Patent Grant
11965117
The present disclosure relates to a soft magnetic material powder used for a magnetic core and a manufacturing method thereof. In addition, the present disclosure also relates to a magnetic core using this soft magnetic material powder and a manufacturing method of the magnetic core.
In recent years, in concomitance with the reduction in size of electric apparatuses and electronic apparatuses, magnetic cores forming transformers and coils, which are used for the above apparatuses, are required to have characteristics, such as a high magnetic permeability and a low eddy-current loss, at a high frequency. Accordingly, in order to obtain a low eddy-current loss in a high frequency band, the magnetic core is required to have a high electric resistance. As one example of the magnetic core as described above, for example, there has been a powder magnetic core formed in such a way that after a magnetic material is formed into a fine particulate powder, the surface of each particle is covered with an insulating film, and the particles thus treated are processed by compression molding. Compared to the case in which a bulky magnetic material is used, by the powder magnetic core, although the magnetic permeability is decreased, in particular, the electric resistance can be significantly increased, and the eddy-current loss can be remarkably decreased.
Heretofore, a method has been known in which after hydroxides are adsorbed on the surface of pure Fe which is a magnetic material powder by hydrolysis of a metal alkoxide, a sintered body is obtained by pressing the powder thus obtained (for example, see Japanese Unexamined Patent Application Publication No. 09-125111).
In addition, a manufacturing method to obtain a molded powder compact has been known (for example, see Japanese Unexamined Patent Application Publication No. 2012-172172). In this method, after a compaction molding powder in which a metal alkoxide and a mineral containing crystal water are present on surfaces of soft magnetic metal particles and this compaction molding powder are compressed to form a green molded body, this green molded body is annealed to hydrolyze the metal alkoxide and to generate insulating films on the surfaces of the soft magnetic metal particles.
The magnetic material powder disclosed in Japanese Unexamined Patent Application Publication No. 09-125111 has a good insulating property, and a thin inorganic film is formed on the surface of the metal magnetic powder. On the other hand, the fluidity in powder compaction molding is inferior, and the magnetic permeability of the powder magnetic core is not increased, and furthermore, there have been problems in that fine cracks are generated in the organic films in powder compaction molding, the electric resistance is decreased in annealing, and the eddy-current loss is increased.
Since the molded powder compact disclosed in Japanese Unexamined Patent Application Publication No. 2012-172172 has a high film strength of the insulating film, no cracks are generated in powder compaction molding, and the electric resistance is not decreased in annealing. However, there have been problems in that since the mineral is added, a thin film cannot be formed, the density of a magnetic powder of the powder magnetic core is not increased, and as a result, the magnetic permeability is not sufficiently increased.
The present disclosure aims to provide a soft magnetic material powder capable of obtaining a magnetic core having a sufficient density, a high magnetic permeability, and also a high electric resistance.
A soft magnetic material powder according to the present disclosure comprises:
According to the soft magnetic material powder of the present disclosure, when a magnetic core is molded therefrom, as the soft magnetic material, a sufficient density can be obtained, and the magnetic permeability of the magnetic core can be increased. In addition, by the insulating film and a binder of each soft magnetic material particle contained in the soft magnetic material powder, a magnetic core having a high electric resistance can be obtained.
A soft magnetic material powder according to a first aspect comprises:
In a soft magnetic material powder according to a second aspect, the water soluble polymer described in the above first aspect may be at least one selected from the group consisting of a poly(vinyl pyrrolidone), a poly(ethylene imine), a carboxymethyl cellulose, a gelatin, a poly(acrylic acid), a poly(ethylene glycol), and a poly(vinyl alcohol).
In a soft magnetic material powder according to a third aspect, the water soluble polymer described in the above first aspect is a poly(vinyl pyrrolidone) and may be contained in a range of 0.01 to 1 percent by weight.
In a soft magnetic material powder according to a fourth aspect, wherein the inorganic oxide described in any one of the above first to third aspects may be at least one selected from the group consisting of TiO2, SiO2, Al2O3, and ZrO. The inorganic oxide may also be a polysiloxane.
In a soft magnetic material powder according to a fifth aspect, the inorganic oxide described in any one of the above first to third aspects is SiO2 and may be contained in a range of 0.01 to 5 percent by weight.
In a soft magnetic material powder according to a sixth aspect, the Fe-based soft magnetic material described in any one of the above first to fifth aspects may be at least one selected from the group consisting of Fe, FeNi, FeCo, FeSi, FeSiCr, FeSiAl, and FeSiBCr.
A method for manufacturing a soft magnetic material powder according to a seventh aspect comprises:
dispersing an Fe-based soft magnetic material in a solvent; and
adding a metal alkoxide and a water soluble polymer to the solvent to hydrolyze the metal alkoxide and to form insulating films each containing a metal oxide, which is a hydrolysate of the metal alkoxide, and the water soluble polymer on surfaces of soft magnetic material particles which form the Fe-based soft magnetic material powder, so that an insulating treatment is performed on the soft magnetic material particles.
A magnetic core according to an eighth aspect comprises the soft magnetic material powder according to any one of the above first to sixth aspects.
A magnetic core according to a ninth aspect is a magnetic core which comprises:
A magnetic core according to a tenth aspect is a magnetic core which comprises:
A method for manufacturing a magnetic core according to an eleventh aspect comprises:
A method for manufacturing a magnetic core according to a twelfth aspect comprises:
An electronic component according to a thirteenth aspect comprises the magnetic core according to any one of the above eighth to the tenth aspects.
Hereinafter, a soft magnetic material powder and a manufacturing method thereof and a magnetic core and a manufacturing method thereof according to embodiments will be described with reference to the attached drawings. In addition, in the drawings, substantially the same members are designated by the same reference numeral.
Soft Magnetic Material Powder
In this soft magnetic material powder, since a raw material of the insulating film 2 contains a water soluble polymer together with an inorganic oxide, a thin insulating film 2 can be obtained. Furthermore, since a flexible water soluble polymer is present in the insulating film 2, a stress generated in compression molding can be reduced, and hence, molding can be performed at a low pressure. As a result, even in compression molding for manufacturing of a magnetic core, no cracks are generated in the insulating film 2 of the soft magnetic material particle included in the soft magnetic material powder. That is, according to this soft magnetic material powder, excellent compression moldability can be obtained.
The average particle diameter of the core 1 containing the Fe-based soft magnetic material of the soft magnetic material particle 10, which forms this soft magnetic material powder, is, for example, in a range of 0.1 to 100 μm. The thickness of the insulating film 2 of the soft magnetic material particle 10 is, for example, in a range of 5 to 100 nm and preferably in a range of 20 to 40 nm. The thickness was measured by a transmission electron microscope (TEM). In particular, by the use of a thin sample obtained by processing a magnetic core, the thickness of the insulating film 2 was measured at 5 locations of each of 5 viewing fields of the observation image by a transmission electron microscope at a magnification of 100,000 to 200,000 times, and the average value obtained therefrom was regarded as the thickness of the insulating film 2.
Hereinafter, members forming this soft magnetic material powder will be described.
Fe-Based Soft Magnetic Material: Core
As the Fe-based soft magnetic material used for the core 1, for example, Fe and an alloy containing Fe may be used. As the alloy containing Fe, for example, various Fe-based magnetic metals, such as FeNi, FeCo, FeSi, FeSiCr, FeSiAl, and FeSiBCr, which have been used in the past, may be mentioned. The soft magnetic material may further contain an impurity.
Insulating Film
The insulating film 2 contains an inorganic oxide and a water soluble polymer.
Inorganic Oxide
As a metal element M forming the inorganic oxide, at least one type selected from the group consisting of Li, Na, Mg, Al, Si, K, Ca, Ti, Cu, Sr, Y, Zr, Ba, Ce, Ta, and Bi may be used. In addition, for example, in consideration of the strength and the inherent specific resistance of an oxide to be obtained, Si, Ti, Al, and Zr are preferable. This metal element M is a metal of a metal alkoxide used to form the insulating film 2. As a concrete inorganic oxide, SiO2, TiO2, Al2O3, or ZrO is preferable. SiO2 is particularly preferable.
In addition, the inorganic oxide is contained in a range of 0.01 to 5 percent by weight with respect to the soft magnetic material powder.
Water Soluble Polymer
As the water soluble polymer, at least one selected from the group consisting of a poly(ethylene imine), a poly(vinyl pyrrolidone), a poly(ethylene glycol), a sodium polyacrylate, a carboxymethyl cellulose, a poly(vinyl alcohol), and a gelatin may be used, or at least two types thereof may be used in combination.
The water soluble polymer is contained in a range of 0.01 to 1 percent by weight with respect to the soft magnetic material powder.
Method for Manufacturing Soft Magnetic Material Powder
A method for manufacturing this soft magnetic material powder will be described.
(1) An Fe-based soft magnetic material powder is dispersed in a solvent.
(2) A metal alkoxide and a water soluble polymer are added in the solvent, followed by stirring.
In this step, the metal alkoxide is hydrolyzed. On the surface of each soft magnetic material particle forming the Fe-based soft magnetic material powder, an insulating film containing a metal oxide, which is a hydrolysate of the metal alkoxide, and the water soluble polymer is formed.
By the procedure described above, a soft magnetic material powder including insulation-treated soft magnetic material particles can be obtained.
Hereinafter, a method for manufacturing this soft magnetic material powder will be described.
Fe-Based Soft Magnetic Material
The Fe-based soft magnetic material is the same as described above, and the description thereof is omitted.
Solvent
As the solvent, an alcohol, such as methanol or ethanol, may be used.
Metal Alkoxide
As a metal element M of a metal alkoxide in the form of M-OR to be added, at least one type selected from the group consisting of Li, Na, Mg, Al, Si, K, Ca, Ti, Cu, Sr, Y, Zr, Ba, Ce, Ta, and Bi may be used. In addition, for example, in consideration of the strength and the inherent specific resistance of an oxide to be obtained, Si, Ti, Al, and Zr are preferable.
In addition, as the alkoxy group OR of the metal alkoxide, an arbitrary group, such as a methoxy group, an ethoxy group, or a propoxy group, may be selected.
In addition, at least two types of metal alkoxides may be used in combination.
In order to increase a hydrolysis rate of the metal alkoxide, if needed, there may be added an acidic catalyst, such as hydrochloric acid, acetic acid, or phosphoric acid; a basic catalyst, such as ammonia, sodium hydroxide, or piperidine; or a salt catalyst, such as ammonium carbonate or ammonium acetate.
A dispersion liquid obtained after stirring may be dried by an appropriate method (oven, spray, in vacuo, or the like). A drying temperature may be, for example, in a temperature range of 50° C. to 300° C. A drying time may be appropriately determined. For example, the drying time may be, for example, in a range of 10 minutes to 24 hours.
Powder Magnetic Core
In addition, in some cases, depending on the temperature of a heat annealing treatment, some of the functional groups of the water soluble polymer may be lost from the insulating film 2, or the water soluble polymer may be partially or entirely lost by heat decomposition, evaporation, or volatilization thereof.
Since this powder magnetic core 20 is formed using a soft magnetic material powder including the soft magnetic material particles each having the thin insulating film 2, the soft magnetic materials 1 are isolated from each other with the insulating films 2 and the binder 12 provided therebetween. Hence, without generating cracks in the insulating film 2 of the soft magnetic material particle, a high electric resistance can be maintained by the insulating film 2 and the binder 12. As a result, the effect of low eddy-current loss can be obtained. In addition, since the insulating film 2 of the soft magnetic material particle 10 included in the soft magnetic material powder is thin, in the powder magnetic core 20, the thickness of the insulating film 2 can also be decreased. As a result, the density of the soft magnetic material 1 can be increased, and a high magnetic permeability can be obtained.
In addition, this magnetic core may also be used for a coil component or an electronic component, such as an inductor. In this case, in the coil component, as the magnetic core, a member around which a coil-shaped conductor is wound may be mentioned. Alternatively, in the coil component, as the magnetic core, a member in which a coil-shaped conductor is arranged may be mentioned. The coil-shaped conductor may be a wire wound in a coil form or a patterned conductor formed to have a coil shape may be mentioned.
Hereinafter, members forming this powder magnetic core will be described.
Soft Magnetic Material
The soft magnetic material 1 is substantially the same as that of the above Fe-based soft magnetic material, and the description thereof is omitted.
Insulating Film
The insulating film 2 is derived from the insulating film 2 of the soft magnetic material particle 10 included in the soft magnetic material powder. That is, the insulating film 2 contains an inorganic oxide and a water soluble polymer. However, the insulating film 2 of the magnetic core (hereinafter, referred to as “annealed magnetic core” in some cases) formed by heat annealing may contain no water soluble polymer in some cases. In addition, the inorganic oxide contained in the insulating film 2 of the annealed magnetic core may include, besides the oxide of the above metal element M, an oxide of Fe in some cases. In addition, an inorganic oxide contained in the insulating film 2 of an annealed magnetic core which uses an alloy (such as FeSiCr, FeSiBCr, or FeSiAl) containing Fe and Cr or Al as a soft magnetic material may further include, besides the oxide of the metal element M and the oxide of Fe, an oxide of Cr or an oxide of Al in some cases.
Binder The binder 12 is a binder which is added when a powder magnetic core is manufactured. The binder 12 is not particularly limited as long as a thermosetting resin is used, and for example, an epoxy resin, an imide resin, a silicone resin, or a fluorinated resin may be used. Those resins may be used alone, or at least two types thereof may be selectively used in combination. By the insulating film 2 and the binder 12 described above, the soft magnetic materials 1 are isolated from each other.
Method for Manufacturing Powder Magnetic Core
Next, a method for manufacturing a powder magnetic core will be described.
As described above, the magnetic core can be obtained. A magnetic core obtained by performing an annealing treatment at 400° C. or more is called, for example, an annealed magnetic core. On the other hand, a magnetic core which is not processed by an annealing treatment is called, for example, a heat-cured magnetic core.
According to this method for manufacturing a powder magnetic core, as described above, there is used a soft magnetic material powder comprising the soft magnetic material particles each including the core 1 which contains an Fe-based soft magnetic material and the insulating film 2 which covers the surface of the core 1 and which contains an inorganic oxide and a water soluble polymer. Since a flexible water soluble polymer is present in the insulating film 2 of the soft magnetic material particle 10, the stress generated in compression molding can be reduced, and hence, molding can be performed at a low pressure. As a result, even in powder compaction molding for manufacturing a powder magnetic core, cracks are not generated in the insulating film 2 of the soft magnetic material particle included in the soft magnetic material powder, and the insulating film 2 and the binder 12 are not broken. As a result, in this powder magnetic core, a high electric resistance can be realized, and the effect of low eddy-current loss can be obtained.
Hereinafter, with reference to Tables 1 and 2, Examples 1 to 19 and Comparative Examples 1 to 3 will be described.
Manufacturing conditions of soft magnetic material powders and powder magnetic cores are shown in Table 1, and the measurement values and the evaluation results are shown in Table 2.
Insulating Treatment of Soft Magnetic Material Powder
A method for manufacturing a soft magnetic material powder according to Example 1 will be described.
Accordingly, an insulation-treated soft magnetic material powder (on which an insulating film was formed) was obtained.
Formation and Quality Confirmation of Powder Magnetic Core Using Soft Magnetic Material Powder
Next, the formation of a powder magnetic core using the insulation-treated soft magnetic material powder thus obtained will be described.
When the specific magnetic permeability obtained from the measured magnetic permeability was 30 or more, and when the specific resistance was 108 Ω·cm or more, the evaluation result was represented by ◯ (accepted), and when at least one of them was less than the value described above, the evaluation result was represented by X (rejected).
Withstand Voltage Test
From this test, it was found that in Examples 1 and 2 according to the present disclosure, a magnetic core having a high withstand voltage capable of withstanding an application voltage of 900 V could be provided.
Operation and Effect
As shown in Table 2, from the soft magnetic material powder according to Example 1, the powder magnetic core could be formed at a low molding pressure (4 t/cm2). The powder magnetic core thus obtained had a high specific magnetic permeability (39), and even after the heat annealing treatment was performed, the specific resistance was high (6.0×1011 Ω·cm). In addition, from the results obtained from the line analysis shown in
From this analysis result, in comparison between Example 1 and Comparative Example 1, it is believed that since a large amount of Si is contained in the insulating film 2 as compared to that of Cr, a magnetic core having a high withstand voltage can be obtained.
Except that as shown in Table 1, the addition amount of the tetraethyl orthosilicate used as the metal alkoxide was changed (Example 2: 0.01 percent by weight, Example 3: 5 percent by weight), a soft magnetic material powder and a powder magnetic core were formed in a manner similar to that of Example 1, and the measurement and the evaluation were performed.
Operation and Effect
As shown in Table 2, as was the case of Example 1, the powder magnetic core could be formed at a low molding pressure (4 t/cm2). In addition, the powder magnetic core thus obtained had a high specific magnetic permeability (Example 2: 39, Example 3: 39), and even after the heat annealing treatment was performed, the specific resistance was high (Example 2: 1.0×1011 Ω·cm, Example 3: 3.5×1011 Ω·cm).
Except that as shown in Table 1, the addition amount of the poly(vinyl pyrrolidone) used as the water soluble polymer was changed (Example 4: 0.01 percent by weight, Example 5: 1 percent by weight), a soft magnetic material powder and a powder magnetic core were formed in a manner similar to that of Example 1, and the measurement and the evaluation were performed.
Operation and Effect
As shown in Table 2, as was the case of Example 1, the powder magnetic core could be formed at a low molding pressure (4 t/cm2). In addition, the powder magnetic core thus obtained had a high specific magnetic permeability (Example 4: 37, Example 5: 33), and even after the heat annealing treatment was performed, the specific resistance was high (Example 4: 1.8×1011 Ω·cm, Example 5: 4.3×1011 Ω·cm).
Except that as shown in Table 1, the type of water soluble polymer to be used was changed (Example 6: poly(ethylene imine), Example 7: carboxymethyl cellulose, Example 8: gelatin, Example 9: poly(acrylic acid), Example 10: poly(ethylene glycol), Example 11: poly(vinyl alcohol)), a soft magnetic material powder and a powder magnetic core were formed in a manner similar to that of Example 1, and the measurement and the evaluation were performed.
Operation and Effect
As shown in Table 2, as was the case of Example 1, the powder magnetic core could be formed at a low molding pressure (4 t/cm2). In addition, the powder magnetic core thus obtained had a high specific magnetic permeability (Example 6: 35, Example 7: 36, Example 8: 38, Example 9: 36, Example 10: 35, Example 11: 37), and even after the heat annealing treatment was performed, the specific resistance was high (Example 6: 3.9×1011 Ω·cm, Example 7: 4.5×1011 Ω·cm, Example 8: 3.4×1011 Ω·cm, Example 9: 5.4×1011 Ω·cm, Example 10: 3.0×1011 Ω·cm, Example 11: 3.4×1011 Ω·cm).
Except that as shown in Table 1, the type of metal alkoxide to be used was changed (Example 12: aluminum isopropoxide, Example 13: titanium tetraisopropoxide, Example 14: zirconium-n-butoxide), a soft magnetic material powder and a powder magnetic core were formed in a manner similar to that of Example 1, and the measurement and the evaluation were performed.
Operation and Effect
As shown in Table 2, as was the case of Example 1, the powder magnetic core could be formed at a low molding pressure (4 t/cm2). In addition, the powder magnetic core thus obtained had a high specific magnetic permeability (Example 12: 37, Example 13: 38, Example 14: 36), and even after the heat annealing treatment was performed, the specific resistance was high (Example 12: 6.4×1011 Ω·cm, Example 13: 4.2×1011 Ω·cm, Example 14: 7.4×1011 Ω·cm).
Except that as shown in Table 1, the heat annealing treatment was not performed, a soft magnetic material powder and a powder magnetic core were formed in a manner similar to that of Example 1, and the measurement and the evaluation were performed.
Operation and Effect
As shown in Table 2, according to the powder magnetic core of Example 15, the formation thereof could be formed at a low molding pressure, and although the heat annealing treatment was not performed, a high specific magnetic permeability (30) and a high specific resistance (6.0×1013 Ω·cm) could be obtained.
Except that as shown in Table 1, the addition amount of the tetraethyl orthosilicate used as the metal alkoxide was changed (Example 16: 0.01 percent by weight, Example 17: 5 percent by weight), a soft magnetic material powder and a powder magnetic core were formed in a manner similar to that of Example 15, and the measurement and the evaluation were performed.
Operation and Effect
As shown in Table 2, as was the case of Example 15, the powder magnetic core could be formed at a low molding pressure, and although the heat annealing treatment was not performed, a high specific magnetic permeability (Example 16: 31, Example 17: 30) and a high specific resistance (Example 16: 5.0×1013 Ω·cm, Example 17: 4.8×1013 Ω·cm) could be obtained.
Except that as shown in Table 1, the addition amount of the poly(vinyl pyrrolidone) used as the water soluble polymer was changed (Example 18: 0.01 percent by weight, Example 19: 1 percent by weight), a soft magnetic material powder and a powder magnetic core were formed in a manner similar to that of Example 15, and the measurement and the evaluation were performed.
Operation and Effect
As shown in Table 2, as was the case of Example 15, the powder magnetic core could be formed at a low molding pressure, and although the heat annealing treatment was not performed, a high specific magnetic permeability (Example 18: 31, Example 19: 30) and a high specific resistance (Example 18: 1.9×1013 Ω·cm, Example 19: 3.8×1013 Ω·cm) could be obtained.
As shown in Table 1, in Comparative Example 1, by the use of a magnetic powder which was not processed by an insulating treatment, granulation was formed in a manner similar to that of Example 1, and a powder magnetic core was then formed at a molding pressure of 8 t/cm2 while heating was performed at 150° C.
In Comparative Example 2, except that the poly(vinyl pyrrolidone) functioning as the water soluble polymer was not added, a soft magnetic material powder and a powder magnetic core were formed in a manner similar to that of Example 1.
Operation and Effect
As shown in Tables 1 and 2, according to Comparative Example 1, although a powder magnetic core having a high specific magnetic permeability (39) could be obtained, a high molding pressure (8 t/cm2) and warm molding were required, and since the insulating treatment of the soft magnetic material powder was not performed, the specific resistance after the heat annealing treatment was decreased (1.5×105 Ω·cm).
In Comparative Example 2, a powder magnetic core having a relatively low specific magnetic permeability (20) was only obtained. In addition, in the pressure molding, fine cracks were generated in the insulating film, and the specific resistance was decreased (4.2×107 Ω·cm).
In addition, in the above examples, although FeSiCr was used as the magnetic material, the magnetic material is not limited thereto, and another Fe-based soft magnetic material may also be used. In addition, the temperature of the heat annealing treatment is not limited to 720° C., and the heat annealing treatment may be performed when the temperature is set in a range of 400° C. to 900° C. and furthermore in a range of 600° C. to 900° C.
In addition, in the present disclosure, the various embodiments described above may be arbitrarily used in combination, and the advantages of the individual embodiments may also be obtained.
According to the soft magnetic material powder of the present disclosure, as the soft magnetic material, a sufficient density and a high magnetic permeability can be obtained, and furthermore, a magnetic core having a high electric resistance and a high withstand voltage can also be obtained by the insulating films and the binder of the soft magnetic material particles included in the soft magnetic material powder, and hence, the above soft magnetic material powder is effectively used as a soft magnetic material powder for magnetic cores.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014-209308 | Oct 2014 | JP | national |
This application is Continuation of U.S. patent application Ser. No. 16/861,037 filed Apr. 28, 2020, which is a Divisional of U.S. patent application Ser. No. 15/434,488 filed Feb. 16, 2017, which claims benefit of priority to Japanese Patent Application 2014-209308 filed Oct. 10, 2014, and to International Patent Application No. PCT/JP2015/075945 filed Sep. 14, 2015, the entire content of which is incorporated herein by reference.
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|---|---|---|---|
| 10825590 | Ishida | Nov 2020 | B2 |
| 20110156850 | Okamoto et al. | Jun 2011 | A1 |
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| 1613919 | May 2005 | CN |
| 102360665 | Feb 2012 | CN |
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| 102623125 | Aug 2012 | CN |
| 103943296 | Jul 2014 | CN |
| H09-125111 | May 1997 | JP |
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| International Search Report issued in PCT/JP2015/075945; dated Dec. 1, 2015. |
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| Notification of the First Office Action issued by the State Intellectual Property Office of the People's Republic of China on Oct. 31, 2017, which corresponds to Chinese U.S. Appl. No. 15/434,488.8 and is related to U.S. Appl. No. 15/434,488. |
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| Number | Date | Country | |
|---|---|---|---|
| 20210054218 A1 | Feb 2021 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15434488 | Feb 2017 | US |
| Child | 16861037 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 16861037 | Apr 2020 | US |
| Child | 17087146 | US | |
| Parent | PCT/JP2015/075945 | Sep 2015 | US |
| Child | 15434488 | US |
