JP7251772B2 - Magnetic property measuring device and magnetic property measuring method - Google Patents

Description

The present invention relates to a magnetic property measuring device and a magnetic property measuring method.

In recent years, attention has been focused on next-generation semiconductor devices such as SiC (silicon carbide) and GaN (gallium nitride). For example, in the field of power electronics, if next-generation semiconductor devices (next-generation power semiconductors) are applied, switching speeds can be increased, and along with this, passive elements such as inductors and capacitors can be miniaturized. Since the miniaturization of such devices is directly linked to the increase in power density, for example, accurate evaluation of loss is essential for optimal passive element design.

For example, methods such as the Steinmetz method and the loss map method are used for loss evaluation in inductors. In these methods, for example, the loss (minor loop) is calculated using the DC bias component of the magnetic field and the ripple component of the magnetic flux density as parameters for each different frequency.

Therefore, for example, establishment of a method for accurately measuring magnetization curves at operating frequencies to which the above-described next-generation semiconductor devices are applied is required. For example, when developing a new magnetic material, it is necessary to accurately determine the magnetic properties (magnetization properties) of the magnetic material (measurement sample) at an operating frequency of several MHz or higher.

By the way, conventionally, various proposals have been made as magnetic property measurement techniques for measuring the magnetic property of a measurement sample.

JP 2018-173331 A JP-A-2000-208327

Y. Han, et al., "Evaluation of Magnetic Materials for Very High Frequency Power Applications," IEEE Power Electronics Specialists Conference, pp.4270-4276, June 2008

As mentioned above, various methods have been proposed for measuring the magnetic properties of a measurement sample. , BH loop tracer is used.

FIG. 1 is a diagram for explaining an example of a BH loop tracer. In FIG. 1, reference numeral 5 is a ring-shaped measurement sample, 61 is a primary winding wound on one side of the measurement sample 5, and 62 is wound on the other side of the measurement sample 5. secondary winding is shown.

As shown in FIG. 1, in the BH loop tracer, for example, a current i(t) is passed through the primary winding 61 of the measurement sample 5 formed in a ring shape, and the current e flowing through the secondary winding 62 at that time is Measure to determine the magnetic field H(t) and the magnetic flux density B(t). 1, φ(t) is the magnetic flux, N1 is the number of turns of the primary winding 61, and N2 is the number of turns of the secondary winding 62. A number and S indicate the cross-sectional area of the measurement sample 5 around which the windings 61 and 62 are wound.

In this way, when measuring the magnetic properties of a measurement sample (for example, a newly developed magnetic material) using a BH loop tracer, the shape of the measurement sample 5 is preconfigured into a ring shape or parallel cross shape so as to form a magnetic circuit. , and winding the primary winding 61 and the secondary winding 62 around the measurement sample 5 that has been processed.

Therefore, for example, in order to measure and evaluate the magnetic properties of the measurement sample 5, a predetermined amount is required to process the measurement sample into a ring shape or parallel cross shape, and processing may be difficult depending on the material. . In addition, for example, it is troublesome to wind the windings 61 and 62 around the ring-shaped measurement sample 5, which is a major impediment to the development and evaluation of new magnetic materials. It's becoming Furthermore, it is difficult to measure the measurement sample (magnetic material) 5 by applying a high magnetic field (a magnetic field with a large amplitude) at a high frequency (for example, several MHz or more) (at a high frequency and a high magnetic field). It is the limit of the magnetic circuit for measuring.

The application of the magnetic property measuring device and the magnetic property measuring method according to the present invention can be applied, for example, when measuring the magnetic properties of a magnetic material developed for power electronics, with a small amount of sample (measurement sample) and in a short time. Although properties can be measured, it goes without saying that the magnetic properties of a wide range of common substances can be measured.

SUMMARY OF THE INVENTION In view of the problems described above, it is an object of the present invention to provide a magnetic property measuring apparatus and magnetic property measuring method capable of measuring the magnetic properties of a magnetic material at a high frequency and in a high magnetic field. Another object of the present invention is to provide a magnetic property measuring apparatus and a magnetic property measuring method capable of measuring magnetic properties in a short time with a small amount of measurement sample.

According to the first embodiment, a measurement area for measuring the magnetic properties of a measurement sample, a laminated substrate in which a plurality of substrates each having a conductive pattern are laminated, and a high-frequency magnetic field generated by the conductive pattern and applied to the measurement area and a magnetic property measurement unit including a pickup coil for detecting the magnetic property of the measurement sample in the measurement area; a power supply device that supplies power to the excitation coil; a control calculation unit that calculates the magnetic properties of the measurement sample based on the flowing current and the output voltage of the pickup coil, wherein the plurality of conductive patterns used as the excitation coil are connected in series with a capacitor. A magnetic property measuring device that constitutes a resonant circuit is provided.

According to the second embodiment, a series resonance circuit is configured by forming an excitation coil from a plurality of conductive patterns on respective substrates of a laminated substrate, and connecting the plurality of conductive patterns used as the excitation coil in series with a capacitor. 1. A magnetic property measuring method in which a high frequency magnetic field is generated and applied to a measurement area for measuring the magnetic properties of a measurement sample, and the magnetic properties of the measurement sample are detected by a pickup coil in the measurement area to which the high frequency magnetic field is applied. wherein the value of the capacitor is defined based on the frequency for measuring the magnetic properties of the measurement sample, the measurement sample is placed at a predetermined position of the pickup coil, the current flowing through the series resonance circuit and the A magnetic property measuring method is provided for measuring the magnetic property of the measurement sample based on the output voltage of the pickup coil.

According to the magnetic property measuring device and the magnetic property measuring method of the present embodiment, there is a special effect that the magnetic property of a magnetic material can be measured at a high frequency and a high magnetic field. Furthermore, according to the magnetic property measuring device and the magnetic property measuring method of the present embodiment, there is an effect that the magnetic property can be measured with a small amount of measurement sample in a short time.

FIG. 1 is a diagram for explaining an example of a BH loop tracer. FIG. 2 is a diagram schematically showing a magnetic property measuring apparatus of one embodiment according to the present invention. FIG. 3 is a circuit diagram for explaining an exciting coil in the magnetic property measuring section shown in FIG. 4 is a diagram schematically showing an example of the exciting coil shown in FIG. 3. FIG. 5 is a diagram for explaining the arrangement of capacitors in a part of the exciting coil shown in FIG. 4. FIG. FIG. 6 is a diagram for explaining an example of an excitation coil and a pickup coil in the magnetic property measuring section shown in FIG. FIG. 7 is a diagram for explaining another example of the excitation coil and the pickup coil in the magnetic property measuring section shown in FIG. FIG. 8 is a diagram for explaining examples of conductive patterns of the pickup coil and the exciting coil. 9 is a functional block diagram for explaining an example of the operation of the control calculation unit shown in FIG. 2. FIG. FIG. 10 is a diagram for explaining the relationship between coercive force and saturation magnetization. 11A and 11B are diagrams for explaining an example of an excitation coil on which an experiment was performed. FIG. FIG. 12 is an equivalent circuit diagram showing the excitation coil shown in FIG. 11 together with a power supply. 13 is a diagram (part 1) showing measurement results by the excitation coil shown in FIG. 11. FIG. FIG. 14 is a diagram (part 2) showing measurement results by the excitation coil shown in FIG. 11;

Embodiments of the magnetic property measuring device and the magnetic property measuring method according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 2 is a diagram schematically showing a magnetic property measuring apparatus of one embodiment according to the present invention. The magnetic property measuring apparatus shown in FIG. 2 is suitable for, for example, measuring the magnetic properties of a magnetic material (measurement sample) for power electronics, but the measurement sample is not particularly limited.

As shown in FIG. 2 , the magnetic property measuring device of this embodiment includes a power supply device 1 , a magnetic property measuring section 2 , a control calculating section 3 , a voltmeter 41 , an ammeter 42 and a digital oscilloscope 43 . For the power supply device 1, for example, an inverter power supply of 1 to 50 MHz can be applied, and the output frequency, power, etc. are controlled by the control calculation unit 3.

The control calculation unit 3 is composed of, for example, a computer that runs a predetermined program, and includes a computer body 31, a display 32, a keyboard 33, a mouse 34, and the like. The control calculation unit (computer) 3 receives the output of a voltmeter 41 that detects the voltage from the pickup coil 23 and the output of an ammeter 42 that detects the current flowing through the excitation coil 24 via a digital oscilloscope 43, and measures them. Obtain the magnetic properties of the sample 50 . As will be described in detail with reference to FIGS. 11 to 14, the excitation coil 24 can be configured as, for example, a very small solenoid, so that the measurement sample 5 can be measured at a high frequency and a high magnetic field. Magnetic properties can be measured in a short time with a small amount of measurement sample.

The magnetic property measurement unit 2 is a multilayer board (laminated board, multiphase printed circuit board) in which a plurality of boards (printed boards) 2a, 2b, 2c, . . . It can be constructed by stacking layers or more layers. The magnetic property measurement unit 2 is provided with a measurement area 20 for measuring the magnetic properties of the measurement sample 50 . As will be described in detail later, the measurement sample 50 is placed, for example, at a position approximately in the center of the measurement area 20 (an area where the magnetic field (magnetic field) generated by the excitation coil 24 is stable), and detection by the pickup coil 23 is performed. will be

That is, the control calculation unit 3 calculates (detects) the resonance frequency of the excitation coil 24 (resonant circuit), the magnetic field applied to the measurement area 20, etc. based on the current flowing through the excitation coil 24 from the ammeter 42, Based on the output voltage (induced electromotive force) of the pickup coil 23, the induced electromotive force and coercive force of the measurement sample 50 are detected by the applied magnetic field, and the magnetic characteristics such as the magnetization M, coercive force Hc and saturation magnetization Ms of the measurement sample 50 are detected. Calculate

Here, the measurement area 20 provided in the magnetic property measurement unit 2 can be, for example, a cylindrical shape with a diameter and depth (height) of about several millimeters, and the magnetic material (measurement sample 50 ) can be very small compared to, for example, those described with reference to FIG. In addition, the measurement sample 50 can have any shape, such as a granular shape or a block shape, and it is possible to greatly reduce the labor and time required for measurement.

Furthermore, as in experimental examples to be described later with reference to FIGS. 11 to 14, the magnetic property measuring apparatus of the present embodiment detects a strong magnetic field ( Maximum magnetic flux density: For example, since the magnetic properties of the measurement sample 50 can be measured in a state where several tesla (T) is applied, for example, a new magnetic material at the operating frequency to which the next-generation semiconductor device is applied It becomes possible to deal with the measurement of magnetic properties.

Here, the excitation coil 24 is configured as a series resonance circuit (series LC resonance circuit), and for example, a stable frequency (resonance frequency) is applied to the hollow measurement area 20 of the magnetic property measurement unit 2 made of a laminated substrate. It is for generating a magnetic field (magnetic field) of Also, the pickup coil 23 is for measuring the magnetic properties of the measurement sample 50 in the magnetic field generated by the exciting coil 24, the details of which will be described later.

The magnetic properties of the measurement sample 50 measured (calculated) by the magnetic property measuring apparatus of the present embodiment include, for example, magnetization (M), coercive force (Hc) and saturation magnetization (Ms) of the measurement sample. However, it goes without saying that it can be configured to seek other magnetic properties.

FIG. 3 is a circuit diagram for explaining an excitation coil in the magnetic property measuring unit shown in FIG. 2, and FIG. 4 is a diagram schematically showing an example of the excitation coil shown in FIG. FIG. 5 is a diagram for explaining the arrangement of capacitors in a part of the excitation coil shown in FIG. 4, and is a plan view of the magnetic characteristic measurement unit 2 as seen from above.

As shown in FIG. 3, the excitation coil 24 is configured as a series LC resonance circuit in which multiple layers of coils 21 (21a, 21b, . . . ) and capacitors 22 (22a, 22b, . . . ) are connected in series. That is, the coil 21a and the capacitor 22a on the printed circuit board 2a on the first layer, the coil 21b and the capacitor 22b on the printed circuit board 2b on the second layer, . A resonant circuit is formed.

A coil 21k and a capacitor 22k are formed by a conductive pattern on each printed circuit board (for example, the k-th printed circuit board 2k) of the plurality of printed circuit boards 2a, 2b, 2c, . The coil 21k and the capacitor 22k are connected in series to form a resonance circuit of one layer of printed circuit board, and the resonance circuits of each layer are connected in series to constitute the exciting coil 24. FIG.

Here, the capacitor 22k may be formed on each printed circuit board 2k, or may be formed on each printed circuit board 2k using the conductive pattern of the adjacent printed circuit board 2k+1. In order to do so, for example, they can be provided on one or both sides of the laminated substrate via conductive holes (through vias 26) penetrating the laminated substrate.

As shown in FIGS. 4 and 5, the excitation coil 24 corresponds to a plurality of conductive patterns (coils) 21k surrounding the measurement area 20 provided in the magnetic property measurement section (laminated substrate) 2 and the coils 21k. A plurality of capacitors 22 k are connected in series by through vias 26 . That is, the excitation coil 24 generates a high-frequency magnetic field of resonance frequency by a series resonance circuit in which the conductive pattern (21) and the capacitor (22) of each laminated substrate are connected in series, and applies it to the measurement area 20.

For example, the conductive pattern 21k in the k layer is formed as a coil for one turn, but may be formed as a coil for two turns or a plurality of turns. In addition, the k-layer capacitor 22k is provided on one surface of the multilayer substrate, that is, on the upper surface of the magnetic characteristic measuring unit 2, for example, through a through via 26. can also be set to

5, capacitors 22k, 22k+1, 22k+2, . . . corresponding to coils 21k, 21k+1, 21k+2, . It is provided in a circular shape that is a distance. This is suitable when a chip capacitor having a precise capacitance value is used as the capacitor 22, for example.

Furthermore, for example, when the number of substrates constituting the magnetic property measurement unit 2 is very large (for example, more than 100 layers), if a capacitor is provided for each conductive pattern (coil) of each layer, both sides of the laminated substrate Even if it is used, it becomes difficult to place a large number of capacitors. In such a case, instead of providing a capacitor for each layer of coil, one capacitor may be provided for multiple layers of coils (eg, three-layer or five-layer coils).

FIG. 6 is a diagram for explaining an example of an excitation coil and a pickup coil in the magnetic property measuring section shown in FIG. In FIG. 6, the excitation coils 24 (24α, 24β) are only coils formed by the conductive patterns 21 formed on the respective substrates, and the capacitors 22 are omitted.

As shown in FIG. 6, the pickup coil 23 is for measuring the magnetic properties of the measurement sample 50, and for example, a conductive pattern (second 1 conductive pattern), the uppermost coil 23α formed by the conductive pattern (second conductive pattern) formed on the top substrate (2a), and the conductive pattern (third conductive pattern) formed on the bottom substrate (2a). It has a lowermost coil 23β with a conductive pattern).

Here, for the central coil 23γ, a conductive pattern formed on a substrate (central substrate) at a position corresponding to the sample placement portion 25 where the measurement sample 50 is placed in the measurement area 20 is used. In addition, the uppermost coil 23α and the lowermost coil 23β are connected so as to be in a first rotation direction (for example, counterclockwise direction) with respect to the central axis CP of the measurement area 20, and the central coil 23γ is connected to the measurement area. 20 so as to be in a second rotational direction opposite to the first rotational direction (for example, clockwise) with respect to the central axis CP.

The measurement sample 50 is, for example, placed in a measurement container having a shape (cylindrical or spherical with an inner diameter slightly smaller than the inner diameter of the measurement area 20) that can move in the measurement area 20 as a powder, or An individual measurement sample 50 having a shape smaller than the measurement area 20 is attached to a measurement jig, and various known positioning techniques are applied to place the measurement sample 50 at a position corresponding to the sample placement section 25. can be done.

The excitation coil 24 includes a first excitation coil 24α and a second excitation coil 24β that are configured with the same number of conductive patterns. The first exciting coil 24α is arranged between the center coil 23γ (first conductive pattern) and the top coil 23α (second conductive pattern), and the second exciting coil 24β is arranged between the center coil 23γ and the bottom coil 23β. It is arranged between (third conductive patterns). Here, the magnetic fields at the surface ends (top coil 23α and bottom coil 23β) of the finite solenoid (excitation coil 24: first excitation coil 24α and second excitation coil 24β) are equal.

As a result, the pick-up coil 23 shown in FIG. Only the influence of the measurement sample 50 on the sample placement section 25 is canceled out and is detected by the central coil 23γ. In this case, the pickup coil 23 can be composed of a central coil 23γ in the center of the excitation coil 24 (solenoid) and uppermost and lowermost coils 23α and 23β at both ends. It becomes possible to shorten the excitation coil 24 (height of 24α, 24β)).

FIG. 7 is a diagram for explaining another example of the excitation coil and the pickup coil in the magnetic property measuring section shown in FIG. As shown in FIG. 7, the pickup coil 23' is a coil (fourth coil) formed on the substrate near the center of the laminated substrate 2 to which the high-frequency magnetic field generated by the exciting coil 24 is stably applied in the measurement area 20. As shown in FIG. to the seventh conductive pattern).

Here, the fourth conductive pattern 23γ ₁ ' and the fifth conductive pattern 23γ ₂ ' are connected so as to be in the first rotation direction (for example, counterclockwise direction) with respect to the central axis CP of the measurement area 20, and laminated. It is formed on two adjacent substrates of the substrate 2 . In addition, the sixth conductive pattern 23α' and the seventh conductive pattern 23β' are arranged to rotate in a second rotating direction opposite to the first rotating direction (for example, clockwise) with respect to the central axis CP of the measurement area 20. Connected.

The sixth conductive pattern 23α' is formed on a substrate between two adjacent substrates (23γ ₁ ', 23γ ₂ ') and one end substrate (uppermost substrate) of the laminated substrate (2). 23β' is formed on the substrate between the two adjacent substrates and the other end substrate (lowermost substrate) of the laminated substrate (2). The number of substrates (the number of coils: distance) between the two adjacent substrates and the substrate on which the sixth conductive pattern 23α' is formed is is equal to the number of substrates between In addition, the fourth and fifth conductive patterns (two-turn coils) 23γ _{1 ′} and 23γ ₂ ′ are formed on two adjacent substrates at positions corresponding to the sample placement portion 25 on which the measurement sample 50 is placed.

As a result, in the pickup coil 23' shown in FIG _. ', 23γ ₂ ', and only the influence of the measurement sample 50 on the sample placement portion 25 is detected by the fourth and fifth conductive patterns 23γ ₁ ', 23γ ₂ '.

In this case, as described above, the fourth to seventh conductive patterns 23γ ₁ ', 23γ ₂ ', 23α', 23β' are all arranged in the region where the magnetic field generated by the exciting coil 24 is stable. preferable. Furthermore, only the fourth and fifth conductive patterns 23γ ₁ ' and 23γ ₂ ' are located on the measurement sample 50 (sample placement portion 25), and the sixth and seventh conductive patterns 23α' and 23β' are located from the sample placement portion 25. It is preferable to place it in a position away from the influence of the magnetic field change due to the measurement sample 50 . Needless to say, the pickup coils applied to the magnetic property measuring apparatus of this embodiment are not limited to the pickup coils 23 and 23' shown in FIGS. 6 and 7 described above.

FIG. 8 is a diagram for explaining examples of conductive patterns of the pickup coil and the exciting coil. Here, in FIG. 8(a), the same conductive pattern 21n is formed on all the substrates (printed substrates) 2n of the laminated substrate (magnetic property measuring section) 2, and for example, the pickup coil 23 shown in FIG. The conductive pattern (third conductive pattern) formed on the uppermost substrate (2a) used as the uppermost coil 23α is not used as the coil constituting the excitation coil 24.

That is, FIG. 8(a) shows a conductive pattern used as the coil 21 constituting the exciting coil 24, coils 23α, 23β and 23γ in the pickup coil 23, and coils 23α', 23β' and 23γ in the pickup coil 23'. ₁ ' and 23γ ₂ ' have the same shape, and the pickup coils 23 and 23' are formed from conductive patterns on a substrate that are not used as the exciting coil 24. FIG.

FIG. 8(b) shows that conductive patterns 21n (21) used as exciting coils 24 are formed on all substrates 2n constituting the laminated substrate 2, and furthermore, the pickup coil 23 shown in FIG. For the uppermost substrate (2a) used as the upper coil 23α, the case of forming the conductive pattern 27 for the pickup coil 23 inside the conductive pattern 21n is shown.

That is, in FIG. 8(b), the exciting coil 24 is composed of the conductive patterns 21n (21) formed on all the substrates 21n of the laminated substrate 2, and the coils 23α, 23β, 23γ in the pickup coil 23 and the pickup The coils 23α', 23β', 23γ ₁ ', 23γ ₂ ' in the coil 23' are configured by the conductive pattern 27 formed inside the conductive pattern 21n used for the exciting coil 24. FIG.

Here, unlike the conductive pattern 21 used for the excitation coil 24, the conductive pattern 27 used for the pickup coil 23 does not carry a large current (does not handle large power). The width and thickness of the metal pattern) do not have to be large.

9 is a functional block diagram for explaining an example of the operation of the control calculation unit shown in FIG. 2. FIG. As shown in FIG. 9, the control calculation unit 3 can be configured by a computer, and includes a power supply control function 311 for controlling the output voltage and frequency of the power supply 1, and a current flowing through the excitation coil 24. The output of the ammeter 42 is received via the digital oscilloscope 43, and the resonance frequency detection function 312 detects the resonance frequency of the magnetic field generated by the exciting coil 24, and the applied magnetic field applied to the measurement area 20 is calculated. It has a calculation function 314 for the applied magnetic field.

Furthermore, the control calculation unit 3 receives the output of the voltmeter 41 that detects the voltage (induced electromotive force) by the pickup coil 23 (23') via the digital oscilloscope 43, and detects the induced electromotive force by the measurement sample 50. It has an induced electromotive force detection function 313 of the applied magnetic field.

The control calculation unit 3 also includes a magnetization calculation function 315 for calculating the magnetization (M) of the measurement sample 50 based on the current flowing through the excitation coil 24 and the output voltage of the pickup coil 23 by the ammeter 42, It has a coercive force detection function 316 that detects the coercive force (Hc) and a saturation magnetization detection function 317 that detects the saturation magnetization (Ms) of the measurement sample 50 . Furthermore, the control calculation unit 3 also has other functions 318 such as other various magnetic properties of the measurement sample 50 .

As described above, the control calculation unit 3 (computer) includes, in addition to the computer main body 31, for example, a keyboard 33 and a mouse 34 for inputting data and instructions, and calculated output data (for example, 10), etc., but it goes without saying that various known variations and modifications can be applied.

FIG. 10 is a diagram for explaining the relationship between coercive force and saturation magnetization. As described above, for example, the magnetic property measuring apparatus of this embodiment can measure the magnetic properties such as the magnetization M, the coercive force Hc, and the saturation magnetization Ms of the measurement sample (magnetic material) 50. Based on these measurement results, For example, a hysteresis curve showing the relationship between coercive force and saturation magnetization can be obtained as shown in FIG.

Here, the magnetic characteristic measuring apparatus of the present embodiment, for example, as in the manufacturing of the excitation coil and the experimental example described below, has a high frequency (resonance frequency) of several MHz to several tens of MHz, and several T As a result, it is possible to measure the magnetic properties of new magnetic materials at the operating frequencies of next-generation semiconductor devices. becomes.

Next, with reference to FIGS. 11 to 14, fabrication of an exciting coil (exciting solenoid coil) and experimental results thereof will be described. FIG. 11 is a diagram for explaining an example of an excitation coil on which an experiment was conducted, and FIG. 12 is an equivalent circuit diagram showing the excitation coil shown in FIG. 11 together with a power supply device.

Here, FIG. 11(a) is a plan view of the magnetic property measurement unit (laminated substrate) 2 viewed from above, and corresponds to FIG. 5 described above, and FIG. 4 schematically shows the conductive pattern 21 formed on each substrate in FIG. 4, and corresponds to the one in which the capacitor 22, the through via 26, and the like are omitted in FIG. FIG. 11(c), which corresponds to FIG. 3 described above, is a circuit diagram for explaining the exciting coil 24 formed of a 16-layer laminated substrate. In FIG. 12, the inverter power supply 1 generates a rectangular wave voltage with a frequency of about 5 MHz, for example, by means of two voltage sources of voltage Vin, a capacitor of capacitance Ccd, and a switch SW, and applies it to the excitation coil 24. It is designed to

First, for the excitation coil 24 that was fabricated and tested, a measurement area 20 with an inner diameter of 2 mm and a length (depth) of 2 mm was formed on a laminated board in which 16 layers of boards (printed boards) were laminated. The specifications of the exciting coil 24 are an inductance of 0.45 μH (0.028 μH per turn), a capacitance of 2.25 nF (36 nF per turn), and a resonance frequency of about 5 MHz.

In addition, the power supply device 1 uses an easily available inverter power supply, so that the resonance frequency of the LC resonance circuit of the excitation coil 24 is around 5 MHz. Here, as the capacitor 22, a laminated ceramic capacitor having a small voltage dependence of capacitance is used.

Here, if a magnetic field of 2 T is to be generated in the exciting coil 24, 280 A (max) must flow, and a voltage of 7 kV will be applied across the exciting coil 24 at this time. Therefore, as shown in FIGS. 11(a) to 11(c), a 16-layer printed circuit board is used to mount one capacitor 22 arranged circumferentially for each coil (conductive pattern 21) of one turn. , was designed as a 16-stage LC series resonant circuit. At this time, since an operation of about several μs is sufficient for measurement, the heat generation of the exciting coil 24 does not pose a problem, and the inverter power supply 1 can be used with a current greatly exceeding its steady-state rating.

That is, as shown in FIG. 12, in the inverter power supply 1 and the excitation coil 24, the excitation coil 24 has Lcoil=0.45 μH and Ccoil=2.25 nF, and the excitation coil 24 is an inverter power supply (half-bridge inverter). 1 and a rectangular wave voltage is applied to generate a sinusoidal current. Rcoil represents the impedance of the exciting coil 24, icoil represents the current flowing through the exciting coil 24 (corresponding to the current detected by the ammeter 42), and vcoil represents the voltage across the exciting coil 24.

13 and 14 are diagrams showing measurement results by the excitation coil shown in FIG. 11. FIG. Here, FIGS. 13(a) and 13(b) were measured by connecting the exciting coil 24 alone to the LCR meter, and FIG. 13(a) shows the measurement results of the frequency and impedance of the exciting coil 24. 13(b) shows the measurement results of the excitation coil 24 frequency and AC resistance. FIG. 14(a) shows the measurement result of the current value flowing through the exciting coil 24 when Vin=40 [V] of the inverter power supply 1 shown in FIG. FIG. 14(b) is a diagram showing the result of measuring the voltage applied to each turn of the excitation coil 24. As shown in FIG.

As shown in FIG. 13(a), the resonance frequency of the excitation coil 24 was around the design value of 5 MHz (f _R =4.7 MHz), and the impedance at that time was 1.39Ω. From the impedance at the resonance frequency, it can be seen that a power supply voltage of about 400V is required to generate a magnetic field of 2T.

As shown in FIG. 14(a), it can be seen that the time until resonance rises is approximately 2 μs. This result agrees well with the result of the simulation of the measured value using the actually measured value. It takes about 10 μs as a whole.

That is, when the magnetic properties of the measurement sample 50 are measured, the time for which the current is passed through the excitation coil 24 can be set to a short time of about 10 μs. It is possible to prevent pattern melting, burnout, etc.). In this experiment, a maximum current of 32 A (max) can be applied to the exciting coil 24, which corresponds to a magnetic field of 0.23 T. Therefore, it is considered that a larger current can be conducted.

Furthermore, as shown in FIG. 14(b), since the magnetic flux penetrating the exciting coil 24 is proportional to the voltage applied to the coil, the interlinking magnetic flux of each turn differs. Since the excitation coil 24 has the same cross-sectional area for all turns, it can be said that the fact that the interlinking magnetic fluxes are different means that there is a magnetic field distribution within the coil. A section (stable region) in which a magnetic field is uniformly generated is considered to be about 0.71 mm in a coil length of 2 mm from the 6th layer to the 11th layer. Therefore, for example _, in the pickup _coil 23' described with reference to FIG. Although preferable, for example, in the pickup coil 23 described with reference to FIG. 6, only the first conductive pattern (23γ) needs to be arranged in the stable region. ) can be reduced.

Although the embodiments have been described above, all examples and conditions described herein are described for the purpose of helping to understand the inventive concept as applied to the invention and technology, and the specifically described examples and conditions are It is not intended to limit the scope of the invention. Nor does such statement in the specification indicate advantages or disadvantages of the invention. Although embodiments of the invention have been described in detail, it should be understood that various changes, substitutions and alterations can be made without departing from the spirit and scope of the invention.

1 power supply (inverter power supply)
2 Magnetic property measurement unit (laminated substrate)
2a, 2b, 2c, ... Substrate (printed circuit board)
3 Computer (control calculation unit)
5, 50 Measurement sample (magnetic material)
21, 21k, 21k+1, 21k+2, ..., 23α, 23β, 23γ, 23α', 23β', 23γ', 23γ ₁ ', 23γ ₂ ' conductive pattern (coil)
22, 22k, 22k+1, 22k+2, ... capacitors 23, 23' pickup coils 24, 24α, 24β excitation coils 25 sample placement section 31 computer main body 32 display 33 keyboard 34 mouse 41 voltmeter 42 ammeter 43 digital oscilloscope

Claims (11)

A measurement area for measuring the magnetic properties of a measurement sample, a laminated substrate in which a plurality of substrates each having a conductive pattern formed thereon are laminated, an excitation coil for generating a high-frequency magnetic field from the conductive pattern and applying it to the measurement area, and the measurement a magnetic property measurement unit including a pickup coil for detecting magnetic properties of the measurement sample in the area;
a control calculation unit that controls a power supply device that supplies electric power to the excitation coil and calculates the magnetic characteristics of the measurement sample based on the current flowing through the excitation coil and the output voltage of the pickup coil; ,
The plurality of conductive patterns used as the excitation coil are connected in series with a capacitor to form a series resonance circuit ,
The pickup coil is
a first conductive pattern formed on a central substrate of the laminated substrate and connected in a first rotational direction with respect to the central axis of the measurement area;
a second conductive pattern formed on a substrate at one end of the laminated substrate, connected to the central axis of the measurement area in a second rotational direction opposite to the first rotational direction;
a third conductive pattern formed on the substrate at the other end of the laminated substrate, connected so as to be in the second rotation direction with respect to the central axis of the measurement area;
A magnetic property measuring device characterized by: The excitation coil includes a first excitation coil and a second excitation coil configured with the same number of the conductive patterns,
The first exciting coil is arranged between the first conductive pattern and the second conductive pattern,
The second excitation coil is arranged between the first conductive pattern and the third conductive pattern,
The magnetic property measuring apparatus according to claim 1 , characterized in that: A measurement area for measuring the magnetic properties of a measurement sample, a laminated substrate in which a plurality of substrates each having a conductive pattern formed thereon are laminated, an excitation coil for generating a high-frequency magnetic field from the conductive pattern and applying it to the measurement area, and the measurement a magnetic property measurement unit including a pickup coil for detecting magnetic properties of the measurement sample in the area;
a control calculation unit that controls a power supply device that supplies electric power to the excitation coil and calculates the magnetic characteristics of the measurement sample based on the current flowing through the excitation coil and the output voltage of the pickup coil; ,
The plurality of conductive patterns used as the excitation coil are connected in series with a capacitor to form a series resonance circuit ,
The pickup coil is
fourth and fifth conductive patterns formed on two adjacent substrates of the laminated substrate and connected in a first rotation direction with respect to the central axis of the measurement area;
connected in a second rotational direction opposite to the first rotational direction with respect to the central axis of the measurement area, and formed on the substrate between the two adjacent substrates and the substrate at one end of the laminated substrate. a sixth conductive pattern;
a seventh conductive pattern formed on a substrate between the two adjacent substrates and the substrate at the other end of the laminated substrate, the seventh conductive pattern being connected in the second rotational direction with respect to the central axis of the measurement area; including,
A magnetic property measuring device characterized by: The number of substrates between the two adjacent substrates and the substrate on which the sixth conductive pattern is formed is equal to the number of substrates between the two adjacent substrates and the substrate on which the seventh conductive pattern is formed. ,
4. The magnetic property measuring apparatus according to claim 3 , characterized in that: The fourth and fifth conductive patterns and the sixth and seventh conductive patterns are formed on a substrate near the center of the laminated substrate to which the high-frequency magnetic field generated by the excitation coil is stably applied,
5. The magnetic property measuring apparatus according to claim 4 , characterized in that: The capacitor is provided on at least one of both surfaces of the laminated substrate via a conductive hole penetrating the laminated substrate,
6. The magnetic property measuring apparatus according to any one of claims 1 to 5, characterized in that: The value of the capacitor is defined based on the frequency for measuring the magnetic properties of the measurement sample,
7. The magnetic property measuring apparatus according to claim 6 , wherein: The pickup coil and the excitation coil are formed by conductive patterns of substantially the same shape formed on respective substrates of the laminated substrate,
The pickup coil is formed by a conductive pattern on a substrate that is not used as the excitation coil.
8. The magnetic property measuring apparatus according to any one of claims 1 to 7 , characterized in that: The pickup coil and the excitation coil are formed of conductive patterns of different shapes,
The pickup coil is formed of a conductive pattern formed inside a conductive pattern used as the excitation coil,
8. The magnetic property measuring apparatus according to any one of claims 1 to 7 , characterized in that: A plurality of conductive patterns on each substrate of a laminated substrate constitute an excitation coil, and the plurality of conductive patterns used as the excitation coil are connected in series with a capacitor to form a series resonance circuit, generating a high-frequency magnetic field for measurement. applied to the measurement area for measuring the magnetic properties of the sample,
A magnetic property measuring method for detecting magnetic properties of the measurement sample with a pickup coil in the measurement area to which the high-frequency magnetic field is applied,
defining the value of the capacitor based on the frequency for measuring the magnetic properties of the measurement sample;
placing the measurement sample at a predetermined position of the pickup coil;
measuring the magnetic properties of the measurement sample based on the current flowing through the series resonance circuit and the output voltage of the pickup coil ;
The pickup coil is
a first conductive pattern formed on a central substrate of the laminated substrate and connected in a first rotational direction with respect to the central axis of the measurement area;
a second conductive pattern formed on a substrate at one end of the laminated substrate, connected to the central axis of the measurement area in a second rotational direction opposite to the first rotational direction;
a third conductive pattern formed on the substrate at the other end of the laminated substrate and connected in the second rotational direction with respect to the central axis of the measurement area;
The excitation coil includes a first excitation coil and a second excitation coil configured with the same number of the conductive patterns,
The first exciting coil is arranged between the first conductive pattern and the second conductive pattern,
The second excitation coil is arranged between the first conductive pattern and the third conductive pattern ,
A magnetic property measuring method characterized by: A plurality of conductive patterns on each substrate of a laminated substrate constitute an excitation coil, and the plurality of conductive patterns used as the excitation coil are connected in series with a capacitor to form a series resonance circuit, generating a high-frequency magnetic field for measurement. applied to the measurement area for measuring the magnetic properties of the sample,
A magnetic property measuring method for detecting magnetic properties of the measurement sample with a pickup coil in the measurement area to which the high-frequency magnetic field is applied,
defining the value of the capacitor based on the frequency for measuring the magnetic properties of the measurement sample;
placing the measurement sample at a predetermined position of the pickup coil;
measuring the magnetic properties of the measurement sample based on the current flowing through the series resonance circuit and the output voltage of the pickup coil ;
The pickup coil is
fourth and fifth conductive patterns formed on two adjacent substrates of the laminated substrate and connected in a first rotation direction with respect to the central axis of the measurement area;
connected in a second rotational direction opposite to the first rotational direction with respect to the central axis of the measurement area, and formed on the substrate between the two adjacent substrates and the substrate at one end of the laminated substrate. a sixth conductive pattern;
a seventh conductive pattern formed on a substrate between the two adjacent substrates and the substrate at the other end of the laminated substrate, the seventh conductive pattern being connected in the second rotational direction with respect to the central axis of the measurement area; including
The number of substrates between the two adjacent substrates and the substrate on which the sixth conductive pattern is formed is equal to the number of substrates between the two adjacent substrates and the substrate on which the seventh conductive pattern is formed. ,
The fourth and fifth conductive patterns and the sixth and seventh conductive patterns are formed on a substrate near the center of the laminated substrate to which the high-frequency magnetic field generated by the excitation coil is stably applied,
A magnetic property measuring method characterized by:

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