JP4374572B2 - Common mode choke coil selection method - Google Patents

Description

  The present invention relates to a common mode choke coil selection method for selecting characteristic impedance of a common mode choke coil used in a transmission signal system or the like.

Generally, a common mode choke coil has two lines, and with respect to a normal mode current flowing back and forth through the lines, the impedance is minimized by canceling out magnetic flux generated by the current flowing through the two lines, and Coil that prevents common mode noise by utilizing the fact that a large impedance is generated by the addition of magnetic flux generated in two lines for a common mode current in which the currents of two lines are in the same direction. It is a part.
Such a common mode choke coil is used in an interface unit of a personal computer, a cellular phone, or the like, and its characteristic impedance is defined by a standard. For example, the DVI (Digital Visual Interface) standard is about 100Ω, the USB (Universal Serial Bus) standard is about 90Ω, the HDMI (High Definition Multimedia Interface) standard is about 100Ω, and the IEEE (Institute of Electrical and Electronics Engineers) 1394 standard is about 110Ω. Common mode choke coils each having the following characteristic impedance are required.
Therefore, it is necessary to select whether the mass-produced common mode choke coil has a desired characteristic impedance in the production line.
As such a selection method, there is a characteristic impedance measurement method by TDR (Time Domain Reflectometry).
However, this measurement method is a so-called destructive measurement test in which the characteristic impedance is measured in a state where the common mode choke coil is soldered and mounted on the evaluation board, and thus is not suitable as a mass production product selection method. In addition, there is a method of directly measuring the characteristic impedance by bringing the measurement terminal of the TDR oscilloscope into contact with the line of the common mode choke coil. However, since the measurement value varies depending on the contact state of the measurement terminal, the selection accuracy is inferior.

Therefore, the inventor considered diverting a conventional technique for measuring the characteristic impedance of a printed wiring board to a common mode choke coil (see, for example, Patent Document 1).
FIG. 8 is a perspective view for explaining the conventional technique.
As shown in FIG. 8, this technique uses a probe 210a, 210b of a potentiometer 210 and a constant current source in a printed wiring board 100 including a wiring conductor 101 having a thickness t, an insulating material 102 having a thickness H, and a ground plane conductor 103. The width W of the wiring conductor 101 is obtained by measuring the DC resistance value of the wiring conductor 101 using the probes 211a and 211b 211. The characteristic impedance is derived from the width W of the wiring conductor 101.

JP 07-128379 A

  However, with the above-described conventional technique, the characteristic impedance of the printed wiring board 100 can be measured on the assumption that the thickness t of the wiring conductor 101 and the thickness H of the insulating material 102 are known and uniform. is there. Therefore, in practice, the thickness t of the wiring conductor 101 and the thickness H of the insulating material 102 are constant regardless of the position on the printed wiring board 100, and the ground plane conductor 103 is provided on the entire surface of the printed wiring board 100. It is a prerequisite. However, in an actual product, these conditions are not always satisfied. That is, the common mode choke coil has not only the microstrip type common mode choke coil shown in FIG. 8 but also a wire wound type common mode choke coil. It is impossible to easily and quickly select characteristic impedances of a large number of common mode choke coils.

  The present invention has been made to solve the above-described problems, and provides a common mode choke coil selection method capable of easily and quickly selecting characteristic impedances of mass-produced common mode choke coils in a non-destructive manner. The purpose is to do.

In order to solve the above-mentioned problem, a common mode choke coil selection method according to the invention of claim 1 is characterized in that a common mode choke coil having a known characteristic impedance has a plurality of lines other than one line except for one line. Sorting table creation process for creating a sorting table showing a correlation between the inductance value of one line obtained through a signal of a predetermined frequency through one line and a known characteristic impedance value with both ends short-circuited, and a selection target Inductance value of one line through a short-circuit process of short-circuiting both ends of the common mode choke coil other than one line of the common mode choke coil and a signal of a predetermined frequency through one line of the common mode choke coil to be selected Inductance measurement process to measure the measured inductance value obtained in the inductance measurement process Coil selection that compares the characteristic impedance value of the selection table and selects the common mode choke coil to be selected as having the desired characteristic impedance value when the corresponding characteristic impedance value substantially matches the desired characteristic impedance value And a process.
With this configuration, in the selection table creation process, a selection table showing the correlation between the inductance value of one line in the common mode choke coil whose characteristic impedance value is known and the known characteristic impedance value is created. Then, both ends of each line other than one line of the common mode choke coil to be selected are short-circuited by the short circuit process, and the inductance value of one line of the common mode choke coil to be selected is measured by the inductance measurement process. Is done. After that, when the coil selection process compares the measured inductance value obtained in the inductance measurement process with the characteristic impedance value in the selection table, and the corresponding characteristic impedance value substantially matches the desired characteristic impedance value, the selection target Common mode choke coils are selected as having a desired characteristic impedance value.

The common mode choke coil selection method according to the invention of claim 2 is a state in which both ends of other lines except one line are short-circuited among a plurality of lines of a common mode choke coil having a known characteristic impedance. A selection table preparation process for generating a selection table showing a correlation between the inductance value of the one line obtained through a signal of a predetermined frequency in the one line and a known characteristic impedance value, and a desired table based on the selection table The permissible inductance range specifying process for specifying the inductance value range corresponding to the characteristic impedance value range, the short-circuiting process for short-circuiting both ends of the common mode choke coil line other than one of the lines to be selected, and the selection process A signal of a predetermined frequency is passed through one line of the target common mode choke coil. When the inductance measurement process for measuring the inductance value of the line of the line and the inductance value of the selection target measured in the inductance measurement process are within the range of the inductance value specified in the allowable inductance range specification process, the common mode of the selection target The choke coil is configured to include a coil selection process for selecting as having a desired characteristic impedance value.
With this configuration, in the selection table creation process, a selection table showing the correlation between the inductance value of one line in the common mode choke coil with a known characteristic impedance value and the known characteristic impedance value is created, and the allowable inductance range identification process In step (b), an inductance value range corresponding to a desired characteristic impedance value range is specified based on the selection table. Then, both ends of each line other than one line of the common mode choke coil to be selected are short-circuited by the short circuit process, and the inductance value of one line of the common mode choke coil to be selected is measured by the inductance measurement process. Is done. Then, in the coil selection process, it is determined whether the inductance value of the selection target measured in the inductance measurement process is within the range of the inductance value specified in the allowable inductance range specification process. The target common mode choke coil is selected as having the desired characteristic impedance value.

  According to a third aspect of the present invention, in the common mode choke coil selection method according to the first or second aspect, the common mode choke coil has two lines.

  Furthermore, the invention of claim 4 is the common mode choke coil selection method according to any one of claims 1 to 3, wherein the selection table creation step creates a plurality of selection tables for a plurality of different types of frequencies. It was set as the structure which is.

  According to a fifth aspect of the present invention, in the common mode choke coil sorting method according to any one of the first to fourth aspects, the common mode choke coil line is an insulation coated conductor.

  According to a sixth aspect of the present invention, in the common mode choke coil selection method according to any one of the first to fourth aspects, the common mode choke coil line is constituted by parallel plate electrodes.

  As described above, according to the common mode choke coil selection method of the present invention, both ends of a line other than one line of the common mode choke coil to be selected are short-circuited in the short-circuit process, and the selection is performed in the inductance measurement process. Since the characteristic impedance of the common mode choke coil can be selected by measuring the inductance value of one line of the target common mode choke coil, the common mode choke coil is soldered to the evaluation board as in the above TDR. As a result, there is an excellent effect that a large number of common mode choke coils can be easily selected without destruction. Further, as in the prior art shown in FIG. 8, even if the thickness t of the wiring conductor and the thickness H of the insulating material 102 are not known or uniform, the common mode choke coils are quickly selected. Work can be done.

  The best mode of the present invention will be described below with reference to the drawings.

FIG. 1 is a flowchart showing a common mode choke coil selection method according to a first embodiment of the present invention, and FIG. 2 is a perspective view of a common mode choke coil applied to the common mode choke coil selection method of this embodiment. It is.
As shown in FIG. 1, the common mode choke coil selection method of this embodiment includes a selection table creation process S1, a short circuit process S2, an inductance measurement process S3, and a coil selection process S4.

The common mode choke coil applied to the common mode choke coil selection method having such a configuration is the coil 1 shown in FIG.
This coil 1 is a winding type common mode choke coil, and windings 11 and 12 which are insulation coated conductors as two lines are wound around a core member 10, and both ends of the windings 11 and 12 are connected to the core member 10. The input electrodes 13a and 13b and the output electrodes 14a and 14b respectively provided on the flanges 13 and 14 at both ends of the structure are connected. Specifically, both ends of the winding 11 as one line are connected to the input electrode 13a and the output electrode 14a, and both ends of the winding 12 as another line are connected to the input electrode 13b and the output electrode 14b. .

The selection table creation process S1 is a process of creating a selection table D indicating the correlation between the inductance value Ls of the winding 11 and the characteristic impedance value Z in the coil 1 whose characteristic impedance value Z is known. The inductance value Ls is an inductance value of the winding 11 measured in a state where the winding 12 of the coil 1 is short-circuited.
FIG. 3 is a diagram showing an example of the sorting table D. As shown in FIG.
This sorting table D shows the correlation between the inductance value Ls of the winding 11 and the characteristic impedance value Z for the coil 1 having two different types of turns (common mode impedance value Zc is 90Ω and 67Ω, respectively).
Here, with respect to the coil 1 having a common mode impedance value Zc of 90Ω, a signal having a frequency of 100 MHz is passed through the winding 11 in a state where the winding 12 is short-circuited, and the inductance value Ls of the winding 11 measured at that time is known. A correlation line A representing the correlation of the characteristic impedance value Z is created. Specifically, it is assumed that the characteristic impedance value Z is about 63Ω when the interval between the windings 11 and 12 of the coil 1 is narrowed until the windings 11 and 12 contact each other. Then, when the inductance value Ls of the winding 11 in the coil 1 having such a structure is measured and is about 6.7 nH, the point P1 of the correlation line A is plotted. Thereafter, the inductance value Ls of the winding 11 is measured and plotted while increasing the interval between the windings 11 and 12. Then, when the inductance value Ls is measured for the winding 11 of the coil 1 having the characteristic impedance value Z of about 118Ω by extending the interval between the windings 11 and 12 to the limit, and when it is about 13.1 nH, The point P2 of the correlation line A is plotted. By continuing the plots obtained in this way, the correlation line A for the coil 1 having a common mode impedance value Zc of 90Ω can be obtained.
Similarly, a correlation line B is obtained for the coil 1 having a common mode impedance Zc of 67Ω.
In this way, after creating the sorting table D on which the correlation lines A and B are drawn, the sorting steps S2 to S5 for the coil 1 that is the sorting target are repeated.

The short circuit process S2 is a process of short-circuiting both ends of the winding 12 of the coil 1 as a selection target.
FIG. 4 is a schematic diagram for explaining the short-circuit process S2 and the inductance measurement process S3.
That is, as shown in FIG. 4, the short-circuit process S2 can be executed by short-circuiting the input electrodes 13b and 14b to which both ends of the winding 12 are connected using an appropriate conductor.

The inductance measurement process S3 is a process for measuring the inductance value of the winding 11 as a selection target. Specifically, as shown in FIG. 4, the input electrodes 13a and 14a of the winding 11 are connected to the impedance analyzer 2. The signal S having a frequency of 100 MHz is passed through the winding 11 and the inductance value of the winding 11 is measured.
Of course, the device for measuring the inductance value is not limited to the impedance analyzer, but may be another device capable of measuring the inductance value, such as a network analyzer.

The coil selection process S4 compares the measurement result obtained in the inductance measurement process S3 with the characteristic impedance value Z of the correlation line A (or correlation line B) of the selection table D, and the corresponding characteristic impedance value Z is a desired characteristic impedance. When the values substantially coincide with each other, the coil 1 measured in the inductance measurement process S3 is a process of selecting as having a desired characteristic impedance value.
For example, when selecting whether the characteristic impedance value is a 100Ω common mode choke coil, the inductance value measured in the inductance measurement process S3 corresponds to any characteristic impedance value Z in the selection table D shown in FIG. Make sure that
That is, when the measurement result that the inductance value of the winding 11 of the coil 1 whose selection target common mode impedance value Zc is 90Ω is 11 nH is obtained, the inductance value is 11 nH on the correlation line A of the selection table D. Look at the corresponding characteristic impedance value Z. Then, this characteristic impedance value Z can be confirmed to be about 100Ω. Therefore, since this characteristic impedance value Z substantially matches the desired characteristic impedance value, the selection target coil 1 is selected as a common mode choke coil having a characteristic impedance value of 100Ω.
Further, when selecting a coil conforming to the HDMI standard, the characteristic impedance value Z of ± 15% of 100Ω is required in the HDMI standard, so that the characteristic impedance value Z is 85Ω as shown by the broken line in the selection table D. Selection is based on whether or not the coil 1 has a characteristic impedance value within ˜115Ω. In such a case, it is confirmed whether or not the characteristic impedance value Z on the correlation line A corresponding to the measured inductance value is within 85Ω to 115Ω. That is, if the measured inductance value is within about 9.25 nH to about 12.7 nH, the coil 1 is selected as a coil that conforms to the HDMI standard.
Further, when selecting whether or not the coil 1 having the common mode impedance value Zc of 67Ω is a coil conforming to the HDMI standard, the correlation line B is a confirmation target, and the correlation line B on the correlation line B corresponding to the measured inductance value is selected. It is confirmed whether or not the characteristic impedance value Z is within 85Ω to 115Ω. That is, the coil 1 having a measured inductance value within about 6.5 nH to about 9.3 nH is selected as a coil that conforms to the HDMI standard.

Next, an example of selecting a large number of coils 1 using the common mode choke coil selecting method of this embodiment will be described.
FIG. 5 is a schematic view showing a measuring apparatus applied to this common mode choke coil selection method.
As shown in FIG. 5, this measuring apparatus has current-carrying terminal portions 3, 4 drawn from the impedance analyzer 2 and short-circuiting terminal portions 5, 6. These terminal portions 3 to 6 are fixed, and the terminal portions 5 and 6 are short-circuited by the conductor 7. When the coil 1 is placed on the terminal portions 3 to 6, the input electrode 13 a and the output electrode 14 a are connected to the terminal portion 3. 4, the input electrode 13 b and the output electrode 14 b are in contact with the terminal portions 5 and 6. Therefore, since the coil 1 is not fixed, the measurement can be performed only by placing the coil 1 on the terminal portions 3 to 6, and the coil 1 can be easily taken out from the terminal portions 3 to 6 after the measurement.

The sorting measurer executes the sorting table creation process S1 to create the sorting table D shown in FIG. 3 in advance, and the data of the sorting table D is automatically measured and sorted by the measuring apparatus shown in FIG. (Not shown). Then, the coil 1 as a product flowing in the mass production line is guided onto the terminal portions 3 to 6 shown in FIG.
Thereby, since the short-circuited terminal portions 5 and 6 are in contact with the input electrode 13b and the output electrode 14b of the coil 1, the short-circuit processing step S2 is automatically executed.
Further, since the terminal portions 3 and 4 are in contact with the input electrode 13a and the output electrode 14a of the coil 1, the inductance measurement process S3 can be executed by the impedance analyzer 2 of the measuring device included in the automatic measurement sorter. it can.
Here, a signal S having a frequency of 100 MHz is supplied to the winding 11 of the coil 1 from the terminal portion 3, and the inductance value of the winding 11 is measured by the impedance analyzer 2.

Thereafter, when selecting whether the coil 1 having the common mode impedance value Zc of 90Ω is the HDMI standard compliant product, the inductance value measured by the impedance analyzer 2 is about the inductance value Ls in the correlation line A of the selection table D. It is determined whether it is within 9.25 nH to about 12.7 nH. For the coil 1 having a common mode impedance value Zc of 67Ω, it is determined whether or not the measured inductance value is within about 6.5 nH to about 9.3 nH of the inductance value Ls in the correlation line B. If the measured inductance value of the coil 1 is within these ranges, the selection target coil 1 is selected as being an HDMI standard compliant product.
Then, after such sorting, the coil 1 is taken out from the terminal portions 3 to 6 by the automatic measurement sorting machine, and another coil 1 is guided onto the terminal portions 3 to 6, and the same applies to this other coil 1. Is automatically measured.
Thus, according to the common mode choke coil sorting method of this embodiment, the coils 1 can be sorted very easily, so that a large number of coils 1 can be sorted easily and quickly. In addition, since the characteristic impedance value can be selected simply by bringing the coil 1 into contact with the terminal portions 3 to 6 without soldering, the coil 1 can be selected in a non-destructive manner. Excellent as a method. In addition, since it is not necessary to measure the thickness of each member of the coil 1 in advance, it is possible to speed up the sorting operation accordingly. Furthermore, since only the inductance value of the winding 11 is measured, there is almost no variation in measurement, and high-precision sorting is possible.

Next, a common mode choke coil selection method according to a second embodiment of the present invention will be described.
FIG. 6 is a flowchart showing a common mode choke coil selection method according to the second embodiment of the present invention.
As shown in FIG. 6, in this embodiment, an allowable inductance range specifying step S10 is provided after the selection table creation step S1, and a coil selection step S40 different from the coil selection step S4 of the first embodiment is used as the coil selection step. Is different from the first embodiment.

The allowable inductance range specifying step S10 is a step of specifying an inductance value range corresponding to a desired characteristic impedance value range based on the selection table D created in the selection table creation step S1.
That is, for a common mode choke coil having a characteristic impedance value of 100Ω, for example, in the HDMI standard, a characteristic impedance value Z of ± 15% of 100Ω is regarded as a conforming product. Therefore, as shown in FIG. Is 85Ω to 115Ω.
Therefore, in the common mode choke coil having a common mode impedance value Zc of 90Ω, the range of the inductance value Ls corresponding to the range of the characteristic impedance value is within the range of the intersection of the correlation line A and the broken line, and is about 9.25 nH. To about 12.7 nH. In the common mode choke coil having a common mode impedance value Zc of 67Ω, the range of the inductance value Ls corresponding to the range of the characteristic impedance value is the range of the intersection of the correlation line B and the broken line, and is about 6.5 nH. To about 9.3 nH.
Therefore, in the allowable inductance range specifying step S10, as shown in FIG. 3, about 9.25 nH to about 12.7 nH are specified as the range La, and about 6.5 nH to about 9.3 nH are specified as the range Lb. deep.

  The short circuit process and the inductance measurement process are the same as the short circuit process S2 and the inductance measurement process S3 of the first embodiment.

The coil selection process S40 is performed when the inductance value of the coil to be selected measured in the inductance measurement process S3 is within the range La (Lb) of the inductance value specified in the allowable inductance range specification process S10. The characteristic impedance value is a process of selecting the characteristic impedance value as being in a desired characteristic impedance value range of 85Ω to 115Ω.
Specifically, for a common mode choke coil having a common mode impedance value Zc of 90Ω, whether or not the measured inductance value is within the range La (about 9.25 nH to about 12.7 nH) shown in the selection table D. If it is within the range La, this coil is selected as a conforming product.
Further, for a common mode choke coil having a common mode impedance value Zc of 67Ω, it is determined whether or not the measured inductance value is within the range Lb (about 6.5 nH to about 9.3 nH), and is within the range Lb. In this case, the coil is selected as a compatible product.

Thus, according to this embodiment, the measured inductance value is within the specified inductance value range La (Lb) without comparing the measured inductance value of the selection target with the characteristic impedance value Z of the selection table D. Since it is possible to perform the sorting only by confirming whether or not the above is present, it is possible to further speed up the sorting operation.
Since other configurations, operations, and effects are the same as those of the first embodiment, description thereof is omitted.

In addition, this invention is not limited to the said Example, A various deformation | transformation and change are possible within the range of the summary of invention.
In the first embodiment, the selection table D corresponding to the frequency of 100 MHz is created in order to select the coil 1 using the signal of the frequency of 100 MHz. However, when the coil 1 is selected using the signal of the other frequency. The sorting table D corresponding to the other frequency may be created. In a common mode choke coil used for a cellular phone or the like, it is preferable to prepare a sorting table D corresponding to a signal having a frequency of 100 MHz to 1 GHz. In addition, the target coil of the sorting table D is not limited to the coil 1 having the common mode impedance value Zc of 67Ω and 90Ω. A coil having various common mode impedance values Zc corresponding to the number of turns can be the target of the sorting table D.

  In the above-described embodiment, the coil 1 having the windings 11 and 12 that are two lines is applied as a selection target. However, the present invention can also be applied to a common mode choke coil having three or more lines. . For example, as shown in FIG. 7, in a common mode choke coil having windings 11, 12-1, and 12-2 that are three lines, as shown in FIG. 12-2 can be short-circuited, or as shown in FIG. 7B, the inductance value Ls of the winding 11 can be measured in a state where the windings 12-1 and 12-2 are short-circuited together. it can.

  Further, in the above-described embodiment, the present invention is applied to the winding type coil 1, but the present invention can also be applied to a coil in which a line is constituted by parallel plate electrodes. That is, it is needless to say that the present invention can also be applied to a transmission line type common mode choke coil composed of two or more flat, straight, meander or spiral lines.

It is a flowchart which shows the common mode choke coil selection method based on 1st Example of this invention. It is a perspective view of the common mode choke coil applied to the common mode choke coil selection method of the first embodiment. It is a diagram which shows an example of the selection table | surface applied to the common mode choke coil selection method of 1st Example. It is the schematic for demonstrating a short circuit process and an inductance measurement process. It is the schematic which shows the measuring apparatus applied to the common mode choke coil selection method. It is a flowchart which shows the common mode choke coil selection method based on 2nd Example of this invention. It is a schematic circuit diagram which shows a modification. It is a perspective view for demonstrating the prior art.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Coil, 2 ... Impedance analyzer, 3, ..., 6 ... Terminal part, 10 ... Core member, 11, 12 ... Winding, 13, 14 ... Saddle, 13a, 13b ... Input electrode, 14a, 14b ... Output electrode A, B ... correlation line, La, Lb ... inductance range, S ... signal.

Claims (6)

Among the plurality of lines of a common mode choke coil having a known characteristic impedance, the one line obtained by passing a signal of a predetermined frequency through the one line with both ends of the other lines except one line short-circuited. A sorting table creation process for creating a sorting table showing a correlation between the inductance value of the line and the known characteristic impedance value;
A short-circuit process for short-circuiting both ends of lines other than one of the lines of the common mode choke coil to be selected;
An inductance measurement process for measuring an inductance value of the one line through a signal of the predetermined frequency to the one line of the common mode choke coil to be selected;
When the measured inductance value obtained in the inductance measurement process is compared with the characteristic impedance value of the selection table, and the corresponding characteristic impedance value substantially matches the desired characteristic impedance value, the common mode choke coil to be selected is A coil sorting process for sorting as having the desired characteristic impedance value;
A method for selecting a common mode choke coil, comprising: Among the plurality of lines of a common mode choke coil having a known characteristic impedance, the one line obtained by passing a signal of a predetermined frequency through the one line with both ends of the other lines except one line short-circuited. A sorting table creation process for creating a sorting table showing a correlation between the inductance value of the line and the known characteristic impedance value;
Based on the above selection table, an allowable inductance range specifying process for specifying an inductance value range corresponding to a desired characteristic impedance value range;
A short-circuit process for short-circuiting both ends of lines other than one of the lines of the common mode choke coil to be selected;
An inductance measurement process for measuring an inductance value of the one line through a signal of the predetermined frequency to the one line of the common mode choke coil to be selected;
When the inductance value of the selection target measured in the inductance measurement process is within the range of the inductance value specified in the allowable inductance range specification process, the common mode choke coil of the selection target has the desired characteristic impedance value. A coil sorting process for sorting as having
A method for selecting a common mode choke coil, comprising: In the common mode choke coil selection method according to claim 1 or 2,
The common mode choke coil has two lines.
A common mode choke coil selection method characterized by the above. In the common mode choke coil selection method according to any one of claims 1 to 3,
The sorting table creation process creates a plurality of the sorting tables for different types of frequencies.
A common mode choke coil selection method characterized by the above. In the common mode choke coil selection method according to any one of claims 1 to 4,
The line of the common mode choke coil is an insulation coated conductor;
A common mode choke coil selection method characterized by the above. In the common mode choke coil selection method according to any one of claims 1 to 4,
The line of the common mode choke coil is composed of parallel plate electrodes.
A common mode choke coil selection method characterized by the above.

Images