JP4030246B2 - Broadband near-field probe - Google Patents

Description

[0001]
[Industrial application fields]
The present invention is a printed wiring board that detects electromagnetic noise from various electric and electronic devices such as electronic copying machines, facsimiles, printing machines, personal computers, household electrical equipment, industrial equipment, etc., and is embedded in the apparatus. A broadband near-field probe used to detect noise from the etc., and to measure the current. The present invention relates to a so-called near-field probe for detection, and is effective when used in an inspection apparatus for electromagnetic interference countermeasures for examining EMC regulation countermeasures for various electronic devices.
[0002]
[Prior art]
Conventionally, EMC (Electromagnetic Compatibilty) countermeasures, countermeasures from the results of measurements using electromagnetic antennas at a distance of 10m, 30m, etc. in open sites or anechoic chambers defined by legal regulations There is a way to take. Apart from this, there is also a method of detecting the electromagnetic field from the object to be detected with a probe brought close to the measurement at such an authentication site and taking measures against the object. In addition, there is a probe that performs current detection in the vicinity of a relatively large target in which a coil is wound around a cable and used as a loop coil, such as a conventional current probe (Credence probe: US5773974).
In addition, a “magnetic field measurement probe” (Japanese Patent Laid-Open No. Sho 62-106379) for detecting a signal generated only by a magnetic field in a symmetrical loop coil and a circuit in a shield box that follows, a sensor formed by etching on a flexible substrate, “Broadband microwave in-situ test device” (Japanese Patent Laid-Open No. 7-191058) having an output connector at the tip of the elbow, which is composed of a printed circuit board and provided with a shield, “Magnetic probe for electromagnetic noise measurement, electromagnetic There is an electric field probe for noise measurement and an electromagnetic noise measurement device "(Japanese Patent Laid-Open No. 8-248080), and in a probe composed of a metal wire coil, a connector and a resistor, There is an “EMI probe” (Japanese Utility Model Laid-Open No. 4-67977) provided with a shield plate. “Radiation evaluation apparatus and method” (Japanese Patent Laid-Open No. 10-307159), which measures the in-phase noise of a current-carrying cable with a probe and approximates and estimates the radiated electric field noise in the far field from the data. , A negative feedback coil is provided in an element whose impedance change is proportional to the magnetic field intensity, and the “magnetic impedance sensor” (Japanese Patent Laid-Open No. 11-109006), which improves the linearity of the output with respect to the magnetic field, Various things are known.
Also, a near-field probe is made of a thin film, a shield is provided on the transmission line, and the transmission line is made of a triplate structure to reduce measurement errors. There is a “near magnetic field probe, a near magnetic field probe unit, and a near magnetic field probe system” (Japanese Patent Application No. 9-59267), which is configured to improve the positioning accuracy of the location.
[0003]
The outline of the configuration of the loop coil type near-field probe used in the above prior art is basically as shown in FIG. 15 of the present application drawing. The loop coil part 2, the transmission line part 3, and the pad part 4 The conductive metal (non-magnetic metal such as aluminum) foil 1a is cut to form a detection portion, which is composed of an insulating sheet 1b such as an epoxy substrate that also serves as a support member, and a conductive metal foil 1a. (Fig. (A)) is processed into a predetermined shape as described above. The core portion of the connector 5 is connected to the pad portion 4, and the connector is connected to the signal processing portion 7 via the coaxial cable 6.
The near-field probe provided with such a loop coil portion has a high sensitivity in the high frequency band but a low sensitivity in the low frequency band because the loop coil portion is made of a nonmagnetic metal. Therefore, this is not suitable for detecting electromagnetic noise in the low frequency band. Therefore, when using these loop coil type near magnetic field probes, a separate loop coil type near field probe for detecting low frequency band noise is required. Need to use.
[0004]
[Problems to be solved]
Therefore, the present invention is to devise the mechanism of the loop coil type near magnetic field probe including the loop coil part, the conductive line and the pad part, and the signal processing part so as to improve the sensitivity in the low frequency band. That is the subject.
[0005]
[Measures taken to solve the problem]
The means taken in order to solve the above-mentioned problem is that a part of the loop coil part is made of a magnetic metal member on the premise of a loop coil type near-field probe having a loop coil part, a conductive line and pad part, and a signal processing part. This is a magnetoresistive effect element.
[0006]
[Action]
A loop base portion made of a non-magnetic metal such as aluminum and a magnetoresistive element made of a magnetic metal member are integrated to form a loop coil portion. For example, this functions as an integral loop coil in a high frequency band of 100 kHz or higher. Then, an induced voltage, which is a high-frequency signal, is generated according to the change in the magnetic flux density linked in the loop coil, and this is detected by the signal processing unit. Then, the value of the current flowing in the magnetoresistive effect element by the magnetic metal member changes due to the influence of the external magnetic field, and the resistance value of the thin film changes.
For example, in a low frequency band of 100 kHz or less, a magnetoresistive effect element made of a magnetic metal member has a sufficient resistance change rate corresponding to the magnetic field strength, so that a change in DC current applied from the signal processing circuit unit is detected by a reference resistance. Can do.
Therefore, the difference between the sensitivity ranges in the high frequency band and the low frequency band is determined in advance, the corrected output is calibrated, and the respective outputs are synthesized to generate a near magnetic field in a wide band from the high frequency band to the low frequency band. Noise can be detected. It should be noted that a method of switching the output can be adopted for a target whose frequency of the generated electromagnetic wave is known in advance.
By connecting this near magnetic field probe to a measuring instrument such as a spectrum analyzer, it is possible to detect electromagnetic noise and current values of PCP or the like in an actual operating state from 100 kHz to 1 GHz or a wider band with high sensitivity.
[0007]
Embodiment 1
In the first embodiment, a current is applied to the magnetoresistive effect element in the above solution using a portion other than the magnetoresistive effect element of the loop coil.
[Action]
A part of the loop coil, a subsequent transmission line, and a pad are provided. A part of the loop coil, the subsequent transmission line, and the pad part are provided, and a part of the loop coil supplies a current to the magnetoresistive effect element. Therefore, the structure can be simplified and simplified.
[0008]
Embodiment 2
A second embodiment is a semiconductor having a signal processing circuit unit in which a loop coil, a transmission line unit, and a pad unit are partly made of a thin film as a magnetoresistive effect element in the above solution or the first embodiment. That is, it is integrated on the substrate.
[Action]
Since the chip component can be monolithically configured, this can further reduce the size.
[0009]
Embodiment 3
The third embodiment is that the circuit unit for integrating the signal from the loop coil is provided for the near-field probe comprising the loop coil and the transmission line of the above-described solution means, the first embodiment, or the second embodiment.
[Action]
Since the signal obtained by the loop coil is a differential waveform, by integrating the output from the loop coil, a real-time current waveform is obtained for the detection waveform by the magnetoresistive effect element, and the real-time current waveform is obtained for the entire frequency range that can be detected. A current waveform is obtained.
[0010]
【Example】
Next, examples will be described with reference to the drawings.
1. Example 1
The first embodiment is within the scope of the solution (corresponding to claim 1).
Basically, the loop coil 104 is not different from the conventional one shown in FIG. 15, but is different in that a part of the loop is composed of the magnetoresistive effect element 101 made of a film of Fe ₂₀ —Ni ₈₀ .
An example of a method for manufacturing the loop coil 104 of this embodiment is as follows.
Quartz, it is formed by sputtering an _Fe 20 _{-Ni 80} film on an insulating substrate such as glass. This Fe ₂₀ -Ni ₈₀ film is a magnetoresistive film, and the value of the current flowing through the thin film changes due to the influence of an external magnetic field, and as a result, the resistance value of the thin film changes (FIG. 1).
In this case, if the magnetoresistive element is a magnetic metal member, it may be appropriately selected according to the intended magnetic field strength. In addition to the Fe ₂₀ -Ni ₈₀ film, a Ni—Fe film, a CuMo permalloy film, a CoFeB amorphous film, a FeSiCoB amorphous thin film, or the like may be used. Further, the Fe ₂₀ -Ni ₈₀ film can also be produced by a plating method. Although the film thickness is 5 μm this time, it can be appropriately set according to sensitivity and other needs.
[0011]
Next, a pattern is formed by a general photolithography technique used in a semiconductor manufacturing process and RIE (Reactive Ion Etching) using CF ₄ + H ₂ . This pattern linearly becomes a part of the tip of the loop coil 104 and has a shape of width 10 μm × length 200 μm that can function as a magnetoresistive element. Specific dimensions of the width and length of the magnetoresistive element 101 can be appropriately selected depending on the purpose. In addition, an etching method or a wet etching method can also be adopted as a method for forming the pattern by the magnetoresistive effect element. In this case, aqua regia should be used as the etching solution, but another solution may be used for the composition (FIG. 2).
After forming the pattern of the magnetoresistive effect element 101, a SiO ₂ film as the insulating layer 102 is formed by sputtering. Other film forming methods such as EB vapor deposition (Electron Beam) and CVD (Chemical Vapor Deposition) can also be used for the film formation of SiO ₂ . Similarly, a through hole 103 is opened on the magnetoresistive element 101 by a general photolithography technique and RIE using CFe + H ₂ (FIG. 3).
The insulating layer material may be other insulating materials such as Si ₃ N ₄ . Etching of the insulating layer may be wet etching, but when the substrate is also etched, it is necessary to protect the back surface of the substrate with a resist or the like.
As the substrate, an insulating substrate other than quartz or a flexible insulating substrate such as polyethylene terephthalate or polyimide can be adopted.
Depending on the photolithography process, it may be a process that does not require an insulating layer. The insulating layer may be other materials such as a Si nitride film.
Next, a part of the loop coil 104 and the subsequent transmission line 105, the loop coil pad 106, the magnetoresistive effect element cable 108 for applying a direct current to the magnetoresistive effect element 101, and the magnetoresistive effect element pad 107 are sputtered. After the film formation, it is manufactured by the photolithography method in the same manner as the Fe ₂₀ -Ni ₈₀ film. The Al film forming method may be another film forming method such as an evaporation method. The nonmagnetic metal constituting the loop coil base may be Cu, Ag, Au and alloys thereof in addition to the above Al (FIGS. 4 and 5).
The structure of the transmission line unit 105 in this embodiment is a parallel line type, but it can also be a transmission line such as a microstrip type or a triplate type.
A signal processing circuit portion having a block diagram as shown in FIG. 6 is connected on the glass epoxy substrate to the device formed as described above (FIG. 5). In the drawing of this example, the arrangement of the DC power supply for the arithmetic circuit is omitted.
[0012]
The signal processing circuit unit shown in FIG. 6 is a type in which a cable for a magnetoresistive effect element (a cable for supplying a current to the magnetoresistive effect element) and a cable for a loop coil are separately provided. Low frequency noise is removed from the high frequency signal induced in the loop coil 104 by the high pass filter 122 via the coaxial cable 109 and the coaxial cable connector 121, and the sensitivity is adjusted by the loop coil sensitivity correction circuit 123. On the other hand, the signal induced in the magnetoresistive effect element 101 has high frequency noise removed by the low pass filter 126 in the impedance change detection circuit 125 via the magnetoresistive effect element cable 108 and the magnetoresistive effect element cable connector 124. The impedance change is detected and the low frequency signal is extracted. Further, a direct current is applied to the magnetoresistive effect element from the direct current power source via this cable 108 (not shown in FIG. 6).
After that, the sensitivity of the low frequency signal is adjusted by the magnetoresistive effect element sensitivity correction circuit 128,
The high frequency signal is combined with the output combining circuit 128, and the combined signal is sent to the measuring instrument via the coaxial cable connector 129 and the coaxial cable 130.
In the near-field probe of this embodiment, the magnetoresistive effect element portion made of Fe ₂₀ -Ni ₈₀ film and the loop coil base portion made of Al function as an integral loop coil in a high frequency range of about 100 kHz or more, and the interlinkage is formed in the loop. The signal processing unit detects an output voltage proportional to the magnetic flux as a voltage proportional to the high-frequency magnetic field strength.
Further, since the Fe ₂₀ -Ni ₈₀ film has a resistance change rate corresponding to the magnetic field strength sufficiently at about 100 kHz or less, the fluctuation of the direct current applied from the signal processing circuit section can be detected by the reference resistance. By calibrating the output in which the difference between the respective sensitivity ranges is determined and corrected, and synthesizing the outputs, electromagnetic noise in a wide band from a high frequency band to a low frequency band can be detected.
In addition, what is necessary is just to take the system which switches an output for the object for which generation frequency is known beforehand.
By connecting this near-field probe to a measuring instrument such as a spectrum analyzer, a near-field probe that can detect electromagnetic noise such as PCP in actual operation and its current value with high sensitivity from a frequency of 100 kHz or less to 11 GHz or more is realized. The
[0013]
2. Example 2
Example 2 is a specific example of Embodiment 2 (corresponding to claim 2), which will be described with reference to FIGS.
The manufacturing method of the probe of Example 2 is formed by the same method as that of Example 1 as described above. In order to simplify the structure, a part of the wiring of the loop coil 204, the transmission line 205, and the pad 206 are provided to provide a direct current to the magnetoresistive effect element 201. A part of the loop coil 204, the subsequent transmission line 205, and the pad part 206 serve as a part of the loop coil part, and a low frequency signal is detected by the magnetoresistive effect element 201 as in the first embodiment. A signal processing circuit unit that can detect a high-frequency signal with the loop coil 204 is provided as shown in FIG. Since other configurations are the same as those of the first embodiment, the description thereof is omitted.
In this configuration, there is a possibility that the direct current 231 does not flow to a measuring instrument such as a spectrum analyzer. Therefore, it is necessary to avoid this and sufficiently perform a required function. By simplifying the structure, the whole can be reduced in size, and the probes can be easily arrayed.
[0014]
3. Example 3
Example 3 is a specific example of Embodiment 2 (corresponding to claim 3), which will be described with reference to FIGS.
A signal processing circuit unit 320 similar to that shown in FIG. 4 is previously formed on a Si semiconductor substrate by a normal semiconductor process, and an insulating layer 302 and a through hole 303 are further formed. The probe part produced in Example 2 is formed on the Si substrate on which the insulating layer 302 is formed in the same manner. The probe unit and the signal processing circuit unit 320 formed on the Si substrate are connected by a wiring process in a normal semiconductor process. In this case, it is necessary to use a GaAs semiconductor substrate depending on the frequency band of electromagnetic noise to be detected.
According to the third embodiment, the near-field probe having the same function as that of the second embodiment can be made more compact. In the third embodiment, amplification can be performed in the vicinity of the signal source by the amplifier unit, so that the S / N ratio can be further improved and a minute signal can be measured.
[0015]
4). Example 4
Example 4 is a specific example of the third embodiment (corresponding to claim 4), which will be described with reference to FIGS.
In the fourth embodiment, since the signal obtained from the loop coil is a differential waveform, only the output from the loop coil is integrated. A real-time current waveform is obtained for the detection waveform by the magnetoresistive effect element, and a real-time current waveform is obtained for the entire frequency range that can be detected. A specific integration circuit as shown in FIG. 14 is conceivable.
Therefore, a broadband current probe can be easily realized by connecting the probe to an oscilloscope or the like.
[0016]
【effect】
According to the probe of the present invention, it is possible to realize a near-field probe and a current probe that detect electromagnetic noise in a wide band from a high frequency band to a low frequency band, and further, by adopting the configurations of claims 2 and 3. This probe can be miniaturized.
Further, by adopting the configuration of claim 4, real-time current waveform detection is possible.
[Brief description of the drawings]
FIG. 1 is a front view showing a procedure 1 for producing a probe of Example 1. FIG.
2A is a front view showing a procedure 2 for producing a probe of Example 1, and FIG. 2B is a plan view.
3A is a front view showing a procedure 3 for producing the probe of Example 1, and FIG. 3B is a plan view.
4A is a front view showing a procedure 4 for producing the probe of Example 1, and FIG. 4B is a plan view.
5 is a plan view of the probe of Example 1. FIG.
FIG. 6 is a block diagram of a signal processing circuit unit according to the first embodiment.
7A is a front view of the probe tip of Example 2, and FIG. 7B is a plan view.
FIG. 8 is a plan view of the probe of Example 2.
FIG. 9 is a block diagram of a signal processing circuit unit according to the second embodiment.
10 is a plan view showing manufacturing process 1 of the probe of Example 3, and FIG. 10 (b) is a front view.
11A is a plan view of a manufacturing process 2 according to the third embodiment, and FIG. 11B is a front view.
12A is a plan view of a manufacturing process 3 according to the third embodiment, and FIG. 12B is a front view thereof.
FIG. 13 is a block diagram of a signal processing circuit unit according to a fourth embodiment.
FIG. 14 is an equivalent circuit diagram of an integrating circuit unit according to the fourth embodiment.
FIG. 15A is a plan view of a conventional probe creation sequence using a loop coil in the ascending order 1; FIG. 15B is a plan view of a creation procedure 2;
[Explanation of symbols]
1a .... Conductive metal foil 1b .... Insulating layer sheet 2 ... Loop coil 3 ... Transmission line 4 ... ... Pat part 5 ... Connector 6 ... Coaxial cable 7 ... Signal processing part 100 ... Glass Substrate 101, 201 ... Magnetoresistive element 102, 302 ... Insulating film 103, 303 ... Through hole 104, 204 ... ... Loop coils 105, 205 ... Transmission lines 106, 206 ... Loop coil pads 107 ... Magnetoresistive element pads 108 .... Magnetoresistance effect element cables 109, 209 ... Coaxial cables 120, 220 320... Signal processing circuit units 121, 221... Coaxial cable connectors 122 and 222... High pass filters 123 and 223. .. Loop coil sensitivity correction circuit 124... Cable connectors 125 and 225 for magnetoresistive effect elements... Impedance change detection circuits 126 and 226. Low-pass filter 127, 227 ... Magnetoresistive effect element sensitivity correction circuit 128, 228 ... Output synthesis circuit 129, 229 ... Coaxial cable Connectors 130, 230 ... Coaxial cables 131, 231 ... DC power supply 400 ... Integration circuit

Claims (4)

In the near magnetic field probe including the loop coil portion, the transmission line pad portion, and the signal processing portion,
A broadband near-field probe characterized in that a part of the loop coil portion is a magnetoresistive effect element made of a magnetic metal member. 2. The broadband near-field probe according to claim 1, wherein a current is applied to the magnetoresistive element using a portion other than the magnetoresistive element of the loop coil. The loop coil having a part of the loop coil portion as a magnetoresistive effect element, the transmission line portion, and the pad portion are formed of a thin film and integrally formed on a semiconductor substrate having a signal processing circuit portion. The broadband near-field probe according to Item 2. 4. The broadband near-field probe according to claim 1, further comprising a circuit unit for integrating a signal from the loop coil.

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