Crosstalk measurement method and crosstalk measurement probe

Abstract

The crosstalk measurement method includes: a step of preparing a printed wiring board having a first signal pattern, a second signal pattern, and a ground pattern, the first signal pattern and the second signal pattern being arranged at intervals in a first direction and extending in a second direction orthogonal to the first direction, the ground pattern is disposed between the first signal pattern and the second signal pattern in the first direction and extends along the second direction. A step of preparing a probe having a first probe, a second probe, and a shield plate formed of a conductive material; and a step for measuring crosstalk between the first signal pattern and the second signal pattern. The first probe and the second probe each have a tip end and a base end, and the base end is an end on the opposite side from the tip end. The top end of the first probe and the top end of the second probe are in contact with the first signal pattern and the second signal pattern respectively.

Description

Technical Field

[0001] The present disclosure relates to a crosstalk measurement method and a crosstalk measurement probe. This application claims priority based on Japanese patent application No. 2022-095734 filed on June 14, 2022. All the contents described in the Japanese patent application are incorporated herein by reference. Background Art

[0002] For example, Japanese Patent Publication No. 2019-62114 (Patent Document 1) describes a printed wiring board. The printed wiring board described in Patent Document 1 has a base film, a first signal pattern, a second signal pattern, and a ground pattern. The base film has a main surface. The first signal pattern, the second signal pattern, and the ground pattern are arranged on the main surface of the base film.

[0003] The first signal pattern and the second signal pattern are arranged at intervals in a first direction and extend in a second direction orthogonal to the first direction. The ground pattern is arranged between the first signal pattern and the second signal pattern in the first direction. In the printed wiring board described in Patent Document 1, crosstalk sometimes occurs between a signal flowing in the first signal pattern and a signal flowing in the second signal pattern.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2019-62114 Summary of the invention

[0007] The crosstalk measurement method disclosed in the present invention comprises: a process of preparing a printed wiring board, the printed wiring board having a first signal pattern, a second signal pattern and a ground pattern, the first signal pattern and the second signal pattern being arranged at intervals in a first direction and extending in a second direction orthogonal to the first direction, and the ground pattern being arranged between the first signal pattern and the second signal pattern in the first direction and extending in the second direction; a process of preparing a probe, the probe having a first probe, a second probe and a shielding plate formed of a conductive material; and a process of measuring the crosstalk between the first signal pattern and the second signal pattern. The first probe and the second probe each have a top and a base end, and the base end is an end on the side opposite to the top end. The top end of the first probe and the top end of the second probe are in contact with the first signal pattern and the second signal pattern, respectively. The shielding plate extends along a plane orthogonal to the first direction and has an upper end and a lower end in a third direction orthogonal to the first direction and the second direction, and the lower end is an end on the side opposite to the upper end and is in contact with the ground pattern. The shielding plate is located between the first probe and the second probe in the first direction. The thickness of the shielding plate is greater than the skin depth corresponding to the electromagnetic wave having the same frequency as the signals flowing in the first signal pattern and the second signal pattern. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a top view of the printed wiring board 10 .

[0009] Figure 2 yes Figure 1 Cross-sectional view at II-II in FIG.

[0010] Figure 3 It is a perspective view of the crosstalk measurement probe 20 .

[0011] Figure 4 It is a side view of the crosstalk measurement probe 20 .

[0012] Figure 5 It is a process diagram of the crosstalk measurement method involved in the embodiment.

[0013] Figure 6 It is a plan view of a printed wiring board 10 according to a modification.

[0014] Figure 7 It is a side view of the crosstalk measurement probe 20 according to the first modification.

[0015] Figure 8 It is a side view of the crosstalk measurement probe 20 according to the second modification.

[0016] Fig. 9 It is a perspective view of a crosstalk measurement probe 20 according to Modification 3.

[0017] Fig.10 It is a side view of the crosstalk measurement probe 20 according to the third modification.

[0018] Fig.11 1 is a graph showing the relationship between the frequency of the differential signal flowing through the signal pattern 12 a and the signal pattern 12 b and the amount of crosstalk of the differential component to the signal pattern 13 a and the signal pattern 13 b . DETAILED DESCRIPTION

[0019] [Technical Problems to be Solved by the Present Disclosure]

[0020] In order to measure the crosstalk as described above, a crosstalk measurement probe is used. The crosstalk measurement probe has a first probe and a second probe. The first probe and the second probe each have a tip. The tip of the first probe and the tip of the second probe are in contact with the first signal pattern and the second signal pattern, respectively.

[0021] However, when one wants to use such a crosstalk measurement probe to measure the crosstalk between a signal flowing in a first signal pattern and a signal flowing in a second signal pattern, crosstalk may occur between the first probe and the second probe, resulting in a decrease in the measurement accuracy of the crosstalk between the signal flowing in the first signal pattern and the signal flowing in the second signal pattern.

[0022] The present disclosure is made in view of the above-mentioned problems in the prior art. More specifically, the present disclosure provides a crosstalk measurement method capable of improving the measurement accuracy of crosstalk.

[0023] [Effects of the present disclosure]

[0024] According to the crosstalk measurement method of the present disclosure, it is possible to improve the measurement accuracy of crosstalk.

[0025] [Description of Embodiments of the Present Disclosure]

[0026] First, implementation aspects of the present disclosure are listed for description.

[0027] (1) The crosstalk measurement method according to the embodiment comprises: a step of preparing a printed wiring board, the printed wiring board having a first signal pattern, a second signal pattern, and a ground pattern, the first signal pattern and the second signal pattern being arranged at intervals in a first direction and extending in a second direction orthogonal to the first direction, the ground pattern being arranged between the first signal pattern and the second signal pattern in the first direction and extending in the second direction; a step of preparing a probe, the probe having a first probe, a second probe, and a shielding plate formed of a conductive material; and a step of measuring the crosstalk between the first signal pattern and the second signal pattern. The first probe and the second probe each have a top end and a base end, the base end being an end on the side opposite to the top end. The top end of the first probe and the top end of the second probe are in contact with the first signal pattern and the second signal pattern, respectively. The shielding plate extends along a plane orthogonal to the first direction and has an upper end and a lower end in a third direction orthogonal to the first direction and the second direction, the lower end being an end on the side opposite to the upper end and in contact with the ground pattern. The shielding plate is located between the first probe and the second probe in the first direction. The thickness of the shielding plate is greater than the skin depth corresponding to the electromagnetic wave having the same frequency as the signals flowing in the first signal pattern and the second signal pattern.

[0028] According to the crosstalk measurement method of (1) above, the crosstalk measurement accuracy can be improved.

[0029] (2) In the crosstalk measurement method of (1) above, the upper end may be located above the base end of the first probe and the base end of the second probe in the third direction.

[0030] According to the crosstalk measurement method of (2) above, the crosstalk measurement accuracy can be further improved.

[0031] (3) In the crosstalk measurement method of (1) or (2), the shielding plate may have a rear end and a front end in the second direction, the front end being the end opposite to the rear end. The front end may be located at a position protruding in the second direction by 0.5 mm or more and 5 mm or less than the tip of the first probe and the tip of the second probe.

[0032] According to the crosstalk measurement method of (3) above, the crosstalk measurement accuracy can be further improved.

[0033] (4) In the crosstalk measurement methods of (1) to (3), the shield plate may have a plurality of protrusions at the lower end that are arranged at intervals along the second direction and contact the ground pattern. The pitch between two adjacent protrusions of the plurality of protrusions may be 0.4 mm or less.

[0034] According to the crosstalk measurement method of (4) above, it is possible to easily obtain electrical contact between the shield plate and the ground pattern while improving the crosstalk measurement accuracy.

[0035] (5) In the crosstalk measurement method of (4) above, the height of each of the plurality of protrusions may be 0.5 mm or less.

[0036] According to the crosstalk measurement method of (5) above, it is possible to easily obtain electrical contact between the shield plate and the ground pattern while improving the measurement accuracy of the crosstalk.

[0037] (6) The crosstalk measurement probe involved in the embodiment includes a first probe, a second probe, and a shielding plate formed of a conductive material. The first probe and the second probe each have a top and a base, and the base is the end on the side opposite to the top. The top of the first probe and the top of the second probe are arranged at intervals in the first direction. The shielding plate extends along a plane orthogonal to the first direction and is located between the first probe and the second probe in the first direction. The thickness of the shielding plate can also be greater than the skin depth corresponding to the electromagnetic wave having a frequency equal to the signal flowing in the first probe and the second probe.

[0038] According to the crosstalk measurement probe of (6) above, the crosstalk measurement accuracy can be improved.

[0039] (7) In the crosstalk measurement probe of (6) above, the shielding plate may have a rear end and a front end in a second direction orthogonal to the first direction, the front end being an end on a side opposite to the rear end. The front end may also be located at a position protruding in the second direction by 0.5 mm or more and 5 mm or less than the top end of the first probe and the top end of the second probe.

[0040] According to the crosstalk measurement probe of (7) above, the crosstalk measurement accuracy can be further improved.

[0041] (8) In the crosstalk measurement probe of (7) above, the shielding plate may have an upper end and a lower end in a third direction orthogonal to the first direction and the second direction, and may have a plurality of protrusions arranged at intervals along the second direction at the lower end, the lower end being the end on the side opposite to the upper end.

[0042] According to the crosstalk measurement probe of (8) above, electrical contact between the shield plate and the ground pattern can be easily achieved.

[0043] (9) In the crosstalk measurement probe of (8) above, a pitch between two adjacent protrusions among the plurality of protrusions may be 0.4 mm or less.

[0044] According to the crosstalk measurement probe of (9) above, it is possible to easily obtain electrical contact between the shield plate and the ground pattern while improving the measurement accuracy of the crosstalk.

[0045] (10) In the crosstalk measurement probe of (8) or (9) above, the height of each of the plurality of protrusions may be 0.5 mm or less.

[0046] According to the crosstalk measurement probe of (10) above, it is possible to easily obtain electrical contact between the shield plate and the ground pattern while improving the crosstalk measurement accuracy.

[0047] (11) In the crosstalk measurement probe of (6) or (7), the shielding plate may have an upper end and a lower end in a third direction orthogonal to the first direction and the second direction, the lower end being the end opposite to the upper end. The upper end may be located above the base end of the first probe and the base end of the second probe in the third direction.

[0048] According to the crosstalk measurement probe of (11) above, the crosstalk measurement accuracy can be further improved.

[0049] [Details of the embodiments of the present disclosure]

[0050] Next, the details of the embodiments of the present disclosure will be described with reference to the accompanying drawings. In the following drawings, the same reference numerals are used for the same or corresponding parts, and repeated descriptions are not repeated. The printed wiring board to be measured for crosstalk is set to printed wiring board 10. The crosstalk measurement probe involved in the embodiment is set to crosstalk measurement probe 20.

[0051] (Structure of Printed Wiring Board 10)

[0052] Hereinafter, the structure of the printed wiring board 10 will be described.

[0053] Figure 1 It is a top view of the printed wiring board 10 . Figure 2 yes Figure 1The cross-sectional view at II-II in FIG. Figure 1 and Figure 2 As shown, the printed wiring board 10 has a base film 11 , signal patterns 12 a and 12 b , signal patterns 13 a and 13 b , ground patterns 14 a , 14 b and 14 c , a ground pattern 15 , and a conductor layer 16 .

[0054] The base film 11 has a first surface 11a and a second surface 11b. The first surface 11a and the second surface 11b are end surfaces in the thickness direction of the base film 11. The second surface 11b is a surface opposite to the first surface 11a. The base film 11 is formed of, for example, fluororesin. However, the base film 11 may also be formed of a material other than fluororesin.

[0055] The signal patterns 12a, 12b, 13a, and 13b are arranged on the first surface 11a. The signal patterns 12a, 12b, 13a, and 13b are arranged at intervals in a first direction DR1. The first direction DR1 is one of the directions orthogonal to the normal direction of the first surface 11a.

[0056] The signal pattern 12a, the signal pattern 12b, the signal pattern 13a, and the signal pattern 13b extend along the second direction DR2. The second direction DR2 is a direction orthogonal to the first direction DR1.

[0057] The signal pattern 12b and the signal pattern 13a are located between the signal pattern 12a and the signal pattern 13b in the first direction DR1. The signal pattern 12b is located between the signal pattern 12a and the signal pattern 13a in the first direction DR1. That is, the signal pattern 12a, the signal pattern 12b, the signal pattern 13a, and the signal pattern 13b are arranged in sequence from one side in the first direction DR1 to the other side in the first direction DR1.

[0058] The signal flowing in the signal pattern 12a is in opposite phase to the signal flowing in the signal pattern 12b. The signal flowing in the signal pattern 13a is in opposite phase to the signal flowing in the signal pattern 13b. That is, the signal pattern 12a and the signal pattern 12b form a pair of differential signal lines, and the signal pattern 13a and the signal pattern 13b form a pair of differential signal lines.

[0059] The ground pattern 14a, the ground pattern 14b, and the ground pattern 14c are arranged on the first surface 11a. The ground pattern 14a is arranged between the signal pattern 12b and the signal pattern 13a so as to be separated from the signal pattern 12b and the signal pattern 13a in the first direction DR1.

[0060] The ground pattern 14b is adjacent to the signal pattern 12a on the side opposite to the signal pattern 12b and separated from the signal pattern 12a in the first direction DR1. The ground pattern 14c is adjacent to the signal pattern 13b on the side opposite to the signal pattern 13a and separated from the signal pattern 13b in the first direction DR1.

[0061] The ground pattern 15 is arranged on the second surface 11b. The ground pattern 15 is arranged on the entire surface of the second surface 11b. The ground pattern 15 is set to a ground potential.

[0062] A plurality of through holes 11c are formed in the base film 11. When viewed from above, the plurality of through holes 11c overlap with the ground pattern 14a. The plurality of through holes 11c are arranged at intervals along the second direction DR2. When viewed from above, the through holes 11c are, for example, circular. The through holes 11c penetrate the base film 11 along the thickness direction. A conductor layer 16 is disposed in the through holes 11c. Thus, the ground pattern 14a is electrically connected to the ground pattern 15 and is set to a ground potential.

[0063] A plurality of through holes 11d and a plurality of through holes 11e may be further formed in the base film 11. When viewed from above, the plurality of through holes 11d overlaps with the ground pattern 14b and is arranged at intervals along the second direction DR2. When viewed from above, the plurality of through holes 11e overlaps with the ground pattern 14c and is arranged at intervals along the second direction DR2. The through holes 11d and the through holes 11e are, for example, circular when viewed from above, and penetrate the base film 11 in the thickness direction. The conductor layer 17 and the conductor layer 18 are respectively arranged in the through hole 11d and the through hole 11e. Thus, the ground pattern 14b and the ground pattern 14c are electrically connected to the ground pattern 15 and are set to the ground potential.

[0064] It should be noted that the signal pattern 12a, the signal pattern 12b, the signal pattern 13a, the signal pattern 13b, the ground pattern 14a, the ground pattern 14b, the ground pattern 14c, the ground pattern 15, the conductor layer 16, the conductor layer 17, and the conductor layer 18 are formed of, for example, copper. However, the signal pattern 12a, the signal pattern 12b, the signal pattern 13a, the signal pattern 13b, the ground pattern 14a, the ground pattern 14b, the ground pattern 14c, the ground pattern 15, the conductor layer 16, the conductor layer 17, and the conductor layer 18 may be formed of a conductive material other than copper.

[0065] (Structure of the crosstalk measurement probe 20)

[0066] Figure 3 2 is a perspective view of the crosstalk measurement probe 20. Figure 3 As shown, the crosstalk measurement probe 20 includes a plurality of probes 30 and a shield plate 40 .

[0067] The stylus 30 has a tip 30a and a base end 30b. The base end 30b is an end on the side opposite to the tip 30a. The direction perpendicular to the first direction DR1 and the second direction DR2 is set as the third direction DR3. It should be noted that the third direction DR3 is consistent with the normal direction of the first surface 11a. The stylus 30 extends obliquely relative to the surface perpendicular to the third direction DR3 in such a way that the base end 30b is located above the tip 30a in the third direction DR3. The tips 30a of the plurality of stylus needles 30 are arranged at intervals in the first direction DR1.

[0068] The probe 30 whose tip 30a contacts the signal pattern 12a and the probe 30 whose tip 30a contacts the signal pattern 12b are respectively referred to as probe 31 and probe 32. The probe 30 whose tip 30a contacts the signal pattern 13a and the probe 30 whose tip 30a contacts the signal pattern 13b are respectively referred to as probe 33 and probe 34.

[0069] The stylus 30 whose tip 30a contacts the ground pattern 14a is referred to as stylus 35 and stylus 36. It should be noted that stylus 35 is located closer to stylus 32 than stylus 36. The stylus 30 whose tip 30a contacts the ground pattern 14b and the stylus 30 whose tip 30a contacts the ground pattern 14c are referred to as stylus 37 and stylus 38, respectively.

[0070] Although not shown, the base ends 30b of the probes 31, 32, 33, and 34 are connected to the center conductor of the coaxial cable. The coaxial cable is connected to a high-frequency signal source. Probes 35, 36, 37, and 38 are connected to the outer conductor of the coaxial cable. The outer conductor of the coaxial cable is preferably set to ground potential.

[0071] The shielding plate 40 is formed of a conductive material. The shielding plate 40 is formed of, for example, aluminum, copper, stainless steel, chromium, beryllium copper, or phosphor bronze. However, the shielding plate 40 may be formed of a conductive material other than these. The surface of the shielding plate 40 may be plated with gold or coated with a magnetic material. The shielding plate 40 extends along a plane orthogonal to the first direction DR1. The shielding plate 40 is disposed between the measuring needle 32 and the measuring needle 33 in the first direction DR1. More specifically, the shielding plate 40 is disposed between the measuring needle 35 and the measuring needle 36 in the first direction DR1. The shielding plate 40 is fixed to the measuring needle 35 and the measuring needle 36, for example. The fixing is performed, for example, by soldering.

[0072] Figure 4 FIG. 2 is a side view of the crosstalk measurement probe 20. Figure 4 In FIG. 1 , the illustration of the plurality of measuring needles 30 is omitted. Figure 4 The printed wiring board 10 is also shown in the figure. Figure 4 As shown, the shielding plate 40 is a plate-shaped member and has a rectangular shape when viewed from the side.

[0073] The shielding plate 40 has an upper end 40a and a lower end 40b in the third direction DR3. The lower end 40b is an end on the side opposite to the upper end 40a. The shielding plate 40 contacts the ground pattern 14a at the lower end 40b. For this reason, the shielding plate 40 is set to the ground potential. The position of the base end 30b of the probe 32 and the probe 33 in the third direction DR3 is set to position P1. Preferably, the upper end 40a is located at a position higher than the position P1 in the third direction DR3.

[0074] The shielding plate 40 has a front end 40c and a rear end 40d in the second direction DR2. The rear end 40d is an end on the side opposite to the front end 40c. The position of the tip 30a of the measuring needle 32 and the measuring needle 33 in the second direction DR2 is set to position P2. The position of the base end 30b of the measuring needle 32 and the measuring needle 33 in the second direction DR2 is set to position P3. The front end 40c is located at a position protruding from position P2 in the second direction DR2. The rear end 40d is located at a position protruding from position P3 in the second direction DR2.

[0075] The distance between the position P2 and the front end 40c in the second direction DR2 is defined as a distance DIS. The distance DIS is preferably 0.5 mm or more and 5 mm or less. The thickness of the shielding plate 40 is defined as a thickness T (see Figure 3 The thickness T is preferably greater than the skin depth corresponding to the electromagnetic waves released from the probes 31 , 32 , 33 , and 34 .

[0076] It should be noted that the skin depth varies according to the magnetic permeability and electrical conductivity of the constituent material of the shielding plate 40 in addition to the frequency of the electromagnetic waves released from the stylus 31, 32, 33, and 34. It should be noted that the frequency of the electromagnetic waves released from the stylus 31, 32, 33, and 34 is equal to the frequency of the signal flowing in the signal pattern 12a, 12b, 13a, and 13b (the frequency of the signal flowing in the stylus 31, 32, 33, and 34).

[0077] (Crosstalk Measurement Method According to Embodiment)

[0078] Hereinafter, a crosstalk measurement method according to an embodiment will be described.

[0079] Figure 5 is a process diagram of a crosstalk measurement method according to an embodiment of the present invention. Figure 5 As shown, the crosstalk measurement method according to the embodiment includes a preparation step S1 and a crosstalk measurement step S2. The preparation step S1 includes a first step S11 and a second step S12.

[0080] In the first step S11, the printed wiring board 10 is prepared. In the second step S12, the crosstalk measurement probe 20 is prepared.

[0081] The crosstalk measurement step S2 is performed after the preparation step S1. In the crosstalk measurement step S2, first, the tip 30a of the probe 31 and the tip 30a of the probe 32 are in contact with the end of the signal pattern 12a and the end of the signal pattern 12b, respectively, and the tip 30a of the probe 33 and the tip 30a of the probe 34 are in contact with the end of the signal pattern 13a and the end of the signal pattern 13b, respectively. At this time, the tip 30a of the probe 35 and the tip 30a of the probe 36 are in contact with the ground pattern 14a, and the tip 30a of the probe 37 and the tip 30a of the probe 38 are in contact with the ground pattern 14b and the ground pattern 14c, respectively.

[0082] In the crosstalk measurement step S2, secondly, the differential signal flows through the probe 31 and the probe 32. As a result, the differential signal flows through the signal pattern 12a and the signal pattern 12b, but a part of the differential signal is transferred to the signal pattern 13a, the signal pattern 13b, the probe 33, and the probe 34. In this state, the crosstalk is measured by taking the ratio of the intensity of the signal input to the probe 31 and the probe 32 and the intensity of the signal output from the probe 33 and the probe 34.

[0083] (Variation Example)

[0084] Figure 6 FIG. 1 is a top view of a printed wiring board 10 according to a modified example. Figure 6 As shown, the printed wiring board 10 may not have the signal pattern 12a and the signal pattern 13b. In this case, the signal pattern 12b and the signal pattern 13a are each a single-ended signal line. In this case, the crosstalk measurement probe 20 does not need to have the probe pins 31, 34, 37, and 38.

[0085] Figure 7 FIG. 2 is a side view of a crosstalk measurement probe 20 according to Modification 1. Figure 7 In FIG. 1 , the illustration of the plurality of measuring needles 30 is omitted. Figure 7 In the figure, the printed wiring board 10 is also shown. Figure 7 As shown, the shield plate 40 may also have a plurality of protrusions 41 formed at the lower end 40 b and may also be in contact with the ground pattern 14 a at the plurality of protrusions 41 .

[0086] The plurality of protrusions 41 are arranged at intervals in the second direction DR2. The pitch between two adjacent protrusions 41 is set to a pitch P. The pitch P is preferably 0.4 mm or less. The height of the protrusion 41 is set to a height H. The height H is preferably 0.5 mm or less.

[0087] Figure 8 FIG. 2 is a side view of a crosstalk measurement probe 20 according to Modification 2. Figure 8 In FIG. 1 , the illustration of the plurality of measuring needles 30 is omitted. Figure 8 In the figure, the printed wiring board 10 is also shown. Figure 8 As shown, the shielding plate 40 may not be rectangular in a side view. For example, the shielding plate 40 may be chamfered at the corners of the side on the front end 40c side in a side view and the side on the upper end 40a side in a side view.

[0088] Fig. 9 FIG. 2 is a perspective view of a crosstalk measurement probe 20 according to Modification 3. Fig. 9 As shown, the crosstalk measurement probe 20 may also include a spring member 51 and a spring member 52. The spring member 51 and the spring member 52 are respectively attached to the probe 35 and the probe 36. The shielding plate 40 is sandwiched by the spring member 51 and the spring member 52 and can slide between the spring member 51 and the spring member 52. The shielding plate 40 is urged toward the printed wiring board 10 side by the spring member 51 and the spring member 52.

[0089] Fig.10 FIG. 2 is a side view of a crosstalk measurement probe 20 according to Modification 3. Fig.10 In FIG. 1 , the illustration of the plurality of measuring needles 30 is omitted. Fig.10 In the figure, the printed wiring board 10 is also shown. Fig.10 As shown, the protrusion 41 may have elasticity. That is, the protrusion 41 may be configured to be elastically deformed by contact with the ground pattern 14b.

[0090] (Effects of the crosstalk measurement method according to the embodiment)

[0091] Hereinafter, the effects of the crosstalk measurement method according to the embodiment will be described.

[0092] When measuring the crosstalk between the signal pattern 12b and the signal pattern 13a, a high-frequency signal flows through the probes 32 and 33, so that crosstalk may occur between the probes 32 and 33. If crosstalk occurs between the probes 32 and 33, the crosstalk between the signal pattern 12b and the signal pattern 13a cannot be accurately measured.

[0093] The crosstalk measurement probe 20 has a shielding plate 40, which is arranged between the probe 32 and the probe 33 in the second direction DR2 and is in contact with the ground pattern 14a at the lower end 40b (that is, it is at the ground potential). Therefore, the electromagnetic waves emitted from the probes 32 and 33 are shielded by the shielding plate 40, and the crosstalk between the probes 32 and 33 is suppressed. In this way, according to the crosstalk measurement method involved in the embodiment, since the crosstalk measurement probe 20 is used, the measurement accuracy of the crosstalk between the signal pattern 12b and the signal pattern 13a is improved.

[0094] When the upper end 40a is located above the position P1, the electromagnetic waves emitted from the probes 32 and 33 are less likely to bypass the shielding plate 40. Therefore, in this case, the occurrence of crosstalk between the probes 32 and 33 and further crosstalk between the signal patterns 12b and 13a is further suppressed.

[0095] The larger the distance DIS is, the less likely it is that the electromagnetic waves emitted from the probes 32 and 33 will bypass the shielding plate 40, so it is easy to suppress the crosstalk between the probes 32 and 33. On the other hand, the larger the distance DIS is, the more the crosstalk between the signal pattern 12b and the signal pattern 13a, which should not be suppressed, is suppressed, and the measurement accuracy of the crosstalk between the signal pattern 12b and the signal pattern 13a is reduced. For this reason, by setting the distance DIS to be greater than 0.5 mm and less than 5 mm, the crosstalk between the signal pattern 12b and the signal pattern 13a can be more accurately measured.

[0096] When the shielding plate 40 has a plurality of protrusions 41 at the lower end 40b, it is easy to obtain contact between the shielding plate 40 and the ground pattern 14a. If the pitch P is too large or the height H is too large, the electromagnetic waves emitted from the probes 32 and 33 pass between two adjacent protrusions 41 and easily bypass the shielding plate 40. Therefore, when the pitch P is 0.4 mm or less and the height H is 0.5 mm or less, it is possible to easily obtain electrical contact between the shielding plate 40 and the ground pattern 14a while improving the measurement accuracy of the crosstalk. When the protrusions 41 have elasticity, it is possible to further easily obtain electrical contact with the ground pattern 14a.

[0097] The crosstalk measurement probe 20 has a spring component 51 and a spring component 52. When the shielding plate 40 is slidably clamped by the spring component 51 and the spring component 52, even if the length of the shielding plate 40 in the second direction DR2 is large, it is easy to obtain uniform electrical contact between the shielding plate 40 and the ground pattern 14a by sliding the shielding plate 40.

[0098] Fig.111 is a graph showing the relationship between the frequency of the differential signal flowing through the signal pattern 12 a and the signal pattern 12 b and the amount of crosstalk of the differential component to the signal pattern 13 a and the signal pattern 13 b . Fig.11 The horizontal axis in represents the frequency (unit: GHz) of the signal flowing through the signal pattern 12 a and the signal pattern 12 b . Fig.11 The vertical axis in is the crosstalk amount (unit: dB) of the differential component to the signal pattern 13a and the signal pattern 13b. Fig.11 As shown, sample 1, sample 2 and sample 3 are provided for crosstalk analysis.

[0099] For Sample 1 and Sample 2, the crosstalk between the signal pattern 12b and the signal pattern 13a was measured using the crosstalk measurement probe 20. For Sample 1, the shielding plate 40 did not have the plurality of protrusions 41 at the lower end 40b. On the other hand, for Sample 2, the shielding plate 40 had the plurality of protrusions 41 at the lower end 40b. For Sample 2, the pitch P was set to 0.4 mm, and the height H was set to 0.1 mm. For Sample 3, a crosstalk measurement probe without the shielding plate 40 was used.

[0100] For samples 1 and 2, the thickness T is set to 0.1 mm, and the shielding plate 40 is formed of copper. For samples 1 and 2, the height of the shielding plate 40 is set to 1.1 mm. For samples 1 and 2, the width of the shielding plate 40 in the second direction DR2 is set to 2.4 mm. For samples 1 and 2, the upper end 40a is located above the base end 30b of the measuring needle 32 and the measuring needle 33 in the third direction DR3, and the front end 40c and the rear end 40d are located at positions protruding from the position P2 and the position P3 in the second direction DR2, respectively. For samples 1 and 2, the distance DIS is set to 1.0 mm.

[0101] Regarding the printed wiring board 10 for crosstalk analysis, the base film 11 is formed of a fluororesin. Regarding the printed wiring board 10 for crosstalk analysis, the thickness of the base film 11 is set to 0.057 mm.

[0102] Regarding the printed wiring board 10 for crosstalk analysis, the thickness of the signal pattern 12a, the signal pattern 12b, the signal pattern 13a, the signal pattern 13b, the ground pattern 14a, the ground pattern 14b, the ground pattern 14c, and the ground pattern 15 is set to 0.012 mm. Regarding the printed wiring board 10 for crosstalk analysis, the signal pattern 12a, the signal pattern 12b, the signal pattern 13a, the signal pattern 13b, the ground pattern 14a, the ground pattern 14b, the ground pattern 14c, and the ground pattern 15 are formed of copper.

[0103] Regarding the printed wiring board for crosstalk analysis, the widths of the signal patterns 12a, 12b, 13a, and 13b in the first direction DR1 were set to 0.068 mm, and the width of the ground pattern 14a in the first direction DR1 was set to 0.368 mm. Regarding the printed wiring board 10 for crosstalk analysis, the intervals between the signal patterns 12a and 12b, the intervals between the signal patterns 13a and 13b, the intervals between the signal pattern 12b and the ground pattern 14a, and the intervals between the signal pattern 13a and the ground pattern 14a were set to 0.032 mm.

[0104] like Figure 8 As shown, for sample 3, since the crosstalk between the probe 32 and the probe 33 is large, only the crosstalk between the signal pattern 12b and the signal pattern 13a can be measured to about -60 dB. On the other hand, for samples 1 and 2, larger crosstalk can be measured. Therefore, it can be clearly seen from the simulation that the measurement accuracy of the crosstalk between the signal pattern 12b and the signal pattern 13a is improved according to the crosstalk measurement method involved in the embodiment.

[0105] The curve representing the results of the crosstalk analysis of sample 2 is substantially overlapped with the curve representing the results of the crosstalk analysis of sample 1. As can be seen from the simulation, by setting the pitch P to be less than 0.4 mm and the height H to be less than 0.5 mm, respectively, it is possible to easily obtain electrical contact between the shielding plate 40 and the ground pattern 14a while improving the measurement accuracy of the crosstalk.

[0106] The embodiments disclosed this time should be considered to be illustrative in all aspects and not restrictive. The scope of the present invention is indicated by the claims rather than the embodiments described above, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0107] Description of Reference Numerals

[0108] 10 printed wiring board; 11 base film; 11a first surface; 11b second surface; 11c through hole;

[0109] 12a, 12b, 13a, 13b signal patterns; 14a, 14b, 14c, 15 ground patterns; 16, 17, 18 conductor layers; 20 crosstalk measurement probes; 30, 31, 32, 33, 34, 36, 37, 38 probes; 30a top end; 30b base end; 40 shielding plate; 40a upper end; 40b lower end; 40c front end; 40d rear end; 41 protrusion; 51, 52 spring components; DIS distance; DR1 first direction; DR2 second direction; DR3 third direction; H height; P1, P2, P3 positions; S1 preparation process; S2 crosstalk measurement process; S11 first process; S12 second process; P pitch; T thickness.

Claims

1. A crosstalk measurement method, comprising: A step of preparing a printed wiring board, the printed wiring board having a first signal pattern, a second signal pattern, and a ground pattern, the first signal pattern and the second signal pattern being arranged at intervals in a first direction and extending in a second direction orthogonal to the first direction, the ground pattern being arranged between the first signal pattern and the second signal pattern in the first direction and extending in the second direction; A step of preparing a probe having a first probe needle, a second probe needle, and a shielding plate formed of a conductive material; as well as The step of measuring crosstalk between the first signal pattern and the second signal pattern, wherein the first probe and the second probe each have a tip and a base end, and the base end is an end on the side opposite to the tip. The tip of the first probe and the tip of the second probe are in contact with the first signal pattern and the second signal pattern, respectively. The shield plate extends along a plane perpendicular to the first direction and has an upper end and a lower end in a third direction perpendicular to the first direction and the second direction, wherein the lower end is an end opposite to the upper end and contacts the ground pattern. The shielding plate is located between the first measuring needle and the second measuring needle in the first direction, The thickness of the shielding plate is greater than the skin depth corresponding to the electromagnetic wave having a frequency equal to the signals flowing in the first signal pattern and the second signal pattern.

2. The crosstalk measurement method according to claim 1, wherein: The upper end is located above the base end of the first stylus and the base end of the second stylus in the third direction.

3. The crosstalk measurement method according to claim 1 or 2, wherein: The shielding plate has a rear end and a front end in the second direction, the front end being an end on a side opposite to the rear end, The front end is located at a position that protrudes from the front end of the first stylus and the front end of the second stylus by 0.5 mm or more and 5 mm or less in the second direction.

4. The crosstalk measurement method according to claim 3, wherein: The shield plate has a plurality of protrusions at the lower end thereof which are arranged at intervals along the second direction and contact the ground pattern. A pitch between two adjacent protrusions among the plurality of protrusions is 0.4 mm or less.

5. The crosstalk measurement method according to claim 4, wherein: The height of each of the plurality of protrusions is 0.5 mm or less.

6. A crosstalk measurement probe, comprising a first probe, a second probe, and a shielding plate formed of a conductive material, The first measuring needle and the second measuring needle each have a top end and a base end, and the base end is an end on the side opposite to the top end. The tip of the first probe and the tip of the second probe are arranged at intervals in a first direction, The shielding plate extends along a plane perpendicular to the first direction and is located between the first measuring needle and the second measuring needle in the first direction. The thickness of the shielding plate is greater than the skin depth corresponding to the electromagnetic wave having a frequency equal to the signal flowing in the first probe and the second probe.

7. The crosstalk measurement probe according to claim 6, wherein: The shielding plate has a rear end and a front end in a second direction orthogonal to the first direction, the front end being an end on a side opposite to the rear end, The front end is located at a position that protrudes from the front end of the first stylus and the front end of the second stylus by 0.5 mm or more and 5 mm or less in the second direction.

8. The crosstalk measurement probe according to claim 7, wherein: The shield plate has an upper end and a lower end in a third direction orthogonal to the first direction and the second direction, and has a plurality of protrusions arranged at intervals along the second direction at the lower end, the lower end being an end opposite to the upper end.

9. The crosstalk measurement probe according to claim 8, wherein: A pitch between two adjacent protrusions among the plurality of protrusions is 0.4 mm or less.

10. The crosstalk measurement probe according to claim 8 or 9, wherein: The height of each of the plurality of protrusions is 0.5 mm or less.

11. The crosstalk measurement probe according to claim 6 or 7, wherein: The shielding plate has an upper end and a lower end in a third direction orthogonal to the first direction and the second direction, wherein the lower end is an end on a side opposite to the upper end. The upper end is located above the base end of the first stylus and the base end of the second stylus in the third direction.

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