JP2015125135A - Impedance measurement method and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a more accurate Q value by eliminating the effect of a contact resistance component due to a measurement-use contact terminal in measuring the impedance of an element to be measured by 2-terminal measurement and obtaining a Q value from the effective-value component and reactance component of the measured impedance.SOLUTION: In obtaining a Q value which is a ratio between the effective-resistance value and reactance value of an element to be measured that includes an inductance component, a first direct-current resistance value Rdc4 of the element to be measured is measured by 4-terminal measurement, and a second direct-current resistance value Rdc2 of the element to be measured is measured by 2-terminal measurement, with an effective-resistance value Rs and an inductance value L also measured. A contact resistance Rc of a contact terminal at the time of 2-terminal measurement is calculated from a difference between the first direct-current resistance value Rdc4 and the second direct-current resistance value Rdc2 (Rdc2-Rdc4). The contact resistance Rc is subtracted from the effective-resistance value Rs (Rs-Rc) to calculate a corrected effective-resistance value Rs', and the Q value (=ωL/Rs') of the element to be measured is obtained from the corrected effective-resistance value Rs' and the inductance value L.

Description

  The present invention relates to an impedance measuring method and apparatus for measuring a Q value that is a ratio of an effective resistance value and a reactance value of a device under test, and more specifically, eliminates the influence of contact resistance of a contact terminal used for measurement. Thus, the present invention relates to a technique for obtaining a more accurate Q value.

  Usually, an LCR meter is used to measure the impedance of the device under test. The impedance Z of the device under test is expressed as Z = Rs + jX, where Rs is the effective resistance component and X is the reactance component, and the Q value is Q = X / Rs. In the case of inductance measurement, Z = Rs + jωL, and Q = ωL / Rs (ω: angular frequency).

  In Patent Document 1, in order to remove an error due to nonlinearity of a network at the time of high frequency measurement, calibration is performed using a reference device LOAD1 having a known impedance of a coaxial structure and a reference device LOAD2 having a known phase angle. It has been proposed to measure Q accuracy (phase accuracy) with high accuracy.

JP-A-7-198766

  However, in a high-frequency LCR meter having a coaxial structure and two-terminal measurement, the contact resistance component due to contact between the element to be measured and the contact terminal (fixture or probe pin) is included in the measurement value. Even if the accuracy is increased, the Q value becomes unstable due to the contact resistance component. This is a particular problem in an automatic inspection line that continuously selects parts.

  Therefore, the problem of the present invention is to eliminate the influence of the contact resistance component due to the measurement contact terminal when measuring the impedance of the element under measurement by two-terminal measurement and obtaining the Q value from the effective value component and the reactance component. The purpose is to obtain a more accurate Q value.

  In order to solve the above-described problem, the impedance measurement method of the present invention is an impedance measurement method for obtaining a Q value that is a ratio of an effective resistance value and a reactance value of an element to be measured including an inductance component. The first step of measuring the first DC resistance value Rdc4 of the measuring element and the two-terminal measurement measure the effective resistance value Rs and the inductance value L of the measured element, and the second DC resistance value Rdc2 is measured. Two steps, a third step of calculating the contact resistance Rc of the contact terminal at the time of the two-terminal measurement from the difference (Rdc2−Rdc4) between the second DC resistance value Rdc2 and the first DC resistance value Rdc4, and the effective A fourth step of calculating the corrected effective resistance value Rs ′ by subtracting the contact resistance Rc from the resistance value Rs (Rs−Rc); 'From and the inductance value L, Q value of the measuring element (.omega.L / Rs' the correction effective resistance Rs: omega is the angular frequency) is characterized by performing a fourth step of obtaining a.

  When the element to be measured is an inductor element that is DC magnetized, for example, a cored coil, the two-terminal measurement of the second step is performed prior to the four-terminal measurement of the first step, In the two-terminal measurement in the second step, it is preferable to measure the effective resistance value Rs and the inductance value L first, and then measure the second DC resistance value Rdc2.

  The impedance measuring apparatus of the present invention is an impedance measuring apparatus having a function of obtaining a Q value that is a ratio of an effective resistance value and reactance value of an element to be measured including an inductance component. The first measuring means and the second measuring means. The first DC resistance value Rdc4 of the element to be measured is measured by four-terminal measurement by the first measuring means, and the second DC resistance value is measured by two-terminal measurement of the element to be measured by the second measuring means. Rdc2, an effective resistance value Rs, and an inductance value L are measured, and the second measuring means determines the two terminals from the difference (Rdc2-Rdc4) between the second DC resistance value Rdc2 and the first DC resistance value Rdc4. The contact resistance Rc of the contact terminal at the time of measurement is calculated, and the contact resistance Rc is subtracted from the effective resistance value Rs (Rs-Rc) to compensate. 'It is calculated, and the correction effective resistance value Rs' effective resistance value Rs from the above inductance value L, Q value of the measuring element (ωL / Rs': ω is the angular frequency) is characterized by determining the.

  According to a preferred aspect of the present invention, the second measuring means includes an LCR meter, and the second DC resistance value Rdc2, the effective resistance value Rs, and the inductance value L are measured by the LCR meter.

  According to a preferred aspect of the present invention, the first measuring means and the second measuring means are connected via a predetermined communication means, and the first DC resistance value Rdc4 from the first measuring means is It is transmitted to the second measuring means.

  As another aspect, a control unit for controlling the first measurement unit and the second measurement unit is provided, and the control unit replaces the second measurement unit with the second DC resistance value Rdc2 and the first DC resistance. The contact resistance Rc of the contact terminal at the time of the two-terminal measurement is calculated from the difference (Rdc2−Rdc4) from the value Rdc4, and the contact resistance Rc is subtracted (Rs−Rc) from the effective resistance value Rs to correct the effective value. The resistance value Rs ′ may be calculated, and the Q value (ωL / Rs ′: ω is an angular frequency) of the element to be measured may be obtained from the corrected effective resistance value Rs ′ and the inductance value L. Such an embodiment is also included in the present invention.

  The first measuring means and the second measuring means are incorporated in the selection line of the element to be measured, the first measuring means is upstream of the sorting line, and the second measuring means is the sorting line. An aspect in which the four-terminal measurement is performed first by the first measurement unit and the two-terminal measurement is performed by the second measurement unit after that is arranged downstream of the line is also included in the present invention.

  When the element to be measured is an inductor element that is DC magnetized, such as a cored coil, the second measuring means is upstream of the sorting line, and the first measuring means is downstream of the sorting line. In the two-terminal measurement by the second measuring means, the effective resistance value Rs and the inductance value L are measured first, and then the second DC resistance value Rdc2 is measured, and the second measurement is performed. Following the measurement by the means, the four-terminal measurement is preferably performed by the first measurement means.

  According to the present invention, the first DC resistance value Rdc4 of the element to be measured is measured by four-terminal measurement, the effective resistance value Rs and the inductance value L of the element to be measured are measured by two-terminal measurement, and the second DC The resistance value Rdc2 is measured, the contact resistance Rc of the contact terminal at the time of two-terminal measurement is calculated from the difference (Rdc2−Rdc4) between the second DC resistance value Rdc2 and the first DC resistance value Rdc4, and the contact resistance Rc is calculated from the effective resistance value Rs. The resistance Rc is subtracted (Rs−Rc) to calculate the corrected effective resistance value Rs ′, and the Q value of the element to be measured is calculated from the corrected effective resistance value Rs ′ and the inductance value L. It is possible to obtain a more accurate Q value by eliminating the influence of the contact resistance component due to the contact terminals for use.

  Further, the two-terminal measurement is performed prior to the four-terminal measurement. In the two-terminal measurement at that time, after measuring the effective resistance value Rs and the inductance value L of the element to be measured, the second DC resistance value of the element to be measured is measured. By measuring Rdc2, and then measuring the first DC resistance value Rdc4 of the device under test by 4-terminal measurement, the device under test is a DC magnetized inductor element such as a cored coil. In addition, the inductance value L and Q value of the element to be measured can be obtained more accurately.

The schematic diagram which shows 1st Embodiment of the impedance measuring apparatus by this invention. The flowchart for operation | movement description of the said 1st Embodiment. (A) Equivalent circuit diagram showing 4-terminal measurement method, (b) Equivalent circuit diagram showing 2-terminal measurement method. The schematic diagram which shows 2nd Embodiment of the impedance measuring apparatus by this invention. The flowchart for operation | movement description of the said 2nd Embodiment.

  Next, an embodiment of the present invention will be described with reference to FIGS. 1 to 5, but the present invention is not limited to this.

  First, referring to FIG. 1, the impedance measuring apparatus 1A according to the first embodiment includes a controller 10 as a control unit, a first measuring means 20, and a second measuring means 30, and continuously selects parts. Built in automatic inspection line.

  In this embodiment, the part to be selected (element to be measured) is an inductor element D having a coil, and the inductor element D is directed from the left side (upstream side) to the right side (downstream side) in FIG. Are sequentially flown at predetermined time intervals.

  For the first measuring means 20, a DC resistance meter based on a four-terminal measuring method is used. The second measurement means 30 is a high frequency LCR meter whose measurement frequency is 100 MHz or more, for example. The controller 10 is composed of a CPU, a microcomputer, etc., and controls the measurement trigger timing of each of the measuring means 20, 30 and selects the quality of the inductor element D.

  In the first embodiment, the first measuring means 20 is disposed on the first measurement stage (four-terminal measurement stage) on the upstream side of the automatic inspection line, and the second measuring means 30 is the second measurement on the downstream side. It is arranged on a stage (two-terminal measurement stage). The first measuring means 20 and the second measuring means 30 are connected via a predetermined communication wiring. Communication may be performed wirelessly or may be performed via the controller 10.

  With reference to the flowchart of FIG. 2 as well, in obtaining the Q value excluding the contact resistance of the inductor element D, in the first embodiment, first, in step ST201, the first measuring means 20 performs the four-terminal measurement. The DC resistance value Rdc4 of the inductor element D is measured, and in the subsequent step ST202, the measured DC resistance value Rdc4 is transmitted to the LCR meter of the second measuring means 30 through the communication wiring.

  As shown in FIG. 3A, in the four-terminal measurement, four measuring contacts, that is, two probes P1 and P4 on the current supply side and two probes P2 and P3 on the voltage detection side are used. However, since the contact resistances R2 and R3 of the probes P2 and P3 on the voltage detection side are negligibly small compared to the internal resistance RV (usually about 1 to 10 GΩ) of the voltmeter V, the influence of the contact resistances R2 and R3 is affected. An accurate DC resistance value (first DC resistance value) Rdc4 that is hardly received is measured.

  The inductor element D that has been measured by the first measuring means 20 is transported to the second measuring means 30 of the second measurement stage, and in step ST301, the DC resistance value (first value) of the inductor element D is measured by two-terminal measurement of the LCR meter. 2 DC resistance value) Rdc2 is measured. The measurement of the DC resistance value Rdc2 is also performed as a contact check.

  In subsequent step ST302, the effective resistance value Rs and the inductance value L of the inductor element D are measured by the LCR meter. The two-terminal measurement of the LCR meter performed in step ST301 is performed by the equivalent circuit shown in FIG.

  In this equivalent circuit, the internal resistance RA of the ammeter A varies depending on the range, but is usually about 1 to 10Ω, so the influence on the reading value of the voltmeter V can be almost ignored, and the resistance value of the inductor element D is When the contact resistances R1 and R4 of the probes P1 and P4 are much larger, the influence of the contact resistances R1 and R4 can be ignored.

  However, if this is not the case, the DC resistance value Rdc2 of the inductor element D based on the two-terminal measurement of the LCR meter performed in step ST301 includes the contact resistances R1 and R4 of the probes P1 and P4.

Therefore, in the first embodiment, in step ST303, the contact resistances R1, R4 by the probes P1, P4 included in the DC resistance value Rdc2 of the inductor element D measured in step ST301 are set as Rc, and the DC contact resistance is set. Rc is represented by the following formula (1),
Rc = Rdc2-Rdc4 (1)
Ask for.

Since this DC contact resistance Rc has substantially no frequency characteristic dependence, in step ST304, the corrected effective resistance value Rs ′ is calculated from the effective resistance value Rs of the inductance element D and the DC contact resistance Rc by the following equation (2). ),
Rs ′ = Rs−Rc (2)
Ask for.

Then, in the next step ST305, the Q value of the inductor element D is calculated from the corrected effective resistance value Rs ′ and the inductance value L by the following equation (3),
Q = ωL / Rs ′ (3)
(Ω is an angular frequency).

  Thereby, the Q value excluding the influence of the contact resistance Rc in the two-terminal measurement can be obtained. The Q value and preferably the inductance value L as the calculation basic data are transmitted from the second measuring means 30 to the controller 10, and the controller 10 determines the inductor element D based on the Q value and / or the inductance value L. A pass / fail judgment is made, and if it is defective (NG), a rejection signal is output to the second measuring means 30 or a sorting stage (not shown) downstream of the second measuring means 30 to reject the defective product from the inspection line.

  The DC resistance value Rdc4 measured by the first measuring means 20, the DC resistance value Rdc2, the effective resistance value Rs, and the inductance value L measured by the second measuring means 30 are given to the controller 10, respectively. The contact resistance Rc, the corrected effective resistance value Rs ′, and the Q value may be obtained.

  By the way, in the first embodiment, since the measurement is performed in the order of the first measuring means 20 → the second measuring means 30, the measured element is an inductor element D that is DC magnetized, for example, like a cored coil. In this case, the inductor element D is magnetized at the time of four-terminal measurement by the first measuring means 20, whereby the inductance value L measured by the second measuring means 30 fluctuates and the Q value is also affected by the magnetization. There is.

  Such a problem can be solved by interposing a demagnetization stage between the first measurement stage by the first measurement unit 20 and the second measurement stage by the second measurement unit 30. Since the configuration of the automatic inspection line becomes complicated, it is not preferable.

  Therefore, as shown in FIG. 4, in the impedance measuring apparatus 1B according to the second embodiment of the present invention, the arrangement of the first measuring means 20 and the second measuring means 30 in the first embodiment is switched, and the first Measurement is performed by the second measurement unit 30 as one measurement stage, and then measurement is performed by the first measurement unit 20 as a second measurement stage. Each structure of the 1st measurement means 20 and the 2nd measurement means 30 may be the same as the said 1st Embodiment.

  That is, in the second embodiment, the first measurement stage is a two-terminal measurement stage, and the second measurement stage is a four-terminal measurement stage. First, in the second measurement means 30 of the first measurement stage, 2 of the LCR meter. By the terminal measurement, the effective resistance value Rs and the inductance value L of the inductor element D (core coil) are measured, and then the DC resistance value (second DC resistance value) Rdc2 of the inductor element D is measured.

  These measured values (Rdc2, L, Rs) measured by the second measuring means 30 are stored in a memory (not shown) provided in the second measuring means 30.

  Next, the inductor element D is transported from the second measurement means 30 to the first measurement means 20 of the second measurement stage, and as a next measurement, the DC resistance value (first DC resistance value) of the inductor element D is measured by four-terminal measurement. ) Rdc4 is measured, and this DC resistance value Rdc4 is transmitted from the first measuring means 20 to the second measuring means 30.

  When receiving the DC resistance value Rdc4 from the first measuring means 20, the second measuring means 30 reads the previously measured values (Rdc2, L, Rs) of the same inductor element D from the memory, and the first embodiment described above. Similarly, after calculating the direct current contact resistance Rc (= Rdc2−Rdc4) and further calculating the corrected effective resistance value Rs ′ (= Rs−Rc), the Q value of the inductor element D is obtained by Q = ωL / Rs ′. .

  Here, the operation in the automatic inspection line of the second embodiment will be described with reference to the flowchart of FIG. When the n-th inductor element Dn is measured by the second measuring means 30, the first measuring means 20 measures the inductor element Dn-m measured by the second measuring means 30 before m. And

  In the second measuring means 30, in steps ST311 to ST315, the AC effective resistance value Rs (Dn) and the inductance value L (Dn) are first measured for the inductor element Dn by the two-terminal measurement of the LCR meter. The DC resistance value Rdc2 (Dn) is measured, and these measured values (DC resistance value Rdc2 (Dn), effective resistance value Rs (Dn), L (Dn)) are stored in the memory.

  In parallel with this, in the first measuring means 20, the DC resistance value Rdc4 (Dn-m) of the inductor element Dn-m is measured by the four-terminal measurement in steps ST211 to ST214 and transmitted to the second measuring means 30. The

  When the second measuring means 30 receives the DC resistance value Rdc4 (Dn-m) of the inductor element Dn-m in step ST321, in the subsequent step ST322, the second measuring means 30 measures the measured value by the measurement performed previously on the inductor element Dn-m ( DC resistance value Rdc2 (Dn-m), effective resistance value Rs (Dn-m), and L (Dn-m)) are read from the memory.

In step ST323, the DC contact resistance Rc (Dn-m) of the inductor element Dn-m is expressed by the following equation (1a),
Rc (Dn−m) = Rdc2 (Dn−m) −Rdc4 (Dn−m) (1a)
Calculate from

Subsequently, in step ST324, the corrected effective resistance value Rs ′ (Dn−m) of the inductor element Dn−m is expressed by the following equation (2a),
Rs ′ (Dn−m) = Rs (Dn−m) −Rc (Dn−m) (2a)
Calculate from

In step ST325, Q (Dn-m) of the inductor element Dn-m excluding the contact resistance is expressed by the following equation (3a),
Q (Dn−m) = ωL (Dn−m) / Rs ′ (Dn−m) (3a)
(Ω is an angular frequency).

  As a result, the Q value excluding the influence of the contact resistance Rc in the two-terminal measurement can be obtained as in the first embodiment. In the second embodiment, when the n-th inductor element Dn is measured by the second measurement unit 30 of the first measurement stage, the m-th previous measurement is performed by the first measurement unit 10 of the second measurement stage. The inductor element Dn-m is measured, but the variable m may be arbitrarily selected within the range of the memory capacity of the second measuring means 30.

  Further, the Q value obtained in step ST325 is transmitted from the second measuring means 30 to the controller 10 as in the first embodiment, and the controller 10 determines the quality of the inductor element D based on the Q value. If it is defective (NG), an exclusion signal is output to the first measuring means 20 or a selection stage (not shown) on the downstream side of the first measuring means 20, and the defective products are excluded from the inspection line.

  Similarly to the first embodiment, the DC resistance value Rdc2, the effective resistance value Rs, the inductance value L, and the DC resistance value Rdc4 measured by the first measuring means 20 are measured by the second measuring means 30. These values may be supplied to the controller 10, and the controller 10 may determine the contact resistance Rc, the corrected effective resistance value Rs ′, and the Q value.

  In the first and second embodiments, when the DC contact resistance Rc does not match the effective resistance at the inductance measurement frequency, the same inductor element D is measured several times in advance and the correction coefficient α is set. It is good to ask.

As an example, assuming that α times the DC contact resistance Rc is an AC effective resistance value,
Rs ′ = Rs−αRc, and therefore the following formula (4) is derived.
Rs−Rs ′ = α (Rdc2−Rdc4) (4)

  In the above formula (4), (Rs−Rs ′) on the left side represents the contact resistance of the effective resistance value, and the right side represents α times the DC contact resistance. Here, the effective resistance value when measured with a stable low contact resistance using a test fixture is the constant of Rs', and the DC resistance value measured by the four-terminal measurement is the constant of Rdc4.

The same sample (inductor element D) is measured by the second measuring means 30 for two-terminal measurement while measuring Rs and Rdc2 multiple times while recontacting the probes P1 and P4.
(DC contact resistance value, effective resistance contact resistance) = (Rdc2−Rdc4, Rs−Rs ′)
, And an approximate curve is obtained by the least square method or the like to obtain a correction coefficient α.

1A, 1B Impedance measurement device 10 Controller (control unit)
20 First measurement means (4-terminal measurement)
30 Second measuring means (2-terminal measurement)
D Element to be measured (inductor element)

Claims (8)

In an impedance measurement method for obtaining a Q value that is a ratio between an effective resistance value and a reactance value of an element to be measured including an inductance component,
A first step of measuring the first DC resistance value Rdc4 of the device under test by four-terminal measurement;
A second step of measuring an effective resistance value Rs and an inductance value L of the element under measurement by a two-terminal measurement, and a second DC resistance value Rdc2;
A third step of calculating a contact resistance Rc of the contact terminal during the two-terminal measurement from a difference (Rdc2-Rdc4) between the second DC resistance value Rdc2 and the first DC resistance value Rdc4;
A fourth step of subtracting the contact resistance Rc from the effective resistance value Rs (Rs−Rc) to calculate a corrected effective resistance value Rs ′;
A fourth step of obtaining a Q value (ωL / Rs ′: ω is an angular frequency) of the device under test from the corrected effective resistance value Rs ′ and the inductance value L;
An impedance measurement method comprising:   Prior to the four-terminal measurement of the first step, the two-terminal measurement of the second step is performed. In the two-terminal measurement of the second step, the effective resistance value Rs and the inductance value L are first set. The impedance measuring method according to claim 1, wherein the second DC resistance value Rdc2 is measured after the measurement. In an impedance measuring apparatus having a function of obtaining a Q value that is a ratio between an effective resistance value and reactance value of an element to be measured including an inductance component,
A first measuring means and a second measuring means, wherein the first measuring means measures the first DC resistance value Rdc4 of the device under test by four-terminal measurement;
The second measuring means measures the second DC resistance value Rdc2, the effective resistance value Rs, and the inductance value L by the two-terminal measurement for the element to be measured.
The second measuring means calculates the contact resistance Rc of the contact terminal at the time of the two-terminal measurement from the difference (Rdc2-Rdc4) between the second DC resistance value Rdc2 and the first DC resistance value Rdc4, and the effective The contact resistance Rc is subtracted from the resistance value Rs (Rs−Rc) to calculate a corrected effective resistance value Rs ′. From the corrected effective resistance value Rs ′ and the inductance value L, the Q value of the element to be measured is calculated. (ΩL / Rs ′: ω is an angular frequency).   The LCR meter is included in the second measuring means, and the second DC resistance value Rdc2, the effective resistance value Rs, and the inductance value L are measured by the LCR meter. Impedance measuring device.   The first measuring means and the second measuring means are connected via a predetermined communication means, and the first DC resistance value Rdc4 is transmitted from the first measuring means to the second measuring means. The impedance measuring apparatus according to claim 3 or 4, characterized by the above.   A control unit for controlling the first measurement unit and the second measurement unit, wherein the control unit replaces the second measurement unit with a difference between the first DC resistance value Rdc2 and the second DC resistance value Rdc4; The contact resistance Rc of the contact terminal at the time of the two-terminal measurement is calculated from (Rdc2−Rdc4), and the contact resistance Rc is subtracted (Rs−Rc) from the effective resistance value Rs to obtain the corrected effective resistance value Rs ′. 6. The Q value (ωL / Rs ′: where ω is an angular frequency) of the element to be measured is calculated and calculated from the corrected effective resistance value Rs ′ and the inductance value L. The impedance measuring device according to claim 1.   The first measuring means and the second measuring means are incorporated in the selection line of the element to be measured, the first measuring means is upstream of the selection line, and the second measurement means is the selection line. 7. The apparatus according to claim 3, wherein the four-terminal measurement by the first measuring means is performed first, and the two-terminal measurement by the second measuring means is subsequently performed. The impedance measuring device according to any one of the above.   The first measuring means and the second measuring means are incorporated in the selection line of the element to be measured, the second measuring means is upstream of the sorting line, and the first measuring means is the sorting line. In the two-terminal measurement, which is arranged on the downstream side and is performed by the second measuring means, the effective resistance value Rs and the inductance value L are measured first, and then the second DC resistance value Rdc2 is measured. The impedance measuring apparatus according to any one of claims 3 to 6, wherein the four-terminal measurement is performed by the first measuring means following the measurement by the two measuring means.

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