JP2002148290A - Characteristic impedance measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a characteristic impedance measuring instrument, having superior measurement efficiency which can measure multiple signal layers of a multilayered printed wiring board by temporarily arranging a probe at a specific position on the multilayered printed wiring board, when signal pins are arranged so that they can abut against respective corresponding signal measurement pads at a time, and characteristic impedance is measured as to the multiple signal layers of the multilayered printed wiring board. SOLUTION: This characteristic impedance measuring instrument 1 has a TDR meter 11, which sends an electrical signal to the multilayered printed wiring board 3, having a ground layer 32 and multiple signal layers 31 and receives the signal to measure the characteristic impedance and also displays the measurement result and the probe 2, which is electrically connected to the TDR meter 11. The probe 2 has the signal pins 21, which are made to abut against the signal measurement pads, electrically connected to the signal layers 31 of the multilayered printed wiring board 3 and a ground pin 22, which is made to abut against a grounding measurement pad 34 electrically connected to the ground layer 32. The respective signal pins 21 are arranged at a body part 25 of the probe 2, so that they can be made to abut against the respective corresponding signal measurement pads 33 in one time.

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 multilayer printed wiring board.

[0002]

2. Description of the Related Art Conventionally, a characteristic impedance measuring machine 9 as shown in FIG. 13 has been used to measure the characteristic impedance of a multilayer printed wiring board. The characteristic impedance measuring device 9 includes a TDR meter 91 and the TDR meter 91.
A probe 92 electrically connected to the meter 91; The TDR meter 91 transmits and receives an electric signal to and from the printed wiring board 3, measures the characteristic impedance, and displays the measurement result. Also, as shown in FIG.
The probe 92 includes a signal pin 921 and a ground pin 922.
And a pair. Further, the probe 92 is the same as that shown in FIG.
As shown in FIG. 3, it is connected to the TDR meter 91 by a flexible cable 93.

When the characteristic impedance of the multilayer printed wiring board 3 is measured by the characteristic impedance measuring device 9, the signal pin 921 and the ground pin 922 of the probe 92 are provided on the multilayer printed wiring board 3. The electrical signal is transmitted and received between the multilayer printed wiring board 3 and the TDR meter 91 by contacting the pair of measurement pads 39.

[0004]

However, the probe 92 in the characteristic impedance measuring instrument 9 has only one signal pin 921 and one ground pin 922 as shown in FIG. Therefore, when the multilayer printed wiring board 3 has a plurality of signal layers and has a plurality of measurement pads 39 connected to these, respectively, each time the characteristic impedance of each signal layer is measured, , The probe 92 must be moved to bring the signal pin 921 into contact with the corresponding measurement pad 39. Therefore, the characteristic impedance measuring device 9 has a problem that the measurement efficiency is low. In particular, as the number of measurement points on the multilayer printed wiring board 3 increases, the characteristic impedance measurement efficiency decreases.

The present invention has been made in view of such a conventional problem, and an object of the present invention is to provide a characteristic impedance measuring instrument excellent in measurement efficiency.

[0006]

According to a first aspect of the present invention, there is provided a TDR for transmitting and receiving an electric signal to a multilayer printed wiring board having a ground layer and a plurality of signal layers, measuring a characteristic impedance, and displaying a measurement result. In a characteristic impedance measuring instrument having a meter and a probe electrically connected to the TDR meter, the probe is connected to a signal measuring pad electrically connected to each of the signal layers of the multilayer printed wiring board. A plurality of signal pins to be brought into contact with each other, and a ground pin to be brought into contact with a grounding measurement pad electrically connected to the ground layer in the multilayer printed wiring board; The characteristic input terminal is provided on the main body of the probe so that it can be brought into contact with each signal measuring pad at a time. There to-impedance measuring instrument.

It is most remarkable in the present invention that the signal pins are arranged on the main body of the probe so that the signal pins can be brought into contact with the corresponding signal measuring pads at a time. That is. For example, a plurality of signal pins may be erected on the main body of the probe so that their tips are arranged on the same plane.

Next, the function and effect of the present invention will be described.
In measuring the characteristic impedance of the multilayer printed wiring board using the characteristic impedance measuring instrument, for example, the following procedure is employed. First, connect the probe
It is arranged at a predetermined position on the multilayer printed wiring board. That is, each signal pin of the probe is brought into contact with a corresponding signal measurement pad on the multilayer printed wiring board, and each of the ground pins is brought into contact with a corresponding ground measurement pad.

Next, an electric signal is transmitted from the TDR meter to a signal layer to be measured. That is, an electric signal is transmitted through the signal pin which is in contact with the signal measurement pad connected to the signal layer to be measured. Next, the reflected current from the signal layer is received by the TDR meter. The TDR meter measures the reflected voltage,
The reflected waveform is displayed. Then, the TDR meter calculates and displays the characteristic impedance of the signal layer based on the incident voltage of the electric signal transmitted to the multilayer printed wiring board and the reflected voltage.

Next, the characteristic impedance is similarly measured by transmitting and receiving an electric signal to other signal layers in the same manner. By repeating this, the characteristic impedance of each signal layer is measured.

As described above, the probe in the characteristic impedance measuring instrument is arranged so that the signal pins can be brought into contact with the corresponding signal measuring pads at a time. Therefore, when measuring the characteristic impedance of a plurality of signal layers in the multilayer printed wiring board, the probe can be measured in the plurality of signal layers by temporarily disposing the probe at a predetermined position in the multilayer printed wiring board. .
Therefore, it is not necessary to move the probe and contact the signal pin to the corresponding signal measurement pad every time each signal layer is measured.

Therefore, the characteristic impedance of the multilayer printed wiring board can be measured efficiently. Also,
The more measurement points in the multilayer printed wiring board, the higher the measurement efficiency.

As described above, according to the present invention, it is possible to provide a characteristic impedance measuring instrument excellent in measurement efficiency.

Next, as in the second aspect of the present invention, the signal pin is provided so as to be extendable with respect to the main body of the probe, and only a desired signal pin is brought into contact with the signal measuring pad. It is preferable that it is constituted so that it can be performed. Thereby, an accurate characteristic impedance can be measured. In particular, when a plurality of signal layers are arranged adjacent to each other in the multilayer printed wiring board,
That is, it is effective when the ground layer is not interposed between the plurality of signal layers.

That is, the signal pins respectively corresponding to the adjacent signal layers are both brought into contact with the signal measuring pad,
When an electric signal is transmitted to one signal layer and measurement is performed, an error occurs in the measured value because the other signal layer functions in the same manner as the ground layer. Therefore, as in the present invention, only a desired signal pin is brought into contact with the signal measuring pad, whereby
Accurate characteristic impedance can be measured without being affected by other signal layers (see Embodiment 3). As means for expanding and contracting the signal pin,
For example, electromagnetic force or mechanical force can be used.

Next, as in the third aspect of the present invention, the characteristic impedance measuring instrument includes a signal pin and the T pin.
A switch for switching on / off of the electrical connection with the DR meter may be provided. In this case, the characteristic impedance can be measured accurately as in the second aspect of the present invention. As the switch, for example, a relay or a solenoid can be used.

[0017]

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, the characteristic impedance measuring instrument 1 of the present embodiment has a TDR meter 11 and a probe 2 electrically connected to the TDR meter 11. The TDR meter 11 transmits and receives an electric signal to and from the multilayer printed wiring board 3 having the ground layer 32 and the plurality of signal layers 31, measures the characteristic impedance, and displays the measurement result.

As shown in FIG.
It has five signal pins 21 and five ground pins 22.
As shown in FIG. 3, the multilayer printed wiring board 3 is formed by laminating ten conductive layers 38 via an insulating resin layer 37. Of the conductive layers 38, the first, third, fifth, sixth, and eighth layers are the signal layers 31, and the second, fourth, seventh, ninth, and tenth layers are the ground layers 32. . As shown in FIGS. 3 and 4, the signal layers 3 of the multilayer printed wiring board 3 are provided on the first layer, which is the outermost layer of the multilayer printed wiring board 3.
1 and a signal measuring pad 33 electrically connected to each other
And a grounding measuring pad 34 electrically connected to the grounding layer 32.

The signal pin 21 of the probe 2 is shown in FIG.
As shown in FIG. 5, it is brought into contact with the signal measurement pad 33 on the multilayer printed wiring board 3. The ground pin 22 is brought into contact with the ground measurement pad 34.

The signal pins 21 are arranged on the main body 25 of the probe 2 so that they can be brought into contact with the corresponding signal measuring pads 33 at one time. On the other hand, the ground pins 22 are also provided on the main body 25 of the probe 2 so as to be able to contact the corresponding ground measurement pads 34 at a time.

The probe 2 is connected to the TDR meter 11 by a flexible cable 12 as shown in FIG. As shown in FIG. 2, the flexible cable 12 is formed by bundling five coaxial cables 120, and the extension 121 of each coaxial cable 120 is connected to each signal pin 21, and the outside 122 is connected to the ground pin 22. Have been.

As shown in FIGS. 6 and 7, the signal pins 21 are provided so as to be extendable and retractable with respect to the main body 25 of the probe 2, and only the desired signal pins 21 are connected to the signal measuring pad 33. It is configured to be able to contact. An electromagnetic force is used as a means for expanding and contracting the signal pin 21.

For example, when measuring the fifth signal layer 315 in the multilayer printed wiring board 3, FIG.
As shown in FIG. 7A, the signal pin 215 corresponding to the fifth signal layer 315 is extended to
Is brought into contact with the signal measurement pad 335 which is connected to. Then, the other signal pins 211, 213, 216 and 218 are contracted and separated from the signal measuring pad 33. Further, the ground pins 32 are brought into contact with the corresponding ground measurement pads 34. This is because even if the ground pin 32 is in contact with the ground measurement pad 34, the measured value is not particularly affected.

Next, when measuring the signal layer 316 of the sixth layer, as shown in FIG.
The signal pin 216 corresponding to the signal layer 316 is extended and brought into contact with the signal measurement pad 336 connected to the signal layer 316. Then, the other signal pins 211, 213, 215, 2
18 is shrunk away from the signal measuring pad 33.

Next, the operation and effect of this embodiment will be described. In measuring the characteristic impedance of the multilayer printed wiring board 3 using the characteristic impedance measuring device 1, the following procedure is employed. First, the probe 2 is arranged at a position on the multilayer printed wiring board 3 where the test pattern 35 is formed. That is, each signal pin 21 of the probe 2 is brought into contact with a corresponding signal measurement pad 33 of the multilayer printed wiring board 3, and the ground pin 22 is brought into contact with a corresponding ground measurement pad 34.

Next, in the signal layer 31 to be measured,
An electric signal is transmitted from the TDR meter 11. That is,
An electric signal is transmitted through the signal pin 21 which is in contact with the signal measurement pad 33 connected to the signal layer 31 to be measured. Next, the reflected current from the signal layer 31 is received by the TDR meter 11. The TDR meter 11 measures the reflected voltage and displays the reflected waveform. Then, the TDR meter 11 calculates and displays the characteristic impedance of the signal layer 31 based on the incident voltage of the electric signal transmitted to the multilayer printed wiring board 3 and the reflected voltage.

Next, the characteristic signal is similarly measured by transmitting and receiving the electric signal to the other signal layers 31 in the same manner. By repeating this, each signal layer 31
Measure the characteristic impedance for.

As described above, the probe 2 of the characteristic impedance measuring instrument 1 connects each of the signal pins 21 to
They are arranged so that they can be brought into contact with the corresponding signal measuring pads 33 at a time. for that reason,
When measuring the characteristic impedance of the plurality of signal layers 31 in the multilayer printed wiring board 3, the probe 2 is moved to a predetermined position on the multilayer printed wiring board 3,
That is, by arranging once at the position of the test pattern 35, it is possible to measure the plurality of signal layers 31. Therefore, it is not necessary to move the probe 2 every time each signal layer 31 is measured and to make the signal pins 21 contact the corresponding signal measurement pads 33.

Therefore, the characteristic impedance of the multilayer printed wiring board 3 can be measured efficiently. Also, the more measurement points on the multilayer printed wiring board 3, the higher the measurement efficiency.

The signal pins 31 are provided so as to be extendable with respect to the main body 25 of the probe 2 so that only the desired signal pins 21 can be brought into contact with the signal measuring pads 33. It is. Thereby, an accurate characteristic impedance can be measured. In particular, in the multilayer printed wiring board 3, the measurement is performed on the fifth signal layer 315 and the sixth signal layer 316 in which the plurality of signal layers 31 are arranged adjacent to each other and the ground layer 32 is not interposed therebetween. This is effective (see Embodiment 3).

As described above, according to the present embodiment, it is possible to provide a characteristic impedance measuring instrument excellent in measurement efficiency.

Embodiment 2 As shown in FIGS. 8 and 9, the present embodiment employs a signal pin 21 and a TD.
This is an example of a characteristic impedance measuring instrument having a switch 26 for switching on / off of electrical connection with the R meter 11.

That is, as shown in FIG. 8, the signal pin 2 of the probe 20 in the characteristic impedance measuring instrument is used.
1 and the ground pin 22 are respectively connected to the TDR meter 1
1 and the outside line 1 of the coaxial cable connected to
22. And, between the extension 121 and the signal pin 21, the switch 26 formed of a relay is provided.
Are provided in the probe 20.

In measuring the characteristic impedance of the multilayer printed wiring board 3, first, the probe 20 is arranged at the position of the test pattern 35 as shown in FIG. The signal pins 21 and the ground pins 22 of the probe 20 are connected to the corresponding signal measurement pads 33, respectively.
And the grounding measurement pad 34.

In this state, for example, when measuring the fifth signal layer 315 in the multilayer printed wiring board 3, as shown in FIG. 9, the switch 265 is turned on to correspond to the signal layer 315. Signal pin 2
15 is connected to the extension 121 of the coaxial cable 120. Then, the other signal pins 211, 213, 216, 2
With regard to 18, the switches 261, 263, 266, 2
The connection with the extension 121 is cut off by cutting 68.

Next, when measuring the sixth signal layer 316, by turning on the switch 266,
The signal pin 216 corresponding to the signal layer 316 is connected to the extension 121 of the coaxial cable 120. Then, the other signal pins 211, 213, 215, and 218 turn off the switches 261, 263, 265, and 268, and
Disconnect with. Other configurations are the same as those of the first embodiment.

Also in this case, the signal layer 3 to be measured
Since only 1 can be connected to the TDR meter 11, accurate characteristic impedance can be measured as in the first embodiment. Others have the same operation and effects as those of the first embodiment.

Third Embodiment As shown in FIGS. 10 to 12, this embodiment relates to the fifth and sixth signal layers 315 and 316 in the multilayer printed wiring board 3 shown in the first embodiment. This is an example in which characteristic impedance was measured using the characteristic impedance measuring instrument 1 of Example 1. The reference numerals in this example represent the same elements as those used in the first embodiment.

The characteristic impedance is measured when only the signal pin 21 corresponding to the signal layer 31 to be measured is brought into contact with the signal measuring pad 33 (FIG. 11A, FIG. 12).
(A)) and when all the signal pins 31 are brought into contact with the signal measuring pad 33 (FIG. 11B, FIG. 12).
(B)). The grounding pin 22
In all cases, all the ground pins 22 were in contact with the ground measurement pad 34.

The fifth and sixth signal layers 315, 31
Numeral 6 denotes adjacent signal layers as shown in FIG. 10, and there is no ground layer 32 between them. First, the fifth signal layer 31
5 was measured. That is, the characteristic impedance was measured by bringing only the signal pin 215 into contact with the signal measurement pad 335 (see FIGS. 6 and 7A). Next, all the signal pins 21 were brought into contact with the signal measuring pad 33 to measure the characteristic impedance of the fifth signal layer 315 (see FIG. 5).

Next, measurement was performed on the sixth signal layer 316. That is, the characteristic impedance was measured by bringing only the signal pin 216 into contact with the signal measurement pad 336 (see FIG. 7B). Next, all the signal pins 21 are brought into contact with the signal measuring pads 33 to thereby form the sixth signal layer 3.
Sixteen characteristic impedances were measured (see FIG. 5). Other measurement methods are the same as in the first embodiment.

The measurement result of the characteristic impedance is
This is shown in FIGS. That is, among the measurement results of the fifth signal layer 315, the signal pin 2 corresponding to the signal layer 315
A measurement result when only 15 is brought into contact with the signal measurement pad 335 is shown by a curve A in FIG. 11A, and a measurement result when all the signal pins 31 are brought into contact with the signal measurement pad 33 is shown. This is shown by curve B in FIG.

FIG. 12A shows a measurement result when only the signal pin 216 corresponding to the signal layer 316 is brought into contact with the signal measurement pad 336 among the measurement results of the sixth signal layer 316. FIG. 1 shows a measurement result when all the signal pins 31 are brought into contact with the signal measurement pad 33.
This is shown in curve D of 2 (B). In addition, FIG.
12 (B) and FIGS. 12 (A) and 12 (B), the range T of the curves A to D shown in each drawing is used as the measured value.
Part.

As can be seen from FIGS. 11 and 12, the fifth
In all of the signal layers 31 of the sixth layer and the sixth layer, all the signal pins 21 are used for signal compared to the case where only the signal pin 21 corresponding to the signal layer 31 to be measured is brought into contact with the signal measuring pad 33. It can be seen that when the measurement is carried out in contact with the measurement pad 33, the measured value decreases by about 5Ω.

The signal pins 21 corresponding to the adjacent signal layers 31 are connected to the signal measuring pads 33, respectively.
It is considered that when an electrical signal is transmitted to one of the signal layers 31 and measurement is performed while the other signal layer 31 is in contact with the ground layer, an error occurs in the measured value because the other signal layer 31 performs the same function as the ground layer. .

According to the results of this example, by bringing only the signal pin 21 corresponding to the signal layer 31 to be measured into contact with the signal measuring pad 33, accurate measurement can be performed without being affected by other signal layers 31. It can be seen that a characteristic impedance can be measured.

[0047]

As described above, according to the present invention, it is possible to provide a characteristic impedance measuring instrument excellent in measurement efficiency.

[Brief description of the drawings]

FIG. 1 is a perspective view of a characteristic impedance measuring instrument and a multilayer printed wiring board according to a first embodiment.

FIG. 2 is a perspective view of a probe according to the first embodiment.

FIG. 3 is an explanatory cross-sectional view of the multilayer printed wiring board according to the first embodiment.

FIG. 4 is a plan view of a test pattern of a probe and a multilayer printed wiring board in the first embodiment.

FIG. 5 is a perspective view showing a state in which probes are arranged on a test pattern of the multilayer printed wiring board in the first embodiment.

FIG. 6 is a perspective view of a test pattern of a probe and a multilayer printed wiring board when measuring a fifth signal layer in the first embodiment.

FIGS. 7A and 7B are cross-sectional explanatory views of a probe when measuring a fifth signal layer in the first embodiment, and FIG.
Sectional explanatory drawing of the probe at the time of measuring about the 6th signal layer.

FIG. 8 is an explanatory sectional view of a plane perpendicular to the longitudinal direction of a probe according to a second embodiment.

FIG. 9 is an explanatory cross-sectional view of a test pattern of a probe and a multilayer printed wiring board when measuring a fifth signal layer in the second embodiment.

FIG. 10 is an explanatory cross-sectional view illustrating the periphery of a fifth signal layer and a sixth signal layer of the multilayer printed wiring board according to the third embodiment.

FIG. 11A shows a measurement result of the characteristic impedance of the fifth signal layer when only the signal pin corresponding to the signal layer to be measured is brought into contact with the signal measurement pad in the third embodiment; 5) Diagrams showing measurement results of the characteristic impedance of the fifth signal layer when all signal pins are brought into contact with the signal measurement pad.

FIG. 12A shows a measurement result of the characteristic impedance of the sixth signal layer when only the signal pin corresponding to the signal layer to be measured is brought into contact with the signal measurement pad in the third embodiment; 7) Diagrams respectively showing measurement results of the characteristic impedance of the sixth signal layer when all signal pins are brought into contact with the signal measurement pad.

FIG. 13 is a perspective view of a characteristic impedance measuring instrument and a multilayer printed wiring board in a conventional example.

FIG. 14 is a front view of a probe in a conventional example.

[Explanation of symbols]

1. . . 10. Characteristic impedance measuring instrument, . . TDR meter, 2, 20. . . Probes, 21, 211, 213, 215, 216, 218. . .
Signal pins, 22. . . Ground pin, 25. . . Main body, 3. . . Multilayer printed wiring board, 31, 311, 313, 315, 316, 318. . .
Signal layer, 32. . . Ground layer, 33,331,333,335,336,338. . .
Measurement pad for signal, 34. . . Grounding measurement pad,

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H05K 3/46 H05K 3/46 WF Term (Reference) 2G011 AA03 AA15 AB07 AC02 AC31 AF01 2G028 AA01 BB10 BC01 CG08 DH11 FK00 HM05 HM07 HN01 HN12 LR09 5E317 AA02 BB01 CD29 CD36 GG16 5E346 AA12 AA15 BB01 BB02 BB03 BB04 BB06 BB16 CC31 GG32 GG34 HH01 HH33

Claims (3)

[Claims] 1. A TDR meter for transmitting and receiving an electric signal to a multilayer printed wiring board having a ground layer and a plurality of signal layers, measuring a characteristic impedance and displaying a measurement result, and electrically connecting the TDR meter to the TDR meter. In the characteristic impedance measuring instrument having a probe connected thereto, the probe comprises a plurality of signal pins which are brought into contact with a signal measuring pad electrically connected to each of the signal layers of the multilayer printed wiring board; A grounding pin for contacting a grounding measurement pad electrically connected to the grounding layer of the printed wiring board, and wherein each of the signal pins is in contact with each of the corresponding signal measurement pads at one time. A characteristic impedance measuring instrument, which is provided on a main body of the probe so as to be able to perform the measurement. 2. The signal pin according to claim 1, wherein the signal pin is provided so as to be expandable and contractable with respect to the main body of the probe, and only a desired signal pin can be brought into contact with the signal measuring pad. A characteristic impedance measuring instrument, characterized in that: 3. The characteristic impedance measuring device according to claim 1, wherein the characteristic impedance measuring device includes a switch for switching on / off of an electrical connection between the signal pin and the TDR meter.