizing cost reduction of the module.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of a circuit module.

FIG. 2 is a waveform diagram when a TDR waveform is applied to a circuit module.

FIG. 3 is a configuration diagram showing another embodiment of the circuit module.

FIG. 4 is a configuration diagram showing another embodiment of a circuit module.

FIG. 5 is a sectional view taken along line AA ′ of the circuit module shown in FIG. 4;

FIG. 6 is a configuration diagram showing another embodiment of the circuit module.

FIG. 7 is a configuration diagram showing another embodiment of the circuit module.

8 is a cross-sectional view taken along line BB 'of the circuit module shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Microstrip line, 2 ... Ground pad, 3 ... Circuit board, 4 ... Dielectric, 5 ... Core wire, 6 ... Module base, 7 ... Coaxial line, 8 ... TDR waveform without ground pad, 9 ... Ground TDR waveform when there is a pad, 10: multilayer circuit board, 11: second layer conductor of multilayer circuit board, 12: conductor connecting between layers of multilayer circuit board by plating or the like at end face, 13: final layer of multilayer circuit board Lower layer conductor, 14: ground pads 2a, 2b and module base 6
15 ... coplanar line, 16 ... circuit board, 17 ... ground of coplanar line, 18 ... multilayer board.

Claims (5)

[Claims] 1. A circuit board having a signal line formed of a microstrip line on a surface layer of a substrate and a circuit module having a coaxial connector for connecting the signal line and a coaxial line. A circuit module, wherein two ground pads are provided on both sides of a signal line on a substrate at a connection portion between the two and a distance between the two ground pads is shorter than a diameter of a dielectric of the coaxial connector. 2. The circuit module according to claim 1, wherein a signal line on the substrate at a portion connected to the coaxial connector provided with the ground pad is thinner than a signal line on the substrate at a portion without the ground pad. A circuit module characterized in that: 3. The circuit module according to claim 1, wherein a circuit board having three or more layers is used, and a ground of a second layer and a pad of a ground of the surface are connected at an end face of the substrate, and a ground pad of the surface is formed. And a ground of a coaxial connector. 4. A circuit board having a signal line composed of a coplanar line on a surface layer of a substrate, and a circuit module having a coaxial connector for connecting the signal line and the coaxial line. A circuit module, characterized in that a signal line on a substrate at a connection portion is thinner than a signal line on a substrate at another portion. 5. The circuit module according to claim 4, wherein a circuit board having three or more layers is used, the ground of the second layer and the ground of the surface layer are connected at an end face of the substrate, and the ground of the surface layer and the coaxial connector are connected. A circuit module having a direct electrical connection to a ground.