JP5609398B2 - Magnetic field probe - Google Patents

Description

  The present invention relates to a magnetic field probe suitable for use in detecting a magnetic field.

  As a magnetic field probe according to the prior art, a magnetic field detection unit composed of a loop pattern is provided on a substrate, and a transmission line unit composed of, for example, a microstrip line or a strip line is connected to the detection unit. A device in which a capacitor is formed between them is known (for example, see Patent Document 1).

JP 2007-187539 A

  By the way, in the magnetic field probe by patent document 1, since the single capacitor | condenser was connected in series with the coil which consists of a loop pattern, a magnetic field can be detected with high sensitivity in the peripheral band of these resonance frequencies. However, when the resonance frequency is set to about several GHz, for example, if the inductance of the detection unit is large, the capacitance of the capacitor required for the resonance frequency becomes very small. In this case, when the magnetic field probe is formed of an inexpensive printed board, the capacitance of the capacitor tends to vary for each magnetic field probe based on variations in the relative permittivity of the printed board and the shape and arrangement of the capacitor electrodes. As a result, there is a problem that variations occur in the resonance frequency at which the sensitivity is improved for each magnetic field probe.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a magnetic field probe that can suppress variations in resonance frequency and improve sensitivity in a desired frequency band. .

In order to solve the above-described problem, a magnetic field probe according to the invention of claim 1 includes a multilayer substrate in which a plurality of insulating layers are laminated in a thickness direction, and a coil provided on the multilayer substrate and having a winding loop pattern. A capacitor composed of two parallel plate electrode patterns opposed to each other while being insulated from each other with the insulating layer interposed therebetween, and a plurality of the capacitors connected in series to the coil, two parallel flat electrode patterns constituting the capacitor has a structure in which one of the parallel plate electrode patterns Ru is formed larger than the other parallel plate electrode pattern.

According to a second aspect of the present invention, the two parallel plate electrode patterns constituting the capacitor include a winding-shaped loop portion that overlaps with the loop pattern and functions as the coil .

According to a third aspect of the present invention, there is provided a magnetic field probe comprising: a multi-layer substrate in which a plurality of insulating layers are laminated in a thickness direction; a coil provided on the multi-layer substrate and having a winding loop pattern; A capacitor composed of two parallel plate electrode patterns opposed to each other in series, and a plurality of capacitors connected in series to the coil, the two parallel plate electrodes forming the capacitor. The pattern includes a winding-shaped loop portion that overlaps with the loop pattern and functions as the coil.

  According to a fourth aspect of the present invention, a plurality of the loop patterns are provided at different positions in the thickness direction across the insulating layer of the multilayer substrate, and adjacent loop patterns in the thickness direction are connected in series using via holes. It is configured to do.

  In a fifth aspect of the present invention, the plurality of loop patterns are all formed in substantially the same winding shape.

  According to the first aspect of the present invention, the capacitor is constituted by the parallel plate electrode patterns facing each other while being insulated from each other with the insulating layer interposed therebetween, and the capacitor is connected in series to the coil. The magnetic field can be detected with high sensitivity in the peripheral band of the resonance frequency. In addition, since a plurality of capacitors are connected in series to the coil, the combined capacity of the plurality of capacitors can be reduced. For this reason, since the capacity of each capacitor can be increased, each parallel plate electrode pattern can be increased, and even if variations in the shape or arrangement of the parallel plate electrode pattern occur for each magnetic field probe, a plurality of capacitors can be obtained. The variation in the combined capacitance of the capacitors can be reduced. As a result, it is possible to suppress variations in the resonance frequency at which the coil and the capacitor are in series resonance, and it is possible to improve the sensitivity of a desired frequency band set in advance.

In addition , since one parallel plate electrode pattern is formed larger than the other parallel plate electrode pattern, even if positional deviation occurs between the pair of parallel plate electrode patterns during manufacturing, the opposing areas of each other can be kept substantially constant. And variation in the capacitance of the capacitor can be suppressed. Thereby, the position shift of the parallel plate electrode pattern is allowed, and variations in the resonance frequency at which the coil and the capacitor resonate in series can be suppressed.

According to the second and third aspects of the invention, since the parallel plate electrode pattern has a winding-shaped loop portion, the loop portions provided in the two parallel plate electrode patterns are opposed to each other. It functions as a part and overlaps with the loop pattern to function as a coil. For this reason, since the coil and the capacitor are connected in series, a magnetic field can be detected with high sensitivity in the peripheral band of the resonance frequency at which they are in series resonance. Furthermore, in a frequency band other than the resonance frequency, the loop portion of the capacitor functions as a part of the coil, and can output a detection signal such as a voltage corresponding to the magnetic field. For this reason, for example, on the lower frequency side than the resonance frequency, the loop portion of the capacitor does not function as a filter but functions as a part of the coil. Therefore, even when detecting a magnetic field in a frequency band other than the resonance frequency, the detection sensitivity is low. The decrease can be suppressed.

  According to the invention of claim 4, the multilayer substrate is provided with a plurality of loop patterns at different positions in the thickness direction, and adjacent loop patterns in the thickness direction are connected to each other in series using via holes. For this reason, a plurality of loop patterns can be connected in series to form a coil having two or more turns, and the inductance can be increased as compared with a one-turn coil to increase the magnetic field detection sensitivity.

  According to the invention of claim 5, since all of the plurality of loop patterns are formed in substantially the same winding shape, the inductance of the coil is increased as compared with the case where the loop patterns have different winding shapes. Can do.

It is a perspective view which shows the magnetic field probe by embodiment of this invention. It is a perspective view which expands and shows the detection part in FIG. 1 in the state which saw through the multilayer substrate. It is explanatory drawing shown in the state which decomposed | disassembled four parallel plate electrode patterns in FIG. 1, and three loop patterns. It is an equalization circuit diagram which shows the capacitor | condenser and coil which were provided in the magnetic field probe in FIG. It is a front view which shows the 1st insulating layer from the surface of the multilayer board | substrate in FIG. 1, and two parallel plate electrode patterns arrange | positioned on the both surfaces. It is a front view which shows the 2nd insulating layer from the surface of the multilayer substrate in FIG. 1, and the parallel plate electrode pattern and loop pattern which are arrange | positioned at the both surfaces. It is a front view which shows the 3rd insulating layer from the surface of the multilayer board | substrate in FIG. 1, and two loop patterns arrange | positioned on the both surfaces. It is a front view which shows the 4th insulating layer from the surface of the multilayer board | substrate in FIG. 1, and two loop patterns arrange | positioned on the both surfaces. It is a front view which shows the 5th insulating layer from the surface of the multilayer substrate in FIG. 1, and the loop pattern and parallel plate electrode pattern which are arrange | positioned on both surfaces. It is a front view which shows the 6th insulating layer from the surface of the multilayer substrate in FIG. 1, and two parallel plate electrode patterns arrange | positioned on the both surfaces. It is explanatory drawing similar to FIG. 3 shown in the state which decomposed | disassembled four parallel plate electrode patterns and three loop patterns of the magnetic field probe by a modification.

  Hereinafter, magnetic field probes according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  1 to 10 show a magnetic field probe 1 according to an embodiment. The magnetic field probe 1 is housed in a cylindrical case 2 made of, for example, a nonmagnetic insulating material and is electrically connected to the signal processing circuit 3. The signal processing circuit 3 detects a magnetic field generated in the vicinity of the detection unit 19 based on detection signals such as voltage and current generated in the detection unit 19 of the magnetic field probe 1. The magnetic field probe 1 includes a multilayer substrate 4 to be described later, a transmission line unit 13 and a detection unit 19 provided on the multilayer substrate 4.

  The multilayer substrate 4 is formed in a flat plate shape extending in parallel with the X axis direction and the Z axis direction, for example, among the X axis direction, the Y axis direction, and the Z axis direction orthogonal to each other. The multilayer substrate 4 is configured by, for example, stacking six insulating layers 5 to 10 in the Y-axis direction that is the thickness direction. At this time, the multilayer substrate 4 has a width dimension of, for example, about several millimeters with respect to the X-axis direction serving as the width direction, and extends along the Z-axis direction serving as the length direction. It is about.

  Moreover, each insulating layer 5-10 is formed in the layer form, for example using the insulating resin material. And the front-end | tip part 4A of the multilayer substrate 4 is located in the one end side (lower end side in FIG. 1) of the Z-axis direction, and the below-mentioned detection part 19 is provided. On the other hand, the base end side of the multilayer substrate 4 extends toward the other end side in the Z-axis direction (upper end side in FIG. 1).

  Ground electrodes 11 and 12 made of, for example, a conductive metal thin film are provided on the front and back surfaces of the multilayer substrate 4 located on both ends in the Y-axis direction. The ground electrodes 11 and 12 are connected to the ground of, for example, the signal processing circuit 3 and are held at the ground potential, and cover substantially the entire surface of the multilayer substrate 4 except for the front end portion 4A of the multilayer substrate 4.

  As shown in FIGS. 1 and 2, the transmission line unit 13 is provided on the multilayer substrate 4, and connects between a detection unit 19, which will be described later, and the signal processing circuit 3. The transmission line portion 13 has a strip conductor 14 (signal electrode) as an elongated conductor pattern made of, for example, a conductive metal thin film. The transmission line unit 13 is configured by a strip line including a strip conductor 14 and ground electrodes 11 and 12 provided on both surfaces of the multilayer substrate 4. Note that the transmission line unit 13 is not limited to a strip line, and may be configured by, for example, a microstrip line in which one ground electrode is omitted.

  The strip conductor 14 is disposed between the insulating layers 7 and 8, and is located in the center portion of the multilayer substrate 4 in the X-axis direction and extends linearly along the Z-axis. The front end side of the strip conductor 14 extends obliquely toward one side in the X-axis direction, and is electrically connected to a parallel plate electrode pattern 20 described later through a via hole 15 penetrating the insulating layers 5 to 7. ing.

  On the other hand, the ground electrodes 11 and 12 are electrically connected to a parallel plate electrode pattern 26 described later through the via holes 16 and 17 and the connection pattern 18. The connection pattern 18 is located between the insulating layers 7 and 8 and is disposed in the vicinity of the strip conductor 14. The connection pattern 18 is formed of a conductor pattern similar to the strip conductor 14, and extends obliquely in the Z-axis direction. Further, the base end side of the connection pattern 18 is connected to the ground electrodes 11 and 12 through the via holes 16 as through-hole vias penetrating the multilayer substrate 4 in the thickness direction, and the tip end side of the connection pattern 18 is connected to the insulating layers 8 to 8. 10 is connected to the connecting portion 26C of the parallel plate electrode pattern 26 through the via hole 17 penetrating through the substrate 10.

  The detection unit 19 is disposed at the front end portion 4A of the multilayer substrate 4 and includes a coil 31 and a capacitor 32 that are configured by four parallel plate electrode patterns 20, 21, 25, and 26 and three loop patterns 22 to 24 described later. , 33.

  The parallel plate electrode pattern 20 is disposed on the front end portion 4A side of the surface of the insulating layer 5 with respect to the ground electrode 11, and is formed using a conductive metal thin film. As shown in FIG. 5, the parallel plate electrode pattern 20 is formed in a substantially U shape from a flat plate portion 20A having a rectangular shape and one end side (right side in FIG. 5) of the flat plate portion 20A in the X-axis direction. The loop portion 20B extends.

  The flat plate portion 20A is formed in a substantially rectangular shape extending in the X-axis direction over a length dimension L1 of about several millimeters, for example, and extending in the Z-axis direction over a length dimension L2 of about several hundred μm to several millimeters, for example. The layer 5 is disposed on the base end side of the multilayer substrate 4 at a position closer to the ground electrode 11 than the loop portion 20B.

  The loop portion 20B is located on one end side (lower side in FIG. 5) in the Z-axis direction with respect to the flat plate portion 20A. The loop portion 20B is formed using an elongated electrode pattern having a width dimension W0 of, for example, about several tens of μm to several hundreds of μm, and is formed in a substantially rectangular winding shape together with the flat plate portion 20A. One end side of the loop portion 20B is provided with a connecting portion 20C extending toward the base end side in the Z-axis direction (upper side in FIG. 5), and the connecting portion 20C does not interfere with the flat plate portion 20A. It is located on the other end side in the direction (left side in FIG. 5). The connecting portion 20C is electrically connected to the strip conductor 14 through the via hole 15.

  The loop portion 20B extends in the X-axis direction over, for example, about several mm, and extends in the Z-axis direction over, for example, about several hundred μm to several mm. Thereby, the loop part 20B has comprised the substantially rectangular frame shape parallel to XZ plane with the flat plate part 20A.

  The parallel plate electrode pattern 21 is disposed between the insulating layer 5 and the insulating layer 6 so as to face the parallel plate electrode pattern 20 in the thickness direction, and a conductive metal thin film is formed in the same manner as the parallel plate electrode pattern 20. It is formed using. As shown in FIGS. 5 and 6, the parallel plate electrode pattern 21 is connected to the rectangular flat plate portion 21 </ b> A and both ends of the flat plate portion 21 </ b> A in the X-axis direction and has a substantially U shape. The loop portion 21B extends.

  The flat plate portion 21 </ b> A is disposed at a position facing the flat plate portion 20 </ b> A of the parallel plate electrode pattern 20 in the thickness direction. The flat plate portion 21A is divided into a small portion 21A1 located on the left side and a large portion 21A2 located on the right side by a dividing groove 21C located on the other end side (left side in FIG. 6) with respect to the X-axis direction. It is divided. The flat plate portion 21A composed of the small portion 21A1 and the large portion 21A2 is formed in a rectangular shape larger than the flat plate portion 20A of the parallel plate electrode pattern 20 so as to reliably cover the flat plate portion 20A. For this reason, the length dimension L3 in the X-axis direction and the length dimension L4 in the Z-axis direction of the flat plate portion 21A are larger than the length dimension L1 in the X-axis direction and the length dimension L2 in the Z-axis direction of the flat plate portion 20A, respectively. It is set to a large value.

  The large portion 21A2 faces the flat plate portion 20A of the parallel plate electrode pattern 20 in the thickness direction over substantially the entire surface. A part of the small portion 21A1 faces the left end portion of the flat plate portion 20A of the parallel plate electrode pattern 20 in the thickness direction. The lower left end of the large portion 21A2 of the flat plate portion 20A is electrically connected to the adjacent loop pattern 22 through a via hole 27 described later.

  The loop portion 21B is disposed at a position facing the loop portion 20B of the parallel plate electrode pattern 20 in the thickness direction with the insulating layer 5 interposed therebetween, and is opposed to a loop pattern 22 described later with the insulating layer 6 interposed therebetween. . The loop portion 21B is formed using an elongated electrode pattern having substantially the same size and shape as the loop portion 20B. However, the width dimension W1 of the loop portion 21B is set to a value larger than the width dimension W0 of the loop portion 20B.

  The loop portion 21B has one end connected to the small portion 21A1 of the flat plate portion 21A and the other end connected to the large portion 21A2 of the flat plate portion 21A. The loop portion 21B is formed in a substantially rectangular winding shape together with the flat plate portion 21A.

  The loop pattern 22 is disposed between the insulating layer 6 and the insulating layer 7, and as shown in FIGS. 6 and 7, for example, an elongated electrode made of a conductive metal thin film having the same width W1 as the loop portion 21B. It is formed using a pattern. The loop pattern 22 has a rectangular frame shape with a part cut away, and has a substantially rectangular winding shape as the winding shape formed by the flat plate portion 21A and the loop portion 21B of the adjacent parallel plate electrode pattern 21. Is formed.

  The loop pattern 22 is arranged such that both ends thereof are separated from each other in the X-axis direction. A connection portion 22A is provided on one end side of the loop pattern 22, and the connection portion 22A is electrically connected to a large portion 21A2 of an adjacent parallel plate electrode pattern 21 through a via hole 27 described later. On the other hand, a connection portion 22B is provided on the other end side of the loop pattern 22, and the connection portion 22B is located on the other side (right side in FIG. 7) in the X-axis direction with respect to the connection portion 22A. The connecting portion 22B is electrically connected to the adjacent loop pattern 23 through a via hole 28 described later.

  The loop pattern 22 extends in the X-axis direction over the length dimension L5, and extends in the Z-axis direction over the length dimension L6. Thus, the loop pattern 22 has a substantially rectangular frame shape parallel to the XZ plane, and faces the loop portion 21B of the parallel plate electrode pattern 21 in the thickness direction with the insulating layer 6 interposed therebetween.

  The loop pattern 23 is disposed between the insulating layer 7 and the insulating layer 8, and as shown in FIGS. 7 and 8, for example, an elongated electrode made of a conductive metal thin film having the same width dimension W1 as the loop pattern 22 It is formed using a pattern. The loop pattern 23 has a rectangular frame shape with a part cut away, and is formed in a substantially rectangular winding shape as the adjacent loop pattern 22. Further, the loop pattern 23 is arranged such that both ends thereof are separated from each other in the X-axis direction, and extends along the loop pattern 22 from one end side to the other end side.

  On one end side of the loop pattern 23, a connection portion 23A is provided at a position facing the connection portion 22B of the loop pattern 22. The connecting portion 23A is electrically connected to a connecting portion 22B of the adjacent loop pattern 22 through a via hole 28 described later. On the other hand, a connection portion 23B is provided on the other end side of the loop pattern 23, and the connection portion 23B is located on the other side in the X-axis direction (right side in FIG. 8) than the connection portion 23A. The connecting portion 23B is electrically connected to the adjacent loop pattern 24 through a via hole 29 described later.

  Similarly to the loop pattern 22, the loop pattern 23 extends in the X-axis direction over the length dimension L5 and extends in the Z-axis direction over the length dimension L6. Thus, the loop pattern 23 has a substantially rectangular frame shape parallel to the XZ plane, and faces the loop pattern 22 in the thickness direction with the insulating layer 7 interposed therebetween.

  The loop pattern 24 is disposed between the insulating layer 8 and the insulating layer 9, and as shown in FIGS. 8 and 9, for example, an elongated electrode made of a conductive metal thin film having the same width W1 as the loop pattern 23 It is formed using a pattern. The loop pattern 24 has a rectangular frame shape with a part cut away, and is formed in a substantially rectangular winding shape as the adjacent loop pattern 23. In addition, the loop pattern 24 is disposed such that both ends thereof are separated from each other in the X-axis direction, and extends along the loop pattern 23 from one end side to the other end side.

  On one end side of the loop pattern 24, a connection portion 24A is provided at a position facing the connection portion 23B of the loop pattern 23. The connecting portion 24A is electrically connected to a connecting portion 23B of the adjacent loop pattern 23 through a via hole 29 described later. On the other hand, a connection portion 24B is provided on the other end side of the loop pattern 24, and the connection portion 24B is located on the other side in the X-axis direction (right side in FIG. 9) than the connection portion 24A. The connecting portion 24B is electrically connected to the adjacent parallel plate electrode pattern 25 through a via hole 30 described later.

  Similarly to the loop pattern 23, the loop pattern 24 extends in the X-axis direction over the length dimension L5, and extends in the Z-axis direction over the length dimension L6. As a result, the loop pattern 24 has a substantially rectangular frame shape parallel to the XZ plane, and faces the loop pattern 23 in the thickness direction with the insulating layer 8 interposed therebetween.

  The parallel plate electrode pattern 25 is disposed between the insulating layer 9 and the insulating layer 10 so as to oppose the loop pattern 24 in the thickness direction, and is formed using a conductive metal thin film, for example, similarly to the loop pattern 24. Has been. The parallel plate electrode pattern 25 is formed, for example, in a line symmetric shape (left and right symmetric shape) with respect to a straight line parallel to the Z axis direction passing through the parallel plate electrode pattern 21 and the center position in the X axis direction. Therefore, like the parallel plate electrode pattern 21, the parallel plate electrode pattern 25 is connected to the rectangular plate portion 25A and both ends of the flat plate portion 25A in the X-axis direction and is substantially U-shaped. And a loop portion 25B extending.

  The flat plate portion 25A is disposed at a position facing the flat plate portion 26A of the parallel plate electrode pattern 26 described later in the thickness direction. The flat plate portion 25A is divided into a small portion 25A1 located on the right side and a large portion 25A2 located on the left side by a dividing groove 25C located on one end side (right side in FIG. 10) with respect to the X-axis direction. Has been. The flat plate portion 25A composed of the small portion 25A1 and the large portion 25A2 has a length dimension L3 in the X-axis direction and a length dimension L4 in the Z-axis direction, and is larger than the flat plate portion 26A of the parallel plate electrode pattern 26. It is formed in a large rectangular shape.

  The large portion 25A2 faces the flat plate portion 26A of the parallel plate electrode pattern 26 in the thickness direction over substantially the entire surface. A part of the small portion 25A1 faces the right end portion of the flat plate portion 26A of the parallel plate electrode pattern 26 in the thickness direction. The lower right end of the large portion 25A2 of the flat plate portion 25A is electrically connected to the adjacent loop pattern 24 through a via hole 30 described later.

  The loop portion 25B is located on one end side (lower side in FIG. 10) in the Z-axis direction with respect to the flat plate portion 25A. The loop portion 25B is opposed to the loop pattern 24 in the thickness direction with the insulating layer 9 interposed therebetween, and at a position opposed to the loop portion 26B of the parallel plate electrode pattern 26 described later with the insulating layer 10 interposed therebetween. Has been placed. The loop portion 25B is formed using an elongated electrode pattern having a width dimension W1.

  The loop portion 25B has one end connected to the large portion 25A2 of the flat plate portion 25A and the other end connected to the small portion 21A1 of the flat plate portion 25A. The loop portion 25B is formed in a substantially rectangular winding shape together with the flat plate portion 25A.

  The parallel plate electrode pattern 26 is disposed on the back surface of the insulating layer 10 on the tip end 4A side with respect to the ground electrode 12, and is formed using a conductive metal thin film. The parallel plate electrode pattern 26 is formed, for example, in a line-symmetrical shape (left and right symmetrical shape) with respect to a straight line parallel to the Z-axis direction passing through the parallel plate electrode pattern 20 and the center position in the X-axis direction. Therefore, as shown in FIG. 10, the parallel plate electrode pattern 26 is connected to the rectangular flat plate portion 26A and both ends of the flat plate portion 26A in the X-axis direction and extends in a substantially U shape. And the loop portion 26B.

  The flat plate portion 26A, like the flat plate portion 20A, is formed in a substantially rectangular shape with a length dimension L1 in the X-axis direction and a length dimension L2 in the Z-axis direction. The flat plate portion 26A is disposed at a position facing the flat plate portion 25A in the thickness direction, and is formed in a rectangular shape smaller than the flat plate portion 25A. For this reason, the length dimension L1 in the X-axis direction and the length dimension L2 in the Z-axis direction of the flat plate portion 26A are respectively larger than the length dimension L3 in the X-axis direction and the length dimension L4 in the Z-axis direction of the flat plate portion 25A. It is set to a small value.

  The loop portion 26B is located on one end side (lower side in FIG. 10) in the Z-axis direction with respect to the flat plate portion 26A. The loop portion 26B is disposed at a position facing the loop portion 25B. The loop portion 26B is formed using an elongated electrode pattern having a width dimension W0, and is formed in a substantially rectangular winding shape together with the flat plate portion 20A. The width dimension W0 of the loop portion 26B is set to a value smaller than the width dimension W1 of the loop portion 25B. The other end side of the loop portion 26B is provided with a connection portion 26C extending toward the base end side (upper side in FIG. 10) in the Z-axis direction, and the connection portion 26C does not interfere with the flat plate portion 26A. It is located on one end side in the axial direction (right side in FIG. 10). The connection portion 26C is electrically connected to the connection pattern 18 through the via hole 17. The loop part 26B has a substantially rectangular frame shape parallel to the XZ plane together with the flat plate part 26A.

  Thus, the loop portions 20B, 21B, 25B, and 26B and the loop patterns 22 to 24 of the parallel plate electrode patterns 20, 21, 25, and 26 and the loop patterns 22 to 24 are formed in substantially the same winding shape, and the X-axis direction of the multilayer substrate 4 Are disposed at substantially the same position with respect to the Z-axis direction. Thereby, loop part 20B, 21B, 25B, 26B and loop pattern 22-24 have mutually overlapped with respect to the thickness direction over substantially full length except for connection part 20C, 26C.

  The via hole 27 is located between the parallel plate electrode pattern 21 and the loop pattern 22 in the thickness direction and penetrates the insulating layer 6 and is formed by covering the inner wall with a conductive material such as a metal material. Has been. The via hole 27 is disposed at a position corresponding to the large portion 21A2 of the parallel plate electrode pattern 21 and the connection portion 22A of the loop pattern 22, and electrically connects the parallel plate electrode pattern 21 and the loop pattern 22 in series.

  The via hole 28 is located between the loop patterns 22 and 23 in the thickness direction, penetrates the insulating layer 7 and is formed in the same manner as the via hole 27. The via hole 28 is disposed at a position corresponding to the connection portion 22B of the loop pattern 22 and the connection portion 23A of the loop pattern 23, and electrically connects the loop pattern 22 and the loop pattern 23 in series.

  The via hole 29 is located between the loop patterns 23 and 24 in the thickness direction, penetrates the insulating layer 8 and is formed in the same manner as the via hole 27. The via hole 29 is disposed at a position corresponding to the connection portion 23B of the loop pattern 23 and the connection portion 24A of the loop pattern 24, and electrically connects the loop pattern 23 and the loop pattern 24 in series.

  The via hole 30 is located between the loop pattern 24 and the parallel plate electrode pattern 25 in the thickness direction, penetrates the insulating layer 9 and is formed in the same manner as the via hole 27. The via hole 30 is disposed at a position corresponding to the connection portion 24B of the loop pattern 24 and the large portion 25A2 of the parallel plate electrode pattern 25, and electrically connects the loop pattern 24 and the parallel plate electrode pattern 25 in series.

  As a result, the parallel plate electrode patterns 21 and 25 and the loop patterns 22 to 24 are connected in series with each other using the via holes 27 to 30 to constitute a coil 31 having approximately five turns (five turns). The coil 31 detects a magnetic field in the Y-axis direction (thickness direction) passing through the loop portions 21B and 25B of the parallel plate electrode patterns 21 and 25 and the loop patterns 22 to 24, and a voltage corresponding to a change in magnetic flux. The detection signal is output.

  On the other hand, the parallel plate electrode patterns 20, 21 face each other while being insulated from each other, and constitute a capacitor 32. Similarly, the parallel plate electrode patterns 25 and 26 face each other while being insulated from each other, and constitute a capacitor 33. Thereby, the coil 31 and the capacitors 32 and 33 are electrically connected in series with each other by sharing the parallel plate electrode patterns 21 and 25. At this time, one end side of the capacitor 32 is electrically connected to the strip conductor 14 of the transmission line portion 13 through the connection portion 20 </ b> C, and the other end side of the capacitor 32 is electrically connected to one end side of the coil 31. The other end side of the coil 31 is electrically connected to one end side of the capacitor 33. The other end side of the capacitor 33 is electrically connected to the ground electrodes 11 and 12 through the connection portion 26C and the like.

  The magnetic field probe 1 according to the present embodiment has the above-described configuration, and the operation thereof will be described next.

  First, the distal end portion 4A of the magnetic field probe 1 is disposed in the state of being close to the surface of the measurement target (for example, the measurement target substrate). Then, the magnetic field probe 1 is moved on the surface of the measurement target. Here, when a magnetic field in the Y-axis direction is generated on the surface of the measurement object located in the vicinity of the magnetic field probe 1, the magnetic field passes through the loop patterns 22 to 24 and the like of the detection unit 19. Thereby, for example, a voltage as a detection signal is generated in the coil 31, and by detecting this voltage, a magnetic field generated on the surface of the measurement object can be detected.

  However, in the present embodiment, the capacitor 32 is configured by the parallel plate electrode patterns 20 and 21 that face each other while being insulated from each other with the insulating layer 5 interposed therebetween, and are opposed to each other while being insulated from each other with the insulating layer 10 interposed therebetween. A capacitor 33 was constituted by the parallel plate electrode patterns 25 and 26. In addition, since these capacitors 32 and 33 are connected in series to the coil 31, a magnetic field can be detected with high sensitivity in the peripheral band of the resonance frequency at which the coil 31 and the capacitor 33 resonate in series. Since a plurality of capacitors 32 and 33 are connected in series to the coil 31, the combined capacity of the plurality of capacitors 32 and 33 can be reduced, and variations in the combined capacity can be suppressed.

  More specifically, for example, when the inductance L of the coil is 30 nH, the capacitance necessary to resonate at 2.5 GHz is about 0.135 pF. In order to form this capacitance using a single capacitor, for example, when an insulating layer having a thickness of 0.06 mm and a relative dielectric constant of 3.6 is used, parallel plates facing each other with the insulating layer interposed therebetween The electrode pattern needs the same area as a square having a side of 0.504 mm. Since the processing accuracy of a conductor pattern formed on a general printed circuit board is about ± 0.05 mm, the actual capacitance value is 0.110 to 0.163 pF. At this time, since the resonance frequency is 2.24 to 2.73 GHz and varies in a range of about 0.5 GHz, it tends to be difficult to manufacture a magnetic field probe whose sensitivity increases in a desired frequency band.

  On the other hand, in the present embodiment, since the two capacitors 32 and 33 are connected in series, the capacitance required per one is 0.270 pF. In this case, even when the insulating layers 5 to 10 are formed under the same conditions as described above, the parallel plate electrode patterns 20, 21, 25, and 26 can be enlarged to the same area as a square having a side of 0.713 mm. The actual capacitance value considering the processing accuracy is 0.117 to 0.155 pF. At this time, since the resonance frequency is 2.30 to 2.64 GHz, the range of variation becomes smaller by about 0.15 GHz than when a single capacitor is used.

  Since the capacitance of each of the capacitors 32 and 33 can be increased in this way, the parallel plate electrode patterns 20, 21, 25 and 26 can be formed with a large area, and the parallel plate electrode for each magnetic field probe 1. Even if variations occur in the shapes, arrangements, etc. of the patterns 20, 21, 25, 26, variations in the combined capacitance of the plurality of capacitors 32, 33 can be reduced. As a result, it is possible to suppress variations in resonance frequency at which the coil 31 and the capacitors 32 and 33 are in series resonance, and it is possible to improve sensitivity in a desired frequency band set in advance.

  Further, among the parallel plate electrode patterns 20 and 21 facing each other, the parallel plate electrode pattern 21 was formed larger than the parallel plate electrode pattern 20. For this reason, even if position shift arises between the parallel plate electrode pattern 20 and the parallel plate electrode pattern 21 at the time of manufacture, mutual opposing area can be hold | maintained substantially constant. Similarly, among the parallel plate electrode patterns 25 and 26 facing each other, the parallel plate electrode pattern 25 is formed larger than the parallel plate electrode pattern 26, so that even if they are misaligned, the facing areas of each other are made substantially constant. Can be held. For this reason, the dispersion | variation in the capacity | capacitance of the capacitors 32 and 33 can be suppressed, the positional offset of the parallel plate electrode patterns 20 and 25 and the parallel plate electrode patterns 21 and 26 is permitted, and the coil 31 and the capacitors 32 and 33 are made. It is possible to suppress variations in resonance frequency that causes series resonance.

  Further, since the parallel plate electrode patterns 20 and 21 of the capacitor 32 include the winding-shaped loop portions 20B and 21B, these loop portions 20B and 21B face each other and function as a part of the capacitor 32. At the same time, it overlaps with the loop patterns 22 to 24 and functions as the coil 31. Similarly, since the parallel plate electrode patterns 25 and 26 of the capacitor 33 include winding-shaped loop portions 25B and 26B, these loop portions 25B and 26B function as a part of the capacitor 33 so as to face each other. At the same time, it overlaps with the loop patterns 22 to 24 and functions as the coil 31.

  For this reason, since the coil 31 and the capacitors 32 and 33 are connected in series, a magnetic field can be detected with high sensitivity in the peripheral band of the resonance frequency at which they are in series resonance. Furthermore, in frequency bands other than the resonance frequency, the loop portions 20B, 21B, 25B, and 26B of the capacitors 32 and 33 function as a part of the coil 31, and can output a detection signal such as a voltage corresponding to the magnetic field. For this reason, for example, on the lower frequency side than the resonance frequency, the loop portions 20B, 21B, 25B, and 26B of the capacitors 32 and 33 do not function as a filter but function as a part of the coil 31, and therefore a frequency band other than the resonance frequency. Even when a magnetic field is detected by this, a decrease in detection sensitivity can be suppressed.

  The multilayer substrate 4 is provided with a plurality of loop patterns 22 to 24 at different positions in the thickness direction, and adjacent loop patterns 22 to 24 in the thickness direction are connected in series using via holes 28 and 29. It was. For this reason, a plurality of loop patterns 22 to 24 can be connected in series to form a coil 31 having two or more turns, and the inductance can be increased as compared with a one-turn coil to increase the magnetic field detection sensitivity. Can do.

  Further, since the plurality of loop patterns 22 to 24 are all formed in substantially the same winding shape, the inductance of the coil 31 is increased as compared with the case where the loop patterns 22 to 24 have different winding shapes. Can do.

  In the above-described embodiment, the case where two capacitors 32 and 33 are connected in series to the coil 31 has been described as an example. However, three or more capacitors may be connected in series to the coil. In this case, the constituent positions of the capacitors may be arranged between any of the plurality of loop patterns arranged in the thickness direction. In addition, the plurality of capacitors may be disposed adjacent to each other in the thickness direction, for example, may be disposed apart from each other in the thickness direction, or may be disposed on both ends in the thickness direction.

  In the embodiment, the parallel plate electrode patterns 20, 21, 25, 26 of the capacitors 32, 33 are provided with the loop portions 20 B, 21 B, 25 B, 26 B that function as the coils 31. However, the present invention is not limited to this, and capacitors 46 and 47 are formed using parallel plate electrode patterns 42, 43, 44, and 45 with the loop portions omitted, such as a magnetic field probe 41 according to the modification shown in FIG. It is good also as composition to do.

  Moreover, in the said embodiment, the parallel plate electrode patterns 20 and 26 located in the both ends side of the thickness direction of the multilayer substrate 4 are formed smaller than the parallel plate electrode patterns 21 and 25 located in the center side of the thickness direction. It was set as the structure to do. However, the present invention is not limited to this, and the parallel plate electrode patterns 20 and 26 may be formed larger than the parallel plate electrode patterns 21 and 25 or may be formed in the same size.

  In the embodiment, the width dimension W0 of the loop portions 20B and 26B located on both end sides in the thickness direction of the multilayer substrate 4 is equal to the loop portions 21B and 25B and the loop pattern 22 located on the center side in the thickness direction. Although the width dimension W0 is set to a value smaller than the width dimension W1 of .about.24, the width dimension W0 of the loop portions 20B and 26B is set to a value larger than the width dimension W1 of the loop portions 21B and 25B and the loop patterns 22-24. It may be set to the same value.

  In the above embodiment, all the loop patterns 22 to 24 have the same width dimension W1 and are formed in the same winding shape (length dimensions L5 and L6). It may have different width dimensions and may be formed in different winding shapes.

  Furthermore, in the said embodiment, although the loop patterns 22-24 were formed in the substantially square shape, you may form other polygonal shapes, such as a triangle and a pentagon, for example, and you may form in a circle, a semicircle, an ellipse etc. Moreover, in the said embodiment, although the loop parts 21B and 25B of the parallel plate electrode patterns 21 and 25 and the loop patterns 22-24 were connected in series and the coil 31 of about 5 turns was formed, 1 to 4 turns The coil may be a 6-turn or more coil.

1,41 Magnetic field probe 4 Multilayer substrate (substrate)
DESCRIPTION OF SYMBOLS 13 Transmission line part 19 Detection part 20, 21, 25, 26, 42, 43, 44, 45 Parallel plate electrode pattern 20B, 21B, 25B, 26B Loop part 22-24 Loop pattern 27-30 Via hole 31 Coil 32, 33, 46, 47 capacitors

Claims (5)

A multilayer substrate in which a plurality of insulating layers are stacked in the thickness direction, a coil provided on the multilayer substrate and formed of a coiled loop pattern, and two parallel electrodes facing each other while being insulated from each other across the insulating layer A capacitor comprising a plate electrode pattern and connected in series to the coil ;
Before SL capacitor is plural serially connected to said coil,
Two parallel flat electrode patterns, a magnetic field probe comprising a structure in which one of the parallel plate electrode patterns Ru is formed larger than the other parallel plate electrode patterns constituting the capacitor. The two parallel flat electrode patterns constituting the capacitor, the magnetic field probe according to claim 1 comprising a structure having a loop portion of the winding shape which functions as the coil overlaps with the loop pattern. A multilayer substrate in which a plurality of insulating layers are stacked in the thickness direction, a coil provided on the multilayer substrate and formed of a coiled loop pattern, and two parallel electrodes facing each other while being insulated from each other across the insulating layer A capacitor comprising a plate electrode pattern and connected in series to the coil;
A plurality of the capacitors are connected in series to the coil,
Two parallel flat electrode patterns, the name Ru magnetic field probe configured to include a loop of the winding shape which functions as the coil overlaps with the loop pattern forming the capacitor.   The loop pattern is provided in a plurality at different positions in the thickness direction across an insulating layer of the multilayer substrate, and adjacent loop patterns in the thickness direction are connected to each other in series using via holes. , 2 or 3 Magnetic field probe.   The magnetic field probe according to claim 4, wherein all of the plurality of loop patterns are formed in substantially the same winding shape.

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