Probe for measuring magnetic permeability and magnetic permeability measuring device using same

Abstract

The invention provides a probe for measuring magnetic permeability, which can measure the magnetic permeability of a magnetic body, especially the imaginary number part of the complex magnetic permeability with high precision. A probe for measuring the magnetic permeability of a magnetic body is provided with: a transmission line body having a strip-shaped conductor formed on the front surface of a dielectric substrate and a ground conductor formed on the front surface or the back surface of the dielectric substrate; a first connector connected to one end of each of the bar-shaped conductor and the ground conductor; and a second connector connected to the other end of each of the bar-shaped conductor and the ground conductor, the bar-shaped conductor has a first length portion including a portion connected to the first connector at one end side, a second length portion including a portion connected to the second connector at the other end, and a third length portion extending between the first length portion and the second length portion. The third length portion has a current bias suppression unit.

Description

Technical Field

[0001] The present invention relates to a probe for measuring the magnetic permeability of a magnetic body and a magnetic permeability measuring device using the probe. Background Art

[0002] Currently, high-frequency applications using GHz bands such as mobile phones and wireless communications are becoming more popular. In addition, there is an urgent need for high-frequency magnetic materials that are useful for further miniaturization and high integration of these components. In particular, magnetic films with high magnetic permeability are also required for magnetic materials used in circuits. At the same time, the establishment of an evaluation method for high-frequency magnetic permeability is necessary.

[0003] The inventors of the present application have developed a magnetic permeability measuring device that does not require the processing of samples. Patent documents 1 to 4 disclose probes and magnetic permeability measuring devices developed by the inventors of the present application for measuring the magnetic permeability of magnetic bodies, especially film-shaped magnetic bodies. In the structure of the probe, a dielectric layer is sandwiched between a strip conductor that carries a high-frequency carrier signal and a ground conductor, so that the magnetic body to be measured is in contact with the conductor, and the transmission coefficient S of the magnetic body to be measured is measured. 21 , from which the magnetic permeability of the magnetic body can be calculated.

[0004] The magnetic permeability obtained is the complex magnetic permeability μ represented by the following formula (1), where μ' is the real part of the complex magnetic permeability μ and μ" is the imaginary part of the complex magnetic permeability μ.

[0005] [Number 1]

[0006] μ='-jμ"(1)

[0007] The real part μ' of the complex magnetic permeability μ corresponds to the inductance component L of the magnetic body, and the imaginary part μ" of the complex magnetic permeability μ corresponds to the loss amount (resistance component) of the magnetic body.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Publication No. 2010-060367

[0011] Patent Document 2: Japanese Patent Application Publication No. 2012-032165

[0012] Patent Document 3: Japanese Patent Application Publication No. 2015-172497

[0013] Patent Document 4: Japanese Patent Application Publication No. 2016-053569 Summary of the invention

[0014] Problems to be solved by the invention

[0015] Fig.17 The figure schematically shows the magnetic field region for exciting a magnetic body to be measured, especially a magnetic body having an area larger than the width of a strip conductor. The magnetic body 1 to be measured is excited by a high-frequency carrier signal (current) flowing in the strip conductor 2 of the probe in contact with it. According to the electromagnetic field analysis of the inventor of the present application, it is clear that when the strip conductor 2 is relatively thin and the width of the strip conductor 2 is relatively small relative to the width of the magnetic body 1, the entire magnetic body 1 is not excited but only a local area near the area in contact with the strip conductor 2 is excited, thereby causing a measurement error of the magnetic permeability.

[0016] When a magnetic body is locally excited, a reverse magnetic field is generated outside the locally generated magnetic field inside the magnetic body. Therefore, due to the influence of the reverse magnetic field, a magnetic flux that cancels the excited magnetic field is generated, thereby causing an error in the actual magnetic permeability of the magnetic body to be measured. More specifically, the resonance frequency in the imaginary part μ" of the complex magnetic permeability μ in the above formula (1) is offset, and sometimes the magnetic permeability cannot be measured with high accuracy. Fig.18 This is a graph showing a measurement example in which an error is generated in the imaginary part of the magnetic permeability due to the influence of the diamagnetic field. The graph shows the measurement values ​​obtained by using a probe with a microstrip line having a slender conductor and the measurement values ​​based on the standard magnetic permeability measurement method without the influence of the diamagnetic field, namely the Nicolson-Ross-Weir (NRW) method. Fig.18 (a) represents the value of the imaginary part μ" of the complex permeability μ, Fig.18 (b) represents the value of the real part μ' of the complex magnetic permeability μ. The magnetic material to be measured is a NiZn ferrite film (3mm×1mm×thickness 100μm). Fig.18 As shown in (a), the resonant frequency in the imaginary part μ" of the complex permeability μ shifts toward the high frequency side at 7 GHz relative to the measured value based on the NRW method, resulting in a large error in the measured value. It should be noted that Fig.18 The measured value of the real part μ' of the complex magnetic permeability μ shown in (b) is approximately the same as the measured value obtained by the NRW method, but the change point should have shifted to the high frequency side in the same manner. It may be difficult to observe because it is buried in noise.

[0017] The permeability evaluation of film-shaped magnetic materials as the sample to be measured is often measured using the NRW method, which is a standard measurement method, but the sample needs to be precisely processed into a ring shape and needs to be set on a coaxial tube with precise position accuracy, which is technically difficult and labor-intensive. On the other hand, when evaluating a signal transmission line such as a microstrip line with a strip conductor, as described above, when measuring a magnetic material with a larger area than the width of the strip conductor, the local magnetic field is strong due to the reverse magnetic field of the magnetic material, causing a shift in the ferromagnetic resonance frequency and a decrease in the permeability, making it difficult to accurately measure the material's inherent permeability.

[0018] The inventors of the present application have tried to increase the width of the strip conductor, increase the distance between the strip conductor and the sample, etc., but all attempts have failed. In particular, when the width of the strip conductor is increased, the current is biased toward the conductor width direction (periphery) due to the skin effect, making it impossible to measure smoothly.

[0019] Therefore, an object of the present invention is to provide a magnetic permeability measuring probe capable of measuring the magnetic permeability of a magnetic body having an area larger than the width of a strip conductor with high accuracy, and a magnetic permeability measuring device using the probe.

[0020] Solutions for solving problems

[0021] The magnetic permeability measuring probe of the present invention for achieving the above-mentioned purpose is a probe for measuring the magnetic permeability of a magnetic body, characterized in that it comprises: a transmission line body having a strip conductor in the form of a band formed on the front surface of a dielectric substrate and a ground conductor formed on the front surface or the back surface of the dielectric substrate; a first connector connected to one end of each of the strip conductor and the ground conductor; and a second connector connected to the other end of each of the strip conductor and the ground conductor, wherein the strip conductor comprises: a first length portion including a portion connected to the first connector at one end, a second length portion including a portion connected to the second connector at the other end, and a third length portion extending between the first length portion and the second length portion, wherein the third length portion has a current bias suppression unit.

[0022] Effects of the Invention

[0023] According to the present invention, by setting a current bias suppression unit in the strip conductor of the transmission line body, the bias of the current in the conductor width direction caused by the skin effect can be suppressed, and the influence of the reverse magnetic field can be reduced, thereby enabling the magnetic permeability of the magnetic body (especially the imaginary part of the complex magnetic permeability) to be measured with high precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a diagram showing a schematic configuration example of a magnetic permeability measurement device according to an embodiment of the present invention.

[0025] Figure 2 It is a diagram showing a first configuration example of a probe in the first embodiment of the present invention.

[0026] Figure 3 It is a diagram showing the pattern of the strip conductors constituting the probe.

[0027] Figure 4 The diagram schematically shows a magnetic field region in which a magnetic substance 1 to be measured is excited by a wide strip conductor 11 provided with slits 17 in the first embodiment of the present invention.

[0028] Figure 5 It is a diagram showing a modified example of the pattern of the strip conductor in the probe.

[0029] Figure 6 It is a diagram showing a second configuration example of the probe in the first embodiment of the present invention.

[0030] Figure 7 It is a diagram showing a strip conductor according to a second embodiment of the present invention.

[0031] Figure 8 It is a diagram showing a strip conductor according to a third embodiment of the present invention.

[0032] Fig. 9 It is a diagram showing a strip conductor according to a fourth embodiment of the present invention.

[0033] Fig.10 It is a diagram showing a strip conductor according to a fifth embodiment of the present invention.

[0034] Fig.11 Detailed Description of the Invention This is a flowchart showing the steps of a magnetic permeability measurement method according to an embodiment of the present invention.

[0035] Fig.12 The figure schematically shows the shape of a magnetic thin film of a magnetic body to be measured.

[0036] Fig.13 This is a graph showing the results of magnetic permeability measurement obtained by a magnetic permeability measurement device using the probe according to the embodiment of the present invention.

[0037] Fig.14 It is a diagram showing a modification of the strip conductor 11 constituting the probe pin according to the first embodiment of the present invention.

[0038] Fig.15 This is a diagram showing another modified example of the strip conductor 11 constituting the probe pin according to the first embodiment of the present invention.

[0039] Fig.16It is a graph showing the measurement results of the current density flowing through the strip conductor 11 .

[0040] Fig.17 The figure schematically shows the magnetic field region for exciting a magnetic body to be measured when a conventional probe is used.

[0041] Fig.18 This is a graph showing a measurement example in which an error occurs in the imaginary part of the magnetic permeability due to the influence of the reverse magnetic field. DETAILED DESCRIPTION

[0042] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, this embodiment example does not limit the technical scope of the present invention.

[0043] Figure 1 1 is a diagram showing a schematic configuration example of a magnetic permeability measuring device according to an embodiment of the present invention. The magnetic permeability measuring device according to an embodiment of the present invention is configured to include a probe 10, a network analyzer (signal measuring device) 20, and an operation processing device (for example, a computer device such as a personal computer) 30 (processing unit) that performs numerical analysis processing.

[0044] The magnetic substance 1 to be measured is, for example, a film-shaped magnetic substance with a thickness of about 100 μm. The probe 10 is arranged in contact with or close to the magnetic substance 1 and is connected to the network analyzer 20 via the non-magnetic coaxial cable 3. The transmission coefficient S of the magnetic substance 1 to be measured is measured by the network analyzer 20. 21 The signal data is input to the control personal computer 30, and the complex magnetic permeability of the magnetic body is obtained by a predetermined numerical analysis process (such as optimization process). In addition, in order to magnetically saturate the magnetic body 1, a magnet (magnetic field applying unit) composed of a double yoke type electromagnet 40 is used.

[0045] Figure 2 is a diagram showing a first configuration example of a probe in a first embodiment of the present invention, Figure 3 It is a diagram showing the pattern of the strip conductors constituting the probe.

[0046] The probe 10 is configured to include: a transmission line body 14, which is a microstrip line and has a structure in which a dielectric substrate 13 is sandwiched between a strip conductor 11 and a ground conductor 12; and connectors 15 and 16, which are electrically connected to both ends of the transmission line body 14 in the longitudinal direction. The transmission line body 14 is configured to include a dielectric substrate 13, a strip-shaped strip conductor 11 formed on the front surface thereof, and a ground conductor 12 formed on the back surface of the dielectric substrate 13. The connectors 15 and 16 are connected to a 50Ω coaxial cable 3 and are connected to a network analyzer 20. The transmission line body 14 is made by etching a printed substrate made of fluororesin (for example, polytetrafluoroethylene (PTFE)), for example.

[0047] The strip conductor 11 includes a first length portion 11a including a portion connected to the connector 15 at one end thereof in the length direction, a second length portion 11b including a portion connected to the connector 16 at the other end thereof in the length direction, and a third length portion 11c extending between the first length portion 11a and the second length portion 11b, the third length portion 11c having at least one slit 17 extending in the length direction.

[0048] The strip conductor 11 is formed to be relatively wide (e.g., 1.2 mm wide) in accordance with the width direction length of the magnetic body 1 to be measured, and is designed to have a size greater than the width direction length of the magnetic body 1 to be measured. By forming the strip conductor 11 to be relatively wide, the entire front surface of the magnetic body 1 to be measured can be brought into contact with the third length portion 11 c of the strip conductor 11.

[0049] On the other hand, when the strip conductor 11 is designed to be wider, it is clear that most of the high-frequency carrier signal (current) flowing in the strip conductor 11 flows in the two end regions (left and right ends) in the width direction of the strip conductor 11, and almost does not flow in the central part therebetween. Therefore, in the present invention, in order to make the high-frequency carrier signal (current) flow roughly evenly in the entire width direction of the wide strip conductor 11, a slit 17 is provided as a current bias suppression unit.

[0050] The slit 17 is an elongated gap region extending in the region of the third length portion 11c along the length direction of the strip conductor 11. By providing the slit 17, in the region of the third length portion 11c of the strip conductor 11, a wide strip conductor portion is divided into a plurality of elongated strip conductor portions 18 extending in parallel, so that current can flow evenly through the elongated strip conductor portions 18 divided by the slit 17. The plurality of slits 17 are preferably formed so as to extend in parallel with each other in the length direction.

[0051] Taking into account the skin effect of the conductor under high-frequency current, the width dimension h of each elongated strip conductor portion 18 that enables a uniform current to flow therethrough is determined based on the skin depth representing the skin effect of the strip conductor 11 (the skin depth can also be determined by approximate calculation). The width dimension s and the number of slits 17 are determined by the relationship between the width dimension w of the third length portion 11c and the width dimension h of the elongated strip conductor portion 18. Within the scope of manufacturing technology, by making the width dimension s of the slit 17 shorter, forming a larger number of slits 17, and forming a larger number of elongated strip conductor portions 18, the current distribution in the width direction can be made more uniform in the region of the third length portion 11c of the strip conductor 11.

[0052] The width s of the slit 17 and the width h of the elongated strip conductor portion 18 of the present invention are preferably about 0.1 μm to 100 μm, and more preferably 1 μm to 10 μm. The width of the slit 17 and the width of the elongated strip conductor portion 18 can be the same, or different as described later. The smaller the slit width, the higher the uniformity of the current and excitation can be even in the high frequency band. The manufacturing method includes well-known methods such as sputtering, electrolysis (electrodeposition), etc.

[0053] exist Figure 2 and Figure 3 In the pattern of the strip conductor 11 shown, the width dimension s of the slits 17 is the same and the arrangement intervals thereof are also arranged at equal intervals, and the width dimension h of the elongated strip conductor portions 18 is also the same and the arrangement intervals thereof are also equal. The width dimension h of the elongated strip conductor portions 18 is equivalent to the interval dimension of the slits 17, and the width s of the slits 17 is equivalent to the interval dimension of the elongated strip conductors 18.

[0054] Figure 4 The figure schematically shows the magnetic field region in which the wide strip conductor 11 provided with the slit 17 in the first embodiment of the present invention excites the magnetic body 1 to be measured. By forming the strip conductor 11 (the third length portion 11c in contact with the magnetic body 1) to be wide in a manner corresponding to the size of the magnetic body 1 to be measured and providing the above-mentioned slit 17, the bias of the current in the conductor width direction caused by the skin effect is suppressed, and a uniform current flows through the entire strip conductor 11 (the third length portion 11c in contact with the magnetic body 1), so that the magnetic body 1 to be measured is not locally excited but is excited as a whole. As a result, even if the magnetic body 1 to be measured has a large area, the influence of the diamagnetic field can be reduced, and the magnetic permeability of the magnetic body to be measured can be measured with high accuracy.

[0055] Figure 5 1 is a schematic diagram showing a modified example of the pattern of the strip conductor 11 in the probe. Figure 5 In the example shown in (a), the width of the first length portion 11a and the second length portion 11b of the strip conductor 11 is smaller than that of the third length portion 11c, and the width of the first length portion 11a and the second length portion 11b only needs to be able to connect to the connectors 15 and 16 respectively. The third length portion 11c tapers on both sides and is reduced to the width of the first length portion 11a and the second length portion 11b. Figure 5In (a), a pattern is shown in which the width dimension of the third length portion 11c tapers, but even a pattern that bends at a right angle and tapers can be smoothly connected by a curve. In addition, the third length portion 11c only needs to have a larger width dimension than the first length portion 11a and the second length portion 11b, and the entire length can be circular.

[0056] Figure 5 The example shown in (b) shows a pattern in which the arrangement intervals of the slits 17 are different from each other in the width direction. Specifically, the slits 17 are arranged at different intervals from each other in such a manner that the slender strip conductor parts 18 are arranged more sparsely from both ends to the center in the width direction. In this case, the width dimension h of the slender strip conductor parts 18 increases from both ends to the center. The width dimension s of each slit 17 is the same.

[0057] As described above, in a wide conductor, a larger current flows at both ends in the width direction, and a smaller current flows near the center. Therefore, according to the current distribution, in order to make a larger current flow near the center, the elongated strip conductor portion 18 is sparser in the center than on both ends, and the width dimension h of the elongated strip conductor portion 18 is smaller on both ends and larger as it approaches the center. In this way, the bias of the current distribution can be corrected to form a more uniform current distribution.

[0058] According to the simulation analysis of the inventors of the present application, it is clear that the current distribution decreases exponentially from the two ends of the wide conductor to the center, specifically, it decreases by 1 / e (natural logarithm). Therefore, the width dimension h of the plurality of elongated strip conductor portions 18 separated by the slits 17 is preferably set to increase the width from the two ends to the center, for example, by a multiple of the natural logarithm e. The multiple value can be a value close to 2 to 3 times the natural logarithm e.

[0059] Figure 5 The example shown in (c) shows a pattern in which the width dimension s of the slit 17 is different in the width direction. Figure 5 (b) Similarly, in order to arrange the elongated strip conductor parts 18 more sparsely as they are arranged from both ends to the center in the width direction, the plurality of slits 17 are arranged with different width dimensions s. In this case, the width dimension s of the slit 17 increases as it is closer to the center from both ends. The width dimension h of each elongated strip conductor part 18 is the same.

[0060] exist Figure 5 In the example of (c) of FIG. 1 , by arranging the elongated strip-shaped conductor portions 18 in a manner that the number of portions is sparser in the center than in the two end portions, the bias in the current distribution can be corrected, thereby forming a more uniform current distribution.

[0061] Alternatively, the slits 17 may have different widths s and different arrangement intervals (corresponding to the width h of the elongated strip conductor portions 18 ).

[0062] The pattern of the slits 17 is not limited to the rectangular shape as described above, but may be any shape such as an elongated ellipse. Any shape is acceptable as long as the current does not deflect to both ends of the conductor in the width direction to form a large current.

[0063] Figure 6 1 is a diagram showing a second configuration example of a probe in an embodiment of the present invention. The probe 10 in the second configuration example has a transmission line body 14 that forms a coplanar line, and has a structure including a strip conductor 11 formed on the front surface of a dielectric substrate 13 and two ground conductors 12 spaced apart and arranged on both sides of the strip conductor 11 on the same surface. The probe 10 is configured to include a transmission line body 14 that forms the coplanar line and connectors 15 and 16 that are electrically connected to both ends of the transmission line body 14 in the longitudinal direction. The pattern of the strip conductor 11 of the transmission line body 14 can be applied to the same Figure 3 or Figure 5 The transmission line body 14 is not limited to the microstrip line and coplanar line shown as examples, and may be other transmission line structures.

[0064] Next, a configuration example of a probe in a second embodiment of the present invention is shown. Figure 7 It is a diagram showing a pattern of strip conductors constituting a probe according to a second embodiment of the present invention.

[0065] The difference from the probe 10 of the first embodiment is that the third length portion of the strip conductor 11 is formed of conductors made of a plurality of materials having different resistance values ​​as the current bias suppressing means instead of or in addition to the slit 17 .

[0066] At this time, in order to prevent the current from being deflected to the two ends of the conductor in the width direction and generating a large current, the two ends in the width direction are made of a conductor 11-1 made of a material with a high resistance value, and the central part is made of a conductor 11-2 made of a material with a low resistance value. The conductor can be made of two or more materials, and one of the materials can be the same as that used in the first length portion and the second length portion. Figure 7 The example shown is an example in which the conductors are made of three materials, and a conductor 11-3 made of a material having an intermediate resistance value is arranged between the conductor 11-1 made of a material having a high resistance value and the conductor 11-2 made of a material having a low resistance value.

[0067] In addition, the strip conductors made of different materials may be in close contact with each other, or may be separated by slits as in the first embodiment.

[0068] By using conductors made of a plurality of materials having different resistance values, the current does not flow in a biased manner at both ends of the wide portion of the strip conductor in the width direction to generate a large current, so that even a sample having a large area can be measured with high accuracy.

[0069] Next, a configuration example of a probe in a third embodiment of the present invention is shown. Figure 8 It is a diagram showing a pattern of strip conductors constituting a probe according to a third embodiment of the present invention.

[0070] The difference from the probe 10 in the first embodiment is that, in the third length portion of the strip conductor 11, a conductor 11-4 having a higher conductivity than the strip conductor is stacked on the center portion of the strip conductor as a current bias suppressing unit instead of or in addition to the slit 17.

[0071] like Figure 8 As shown in FIG. 1 , when the conductor 11-4 with high conductivity is stacked on the strip conductor, it is preferable to form the upper surface of the stacked strip conductor to be flat. (The original strip conductor is formed to be thin in the middle. Or, after the strip conductor is formed, the middle part is removed.) This is because the magnetic body 1 to be measured is often a plane. In this case, if the upper surface of the strip conductor is not horizontal, it is difficult to place the measured object horizontally. However, depending on the sample to be measured, it can also be directly stacked on the strip conductor.

[0072] A conductor 11 - 4 having a higher conductivity than the strip conductor is provided in the center portion of the strip conductor, so that the current does not deflect to both ends in the width direction of the conductor to generate a large current.

[0073] The conductor 11 - 4 with high conductivity may be stacked with a plurality of conductors with higher conductivity toward the center.

[0074] Here, an example is described in which the conductor 11 - 4 having a higher conductivity than the strip conductor 11 is applied to the center portion of the strip conductor 11 , but the same effect can be obtained by providing conductors having a lower conductivity than the strip conductor at both ends of the strip conductor 11 in the width direction.

[0075] The method of providing the conductor 11 - 4 with high conductivity may be any method as long as it is a known method, and a method of applying silver paste, a method of forming by sputtering, or a method of depositing by electrolysis may be used.

[0076] Thus, by providing conductors having different conductivities on the strip conductor, a large current will not flow toward both ends in the width direction of the wide portion of the strip conductor, so that even a sample having a large area can be measured with high accuracy.

[0077] Next, a configuration example of a probe in a fourth embodiment of the present invention is shown. Fig. 9 It is a diagram showing a pattern of strip conductors constituting a probe according to a fourth embodiment of the present invention.

[0078] The difference from the probe 10 of the first embodiment is that in the third length portion of the strip conductor 11, instead of or in addition to the slit 17, the film thickness of the central portion of the strip conductor is increased as a current bias suppression unit, and the film thickness decreases toward both ends in the width direction. Fig. 9 (a) shows a structural example in which the film thickness of the strip conductor is different without providing the slit 17. Fig. 9 (b) shows a structural example in which the slits 17 are provided to make the film thickness of the strip conductor different.

[0079] like Fig. 9 As shown in (a) and (b), in order to make the upper surface of the strip conductor flat when the film thickness is increased, it is preferred to form grooves of different depths in the dielectric substrate 13 and embed the strip conductor therein. This is because the magnetic body 1 to be measured is often a plane, and in this case, if the upper surface of the strip conductor is not horizontal, it is difficult to place the measurement object horizontally. However, depending on the sample to be measured, the film thickness may be increased on the planar dielectric substrate 13.

[0080] The film thickness of the strip conductor is larger in the center and becomes thinner toward both ends in the width direction, so current easily flows to the center portion with lower resistance, and the current does not deflect to the two ends in the width direction of the conductor to form a large current.

[0081] like Fig. 9 As shown in (b), it is more effective to combine a structure in which the film thickness of the central portion of the strip conductor is larger than that of both ends with a structure in which the slit 17 is provided.

[0082] Thus, by providing conductors having different conductivities on the strip conductor, a large current will not flow toward both ends in the width direction of the wide portion of the strip conductor, so that even a sample having a large area can be measured with high accuracy.

[0083] Next, a configuration example of a probe in a fifth embodiment of the present invention is shown. Fig.10 It is a diagram showing a pattern of strip conductors constituting a probe according to a fifth embodiment of the present invention.

[0084] The difference from the probe 10 in the first embodiment is that the third length portion of the strip conductor 11 is doped with a substance 11 - 5 that increases the conductivity of the central portion as a current bias suppressing unit so that the conductivity of the central portion of the strip conductor 11 becomes higher.

[0085] Since the central portion of the strip conductor 11 has high conductivity, current easily flows to the central portion where resistance is low, and thus the current does not deflect to both ends in the width direction of the conductor to generate a large current.

[0086] The same effect can be obtained by doping a substance 11 - 5 that reduces the conductivity near both ends of the conductor in the width direction to increase the resistance at both ends in the width direction.

[0087] By performing various doping on the strip conductor in this manner, a large current will not flow toward both ends in the width direction of the wide portion of the strip conductor, and thus even a sample having a large area can be measured with high accuracy.

[0088] The embodiments of the present invention are not limited to those described above, and any configuration may be used as long as more current can flow to the central portion.

[0089] The following describes a measurement procedure of a magnetic permeability measurement device including the probe 10 of the present invention described above.

[0090] Fig.11 Flow chart showing the steps of the magnetic permeability measurement method in an embodiment of the present invention. The transmission line body 14 of the probe 10 is brought into contact with the magnetic body 1 of the measurement object (S100). Then, it enters the magnetic pole gap of the double yoke electromagnet 40, applies a strong DC magnetic field (for example, about 20kOe), saturates the magnetic body 1, and performs calibration through the network analyzer 20 (S102). Thus, the electrical length of the probe 10 and the coaxial cable 3, the DC impedance of the magnetic body, the non-magnetic signal, etc. are removed. After that, the DC magnetic field is released, and the transmission coefficient S of the contribution of the magnetic body 1 is measured. 21 (S104). According to the following formula (2), the transmission coefficient S 21 It is converted into the impedance Z of the magnetic body 1 (S106).

[0091] [Number 2]

[0092]

[0093] Specifically, the transmission coefficient S 1 is measured by the network analyzer 20 when a magnetic field for saturating the magnetic body 1 is applied and when a magnetic field is not applied. 21. Probe 10 is brought into contact with magnetic substance 1, and the transmission coefficient at this time is used as the reference signal when the magnetic substance 1 is saturated by an electromagnet. Next, the transmission coefficient is measured when the magnetic field of the electromagnet is removed. The transmission coefficient at this time is a differential signal with the reference signal, that is, the difference between the transmission coefficients when a magnetic field is applied and when no magnetic field is applied, which reflects the magnetic properties of magnetic substance 1. The difference in the transmission coefficient becomes the impedance component contributed by magnetic substance 1.

[0094] According to formula (2), impedance Z is the difference value of transmission coefficient, the real part is the loss amount (resistance component) R of magnetic body 1, and the imaginary part is the inductance component L of magnetic body 1. The inductance component L corresponds to the real part μ' of the magnetic permeability of magnetic body 1, and the resistance component R corresponds to the imaginary part μ" of the magnetic permeability of magnetic body 1. In addition, the magnetic permeability (complex magnetic permeability) μ of magnetic body 1 is expressed by the following formula (3). In addition, formula (3) is the same as formula (1) of the above-mentioned background technology item.

[0095] [Number 3]

[0096] ='-jμ"(3)

[0097] Fig.12 : is a diagram schematically showing the shape of the magnetic thin film of the magnetic body to be measured. As the frequency of the current flowing through the strip conductor 11 increases, the current flows only on the surface of the magnetic body (magnetic thin film) 1 due to the skin effect. Fig.12 As shown, it is assumed that the impedance Z is determined by the current biased in the film thickness direction due to the skin effect. As a numerical analysis process, for example, the above formula (3) and the following formulas (4) and (5) are used, and the Newton-Raphson method is used to repeatedly calculate μ' and μ", and the complex magnetic permeability is obtained through optimization processing so that the specified evaluation function value is minimized (S108).

[0098] [Number 4]

[0099]

[0100] [Number 5]

[0101]

[0102] Where Z is impedance, ρ is resistivity, l is sample length, w is sample width, t is film thickness, f is frequency, and μ is complex permeability.

[0103] Fig.13This is a graph showing the results of magnetic permeability measurement using a magnetic permeability measuring device using a probe according to an embodiment of the present invention. The sample to be measured is a NiZn ferrite thin film (3 mm × 1 mm × thickness 100 μm), and the results are compared with the values ​​measured by the NRW method, which is a standard magnetic permeability measurement method without the influence of a reverse magnetic field. The transmission line body 14 provided with the slit 17 is used Figure 2 The measured value of the magnetic permeability measured by the probe in the embodiment of the present invention roughly corresponds to the measured value based on the NRW method, and the influence of the reverse magnetic field can be suppressed. In the entire frequency band up to the high frequency band, the real part μ' and the imaginary part μ" of the complex magnetic permeability (μ=μ'-jμ") can be measured with high precision.

[0104] Fig.14 It is a diagram showing a modification of the strip conductor 11 constituting the probe pin according to the first embodiment of the present invention. Fig.14 (a) indicates that Figure 5 (a) The same pattern of the strip conductor 11, Fig.14 (b) is Fig.14 An enlarged view of portion A surrounded by a dotted line in (a). Fig.14 The third length portion 11c of the strip conductor 11 shown has a larger width dimension in the width direction than the first length portion 11a and the second length portion 11b, and a plurality of slits 17 are arranged in parallel in the entire width direction of the third length portion 11c. Preferably, the plurality of slits 17 have the same length in the longitudinal direction.

[0105] The third length portion 11c is formed into a tapered shape in which the edge portion (width direction edge portion) 11e extending in the width direction thereof becomes thinner as it approaches the two ends in the width direction. Thus, the interval d extending in the length direction from the length direction end portion 17e of each slit to the width direction edge portion 11e of the third length portion 11c is designed to become smaller as it approaches the two ends from the center portion in the width direction.

[0106] More specifically, if Fig.14As shown in (b), with respect to the first slit 17-1 relatively located at the two end sides in the width direction and the second slit 17-2 located at the center side of the first slit 17-1 in the width direction, the first interval d1 extending in the length direction from the length direction end 17-1e of the first slit 17-1 to the width direction edge 11e of the third length portion 11c is designed to be shorter than the second interval d2 extending in the length direction from the length direction end 17-2e of the second slit 17-2 to the width direction edge 11e of the third length portion 11c. In the width direction of the strip conductor 11, the interval d is made smaller as it approaches the two end sides, so that the flow path of the current flowing in the strip conductor 11 becomes narrower as it approaches the two end sides, thereby increasing the resistance at the two end sides, suppressing the bias of the current flowing at the two end sides, and making the current flow more uniformly through the entire strip conductor 11.

[0107] The narrowest interval d (first interval d1) is preferably as short as possible, but is preferably about 2 μm to 10 μm, for example, due to restrictions on design and manufacturing accuracy of microfabrication technology.

[0108] Fig.15 This is a diagram showing another modified example of the strip conductor 11 constituting the probe pin according to the first embodiment of the present invention. Fig.15 (a) shows the pattern of the strip conductor 11, Fig.15 (b) is Fig.15 An enlarged view of the portion B surrounded by the dotted line in (a). Fig.15 The third length portion 11c of the strip conductor 11 shown has a larger width dimension in the width direction than the first length portion 11a and the second length portion 11b, and a plurality of slits 17 are arranged in parallel in the entire width direction of the third length portion 11c. The lengths of the plurality of slits 17 in the longitudinal direction are different, and are designed to be longer toward both ends in the width direction.

[0109] The third length portion 11c is formed in a shape in which its width direction edge portion 11e rises at right angles from the strip-shaped first length portion 11a and the second length portion 11b to both ends in the width direction, and the third length portion 11c is in a rectangular shape as a whole. Therefore, since the lengths of the plurality of slits 17 are different, the interval d extending along the length direction from the length direction end 17e of each slit to the width direction edge portion 11e of the third length portion 11c is designed to be smaller from the central portion in the width direction to the both ends, and the conductor width is smaller toward the end, thereby suppressing the skin effect on the end.

[0110] More specifically, in Fig.15 In (b), Fig.14(b) Similarly, with respect to the first slit 17-1 relatively located at the two end sides in the width direction and the second slit 17-2 located closer to the center side than the first slit 17-1 in the width direction, the first interval d1 extending in the length direction from the length direction end 17-1e of the first slit 17-1 to the width direction edge 11e of the third length portion 11c is designed to be shorter than the second interval d2 extending in the length direction from the length direction end 17-2e of the second slit 17-2 to the width direction edge 11e of the third length portion 11c. In the width direction of the strip conductor 11, the interval d is made smaller as it approaches the two end sides, so that the flow path of the current flowing in the strip conductor 11 becomes narrower as it approaches the two end sides, thereby increasing the resistance on the two end sides, suppressing the bias of the current flowing on the two end sides, and enabling the current to flow more evenly through the entire strip conductor 11. In addition, Fig.15 In the example shown, the position and width of the slits may be preferably adjusted so that the conductor width (the conductor width between the slits and the outermost conductor width) decreases from the center toward the end portions in order to prevent current from flowing toward the end portions.

[0111] in addition, Fig.14 , Fig.15 A variation of Figure 5 The configuration of the slits 17 shown in (b) is different in the center and at both ends, or Figure 5 The effect is further improved by combining the structure shown in (c) that makes the width dimension s of the slit 17 different in the width direction at the center and at both ends. In addition, it is not limited to the slit, Fig.14 , Fig.15 The modified example can also be compared with Fig. 9 The structure shown in (a) and (b) of the invention is to increase the film thickness in the center and to make it different in the center and at both ends, or Fig.10 The effect can be further enhanced by combining the structure shown in which the conductivity is different between the center and the two end sides.

[0112] Fig.16 is a diagram showing the measurement results of the current density flowing in the strip conductor 11, Fig.16 The current density at each position in the width direction of the three shape patterns of the third length portion 11c (shape of only the upper half) of the strip conductor 11 shown in (a), (b) and (c) is as follows: Fig.16 as shown in (d). Fig.16 The three shapes (a), (b) and (c) are common in that the length of the third length portion 11c is 1.2 mm, the length of the slit 17 is 1 mm, and the length in the width direction (upper half only) is 2 mm. Fig.16 (a) is a pattern in which no tapered portion is provided at the edge portion 11e in the width direction. Fig.16(b) is a pattern in which a tapered portion is formed at a position 1.6 mm higher than the widthwise edge 11e. Fig.16 (c) is a pattern in which a tapered portion is formed from a position where the rise is 0.8 mm. Fig.16 As shown in the graph (d), it is clear that the longer the tapered portion is set, that is, the shorter the interval d is from the central portion in the width direction to the two end sides, the smaller the current density at the end portions. As a result, the bias (concentration) of the current toward the ends in the width direction is suppressed, which is effective as a method to make the current density more uniform.

[0113] The present invention is not limited to the above-described embodiments, and includes various modifications and corrections that can be conceived by a person having ordinary knowledge in the field of the present invention, and design changes within the scope that do not depart from the gist are of course included in the present invention.

[0114] Explanation of symbols

[0115] 1: Magnetic body

[0116] 3: Coaxial cable

[0117] 10: Probe

[0118] 11: Strip conductor

[0119] 12: Grounding conductor

[0120] 13: Dielectric substrate

[0121] 14: Transmission line

[0122] 15: Connector

[0123] 16: Connector

[0124] 17: Slit (current bias suppression unit)

[0125] 18: Slim strip conductor part

[0126] 20: Network analyzer (signal measurer)

[0127] 30: Calculation and processing device

[0128] 40: Double yoke type electromagnet.

Claims

1. A probe, characterized in that: Used to measure the magnetic permeability of magnetic bodies, with: A transmission line body having a strip conductor in the form of a belt formed on the front surface of a dielectric substrate and a ground conductor formed on the front surface or the back surface of the dielectric substrate; A first connector connected to one end of each of the strip conductor and the ground conductor; as well as a second connector connected to the other ends of the strip conductor and the ground conductor, The strip conductor has a first length portion including a portion connected to the first connector at one end, a second length portion including a portion connected to the second connector at the other end, and a third length portion extending between the first length portion and the second length portion. The third length portion has a current bias suppression unit.

2. The probe according to claim 1, characterized in that The transmission line body is a microstrip line or a coplanar line.

3. The probe according to claim 1, characterized in that The current bias suppression unit is provided with at least one slit extending along the length direction of the strip conductor.

4. The probe according to claim 3, characterized in that: The slits are a plurality of slits extending parallel to each other in the longitudinal direction of the strip conductor.

5. The probe according to claim 4, characterized in that The plurality of slits are arranged at equal intervals from each other in the width direction.

6. The probe according to claim 4, characterized in that The plurality of slits are arranged at different intervals from each other in the width direction.

7. The probe according to claim 6, characterized in that: The plurality of slits are arranged such that the intervals therebetween increase from both end sides toward the center in the width direction.

8. The probe according to claim 7, characterized in that: The strip conductor is formed so that the film thickness at the center portion in the width direction is larger than the film thickness at both ends thereof.

9. The probe according to claim 4, characterized in that: The plurality of slits are formed to have the same width dimension as each other.

10. The probe according to claim 4, characterized in that: The plurality of slits are formed with different width sizes from each other.

11. The probe according to claim 10, characterized in that: The plurality of slits are arranged so that the width dimension increases from both ends toward the center in the width direction.

12. The probe according to claim 4, characterized in that: The third length portion has a dimension wider in the width direction than the first length portion and the second length portion, The plurality of slits include first slits located at both end sides relatively in the width direction and second slits located closer to the center side than the first slits in the width direction. A first interval extending from a longitudinal end of the first slit to a width edge of the third length portion in the longitudinal direction is shorter than a second interval extending from a longitudinal end of the second slit to a width edge of the third length portion in the longitudinal direction.

13. The probe according to claim 12, characterized in that: The first slit and the second slit have the same length, The widthwise edge of the third length portion is formed in a tapered shape, and the length dimension of the third length portion decreases from the center side in the widthwise direction toward both ends.

14. The probe according to claim 12, characterized in that: The length dimension of the third length portion is kept the same from the center side to both ends in the width direction. The length dimension of the first slit is larger than that of the second slit.

15. The probe according to claim 1, characterized in that The current bias suppressing unit is configured such that, in the width direction of the third length portion perpendicular to the length direction of the strip conductor, the resistance decreases from the end portion toward the inner side.

16. The probe according to claim 15, characterized in that The strip conductor in the current bias suppression unit is made of a plurality of materials with different resistances.

17. The probe according to claim 15, characterized in that The strip conductor in the current bias suppression unit is provided with a material having a conductivity different from that of the strip conductor.

18. The probe according to claim 15, characterized in that The strip conductor in the current bias suppressing unit has a film thickness greater at the inner side than at the end portion.

19. The probe according to claim 15, characterized in that The strip conductor in the current bias suppression unit is doped with a substance that changes conductivity.

20. A magnetic permeability measuring device, characterized in that: have: The probe according to any one of claims 1 to 19; A magnetic field applying unit, used for applying a magnetic field to the magnetic body; A signal measuring device connected to the probe via a cable, and used to measure the signal of the transmission coefficient when the magnetic field applying part applies a magnetic field and when the magnetic field is not applied; as well as A processing unit is configured to obtain the magnetic permeability of the magnetic body by numerical analysis calculation processing based on the signal of the transmission coefficient measured by the signal measuring device.

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