JP2002148291A - Measuring instrument for characteristic impedance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a characteristic impedance measuring instrument which can efficiently take a measurement, while surely performing electrostatic discharging. SOLUTION: This characteristic impedance measuring instrument 1 has a TDR meter 2, which sends an electric signal to a printed wiring board 5 and receives the signal to measures characteristic impedance and also displays the measurement result and a probe 4, which is electrically connected to the TDR meter 2 via a cable 3. The probe 4 has signal pins 41, which are made to abut against signal measurement pad 51 of the printed wiring board 5 and a ground pin 42, which is made to abut against a grounding measurement pad 52. The ground pin 42 is connected to a ground line 32 of a cable 3. The signal pin 41 has a switching means 43 for switching between connections with the signal line 31 and a ground line 32 of the cable 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a characteristic impedance measuring instrument for measuring the characteristic impedance of a printed wiring board.

[0002]

2. Description of the Related Art Conventionally, a characteristic impedance measuring machine 9 as shown in FIG. 5 has been used to measure the characteristic impedance of a printed wiring board. The characteristic impedance measuring instrument 9 has a TDR meter 92 and a probe 94 electrically connected to the TDR meter 92.

The TDR meter 92 transmits and receives an electric signal to and from the printed wiring board 5, measures the characteristic impedance, and displays the measurement result. The probe 94 has a signal pin 941 and a ground pin 942. The probe 94 is connected to the TDR meter 92.
Are connected by a cable 93.

When the characteristic impedance of the printed wiring board 5 is measured by the characteristic impedance measuring device 9, the signal pins 941 and the ground pins 942 of the probe 94 are connected to the signal pins provided on the printed wiring board 5. By contacting the measuring pad 51 and the grounding measuring pad 52,
The electric signal is transmitted and received between the printed wiring board 5 and the TDR meter 92.

[0005]

However, the conventional characteristic impedance measuring instrument 9 has the following problems. That is, the signal measurement pad 51 may be charged with static electricity. With the signal measurement pad 51 charged,
When the signal pin 941 of the characteristic impedance measuring machine 9 is brought into contact with the signal measuring pad 51 to perform measurement, the charged static electricity is transferred to the signal pin 941 through the T pin.
It flows into the DR meter 92.

On the other hand, since the TDR meter 92 has low withstand voltage, there is a possibility that a problem may occur due to the inflow of the static electricity. Therefore, it is necessary to gradually charge the signal measuring pad 51 using a conductive brush or the like for each measurement. For this reason, there is a problem that the measurement efficiency is low and that it is not always possible to reliably perform the charging.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a characteristic impedance measuring instrument capable of efficiently measuring a voltage while reliably reducing a charge.

[0008]

According to a first aspect of the present invention, there is provided a TDR meter which transmits and receives an electric signal to a printed wiring board, measures a characteristic impedance, and displays a measurement result;
In a characteristic impedance measuring instrument having a probe electrically connected to the TDR meter via a cable, the probe is brought into contact with a signal measurement pad electrically connected to a signal layer on the printed wiring board. A signal pin; and a ground pin for contacting a grounding measurement pad electrically connected to a ground layer of the printed wiring board, wherein the ground pin is connected to a ground terminal of the TDR meter. Connected to the wire
The signal pin has a switching means for switching between connection to a signal line of the cable connected to a signal terminal of the TDR meter and connection to the ground line. is there.

Most notably, in the present invention, the signal pin has switching means for switching between connection with the signal line and connection with the ground line. As the switching means, for example, a relay switch can be used.

Next, the operation and effect of the present invention will be described.
In measuring the characteristic impedance of the printed wiring board using the characteristic impedance measuring instrument, the signal pin of the probe is brought into contact with the signal measurement pad of the printed wiring board, and the ground pin is connected to the ground of the printed wiring board. Contact with the measuring pad. At this time, the signal pin is connected to the ground line. As a result, the static electricity charged on the signal measurement pad is gradually reduced via the signal pin and the ground line.

Then, the signal pins are connected to the signal lines by the switching means, and electric signals are transmitted and received between the TDR meter and the printed wiring board via the signal pins.

As described above, since the characteristic impedance measuring apparatus of the present invention has the switching means, the signal pin can be connected to the ground line before the measurement is performed. Thereby, before the measurement of the characteristic impedance, the static electricity charged on the signal measuring pad can be reliably discharged through the signal pin and the ground line. Also,
When measuring the characteristic impedance, the measurement can be easily started by switching the connection of the signal pin to the signal line by the switching means. Therefore, the characteristic impedance can be measured efficiently.

As described above, according to the present invention, it is possible to provide a characteristic impedance measuring instrument capable of performing an efficient measurement while reliably performing charging.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment A characteristic impedance measuring instrument according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, a characteristic impedance measuring instrument 1 of the present embodiment transmits and receives an electric signal to and from a printed wiring board 5, measures a characteristic impedance, and displays a measurement result.
And a probe 4 electrically connected to the TDR meter 2 via a cable 3.

As shown in FIG. 2, the probe 2 has a signal pin 41 to be brought into contact with a signal measuring pad 51 electrically connected to a signal layer 53 of the printed wiring board 5.
And a ground pin 42 that comes into contact with a ground measurement pad 52 that is electrically connected to a ground layer 54 of the printed wiring board 5.

The cable 3 has a ground line 32 connected to a ground terminal of the TDR meter 2 and a signal line 31 connected to a signal terminal of the TDR meter 2. The ground pin 42 is connected to the ground line 32 of the cable 3. On the other hand, as shown in FIGS. 2 and 3, the signal pin 41 has switching means 43 for switching between connection to the signal line 31 of the cable 3 and connection to the ground line 32. As the switching means 43, a relay switch is used.

Next, the operation and effect of this embodiment will be described. When measuring the characteristic impedance of the printed wiring board 5 using the characteristic impedance measuring instrument 1, the signal pins 41 of the probe 4 are brought into contact with the signal measurement pads 51 of the printed wiring board 5, and the ground pins are measured. 42 is brought into contact with the grounding measurement pad 52 of the printed wiring board 5.
At this time, as shown in FIG.
Are connected to the ground line 32. As a result, the static electricity charged on the signal measuring pad 51 is transferred to the signal pin 41.
Then, the electric charge is gradually reduced via the ground line 32.

Then, as shown in FIG. 3A, the switching means 43 connects the signal pin 41 to the signal line 31, and connects the signal pin 41 between the TDR meter 2 and the printed wiring board 5. Transmission and reception of electrical signals via After the measurement of the characteristic impedance, as shown in FIG. 3B, the connection between the signal pin 41 and the signal line 31 is released by the switching means 43, and the signal pin 41 is connected to the ground line 32. . As a result, the static electricity charged on the signal measurement pad 51 to be measured next is transferred to the signal pin 4.
1 and a state in which the electricity can be gradually reduced through the ground line 32.

As described above, since the characteristic impedance measuring apparatus 1 of the present embodiment has the switching means 43, the signal pin 41 can be connected to the ground line 32 before the measurement is performed. Accordingly, before the measurement of the characteristic impedance, the static electricity charged on the signal measuring pad 51 can be reliably discharged through the signal pin 41 and the ground line 32. When the characteristic impedance is measured, the switching means 43 causes the signal pin 41 to be measured.
By switching the connection to the signal line 31, the measurement can be easily started. Therefore, the characteristic impedance can be measured efficiently.

Embodiment 2 As shown in FIG. 4, this embodiment is an example of a characteristic impedance measuring instrument in which a signal pin 41 and a ground pin 42 are provided so as to be extendable and retractable with respect to a main body 44 of a probe 40. Before the signal pin 41 and the ground pin 42 are measured,
It is in an extended state as shown in FIG. At this time, the signal pins 41 are connected to the ground line 32.

The signal pin 41 and the ground pin 42
4B, as shown in FIG. 4 (B), is brought into a contracted state by abutting against the signal measuring pad 51 and the grounding measuring pad 52 of the printed wiring board 5 during measurement. As a result, the signal pin 41 is connected to the ground line 32.
And the connection to the signal line 31 is released.
Other configurations are the same as those of the first embodiment.

As a result, when the signal pin 41 comes into contact with the signal measuring pad 51 in the extended state (FIG. 4A), the static electricity charged on the signal measuring pad 51 is dissipated. The charge can be gradually reduced via the ground line 32. Next, when the probe 40 is pressed against the printed wiring board 5, the signal pins 41 are contracted and connected to the signal lines 31, so that the characteristic impedance can be measured (FIG. 4B). ).

As described above, since the expansion and contraction mechanism of the signal pin 41 constitutes the switching means 43 as it is, an inexpensive probe 40 with a simple structure can be obtained. In addition,
It has the same function and effect as the first embodiment.

[0024]

As described above, according to the present invention, it is possible to provide a characteristic impedance measuring instrument capable of performing an efficient measurement while reliably reducing the electric charge.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a characteristic impedance measuring instrument according to a first embodiment.

FIG. 2 is an explanatory sectional view of a probe and a printed wiring board according to the first embodiment.

3A is an explanatory diagram of a probe at the time of measurement, and FIG. 3B is an explanatory diagram of a probe before measurement, in the first embodiment.

4A and 4B are explanatory diagrams of a probe before measurement, and FIG. 4B is an explanatory diagram of a probe at the time of measurement in a second embodiment.

FIG. 5 is an explanatory view of a characteristic impedance measuring instrument in a conventional example.

[Explanation of symbols]

 1. . . 1. Characteristic impedance measuring machine, . . 2. TDR meter, . . Cable, 31. . . Signal line, 32. . . Ground wire, 4,40. . . Probe, 41. . . Signal pins, 42. . . Ground pin, 43. . . Switching means, 5. . . Printed wiring board, 51. . . Measurement pad for signal, 52. . . Grounding measurement pad,

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Claims (1)

[Claims] 1. A TDR meter for transmitting and receiving an electric signal to a printed wiring board to measure a characteristic impedance and display a measurement result, and a probe electrically connected to the TDR meter via a cable. In the characteristic impedance measuring instrument, the probe includes a signal pin to be brought into contact with a signal measurement pad electrically connected to the signal layer of the printed wiring board, and a ground electrically connected to a ground layer of the printed wiring board. A grounding pin to be brought into contact with the measurement pad for measurement.
The signal pin is connected to the ground wire of the cable connected to the ground terminal of the DR meter, and the signal pin is connected to the TD.
A characteristic impedance measuring instrument comprising switching means for switching between connection to a signal line of the cable connected to a signal terminal of an R meter and connection to the ground line.