JPH05275247A - Thin inductor/transformer - Google Patents

Abstract

PURPOSE:To raise an inductance and to reduce a temperature rise in a thin inductor/transformer which is formed by piling up a spiral plane coil, an insulating film and a magnetic film on an insulating substrate. CONSTITUTION:An oxide soft magnetic material of large permeability and saturation density is applied to an insulating substrate 1 and/or insulating films 4a, 4b. An oxide soft magnetic material of high electric resistance and small power loss is used for magnetic films 5a, 5b. Since magnetic resistance thereby lowers and magnetic flux density rises in an area near a central part and an area near an outermost side part of spiral plane coils 2a, 2b, an inductance rises. Furthermore, heat generation due to eddy current loss at high frequency is reduced and a temperature rise is reduced by using the oxide soft magnetic material for the magnetic films 5a, 5b instead of a metallic soft magnetic material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin inductor / transformer used as a component of a power supply or a signal processing circuit.

[0002]

2. Description of the Related Art In response to the demand for smaller and thinner electronic equipment, smaller and thinner magnetic parts such as inductors and transformers used for power supply and signal processing are being advanced.

A winding type inductor / transformer in which a winding is applied to a sintered ferrite core has a limit in miniaturization, and research into a method of using a plane coil instead of the winding is underway. Various thin inductors and transformers that combine an insulating film and a magnetic film have been proposed. These thin inductors and transformers are roughly classified into an internal coil type in which the planar coil is surrounded by the magnetic film and an external coil type in which the magnetic film is surrounded by the planar coil, depending on the combination of the magnetic film and the planar coil. A transformer can be obtained by providing a plurality of plane coils.

The shape of the plane coil is a spiral shape or a zigzag shape as a typical shape for the inner coil shape. Also, for the external coil type, there are a cross type, a wound type and the like. These thin inductors / transformers are formed on an insulating substrate. As an example of a thin inductor (internal coil type), the one having the structure shown in FIG. 1 is conventionally known.
FIG. 3A is a plan view of the planar inductor, and FIG. 3B is a sectional view taken along the line AA. Spiral plane coils 2a and 2b are provided on both sides of the insulating substrate 1 and are electrically connected through the through holes 3. An inductor is formed between the terminals 6a and 6b by sandwiching the planar coils 2a and 2b with the magnetic films 5a and 5b via the insulating films 4a and 4b, respectively. Planar coil 2a in plan view
(Solid line) and 2b (broken line) are loci of the center line of the coil cross section.

A resin material such as polyimide is used for the insulating substrate 1, and a ceramic material such as alumina, zirconia, or aluminum nitride can also be applied. Since the thermal conductivity of the ceramic material is 100 to 1000 times higher than that of the resin material, it is easy to dissipate the heat generated by the loss in the plane coil and the magnetic film, and is suitable for preventing the temperature rise. By increasing the heat dissipation, the flat coil 2 can generate a larger current.
It becomes possible to flow to a and 2b, and it is possible to store and convert larger energy. That is, it can be miniaturized (energy is proportional to the square of the current). In addition, the bending strength of ceramic materials is about 10 times greater than that of resin materials,
Since high bending resistance can be obtained with the same thickness, it is suitable for preventing the flat coil or the magnetic film from being damaged or the magnetic film being subjected to bending stress to reduce the inductance due to the inverse magnetostriction effect.

The insulating films 4a and 4b are provided in order to prevent a short circuit because they are electrically connected to the magnetic film when a current is applied to the plane coil, and a polymer film such as polyimide or an inorganic film such as SiO ₂ or glass is applied. ing. As described above, a nonmagnetic material has been conventionally applied to the insulating substrate and the insulating film.

The inductor / transformer is required to have a high inductance in order to store and convert energy (energy is proportional to the inductance). However, when a non-magnetic material is used for the insulating substrate and the insulating film, it is difficult to obtain high inductance. Spiral planar coils 2a, 2 of the thin inductor having the structure shown in FIG.
When a current is passed through b, the magnetic flux mainly crosses the non-magnetic insulating substrate 1 and the insulating films 4a and 4b near the center and the outermost portions of the spiral planar coils 2a and 2b, so that the magnetic resistance increases. It is presumed that the inductance decreases because the magnetic flux density decreases.

As the magnetic films 5a and 5b, films and foils of various soft alloys such as cobalt-based and iron-based amorphous alloys and metal soft magnetic materials such as permalloy have been conventionally used. However, since the soft metal magnetic material has a low electric resistance, when the thin inductor / transformer is operated at a high frequency, there is a problem that the heat generation due to the eddy current loss becomes large and the temperature rises.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide an insulating substrate and / or an insulating film in a thin inductor / transformer comprising a spiral planar coil, an insulating film, and a magnetic film laminated on the insulating substrate. By using a magnetic material with high permeability, high saturation magnetic flux density, low power loss and low residual magnetic flux density, the magnetic resistance near the center and the outermost part of the spiral planar coil can be reduced and the magnetic flux density can be increased. Accordingly, it is intended to provide a thin inductor / transformer having high inductance. Another object of the present invention is to provide a thin inductor / transformer with a small temperature rise by reducing heat generation due to eddy current loss at high frequencies by using a magnetic material having high electric resistance and low power loss for the magnetic film.

[0010]

In order to achieve the above object, in the thin inductor / transformer of the present invention, the magnetic permeability and the saturation magnetic flux density of the insulating substrate and / or the insulating film are large, and the power loss and the residual magnetic flux density are large. A small oxide soft magnetic material (soft ferrite) is applied. As the soft oxide magnetic material, Mn-Zn based, Ni-Zn based, Ni-C
u-based, Ni-Cu-Zn-based spinel ferrites,
Although there are garnet-based ferrites such as Al-substituted garnet and Gd-substituted garnet, Ni-Zn-based and Ni-Cu-Zn-based having higher insulation (higher specific resistance) are preferably used.

Instead of the metal soft magnetic material, an oxide soft magnetic material (soft ferrite) having a large specific resistance is applied to the magnetic film. As the soft oxide magnetic material, there are the above-mentioned ones, and a material having a large magnetic permeability and a saturated magnetic flux density at the operating frequency, and a small power loss and a residual magnetic flux density may be selected. By adopting these, the magnetic resistance in the vicinity of the central portion and the outermost portion of the spiral planar coil is low,
The magnetic flux density can be increased and the heat generation due to the eddy current loss at high frequency can be reduced, and the present invention has been completed.

The basic structure of the thin inductor of the present invention is that shown in FIG. The spiral planar coil can be three-dimensionally arranged electrically in series, vertically and / or horizontally via an insulating film, depending on the inductance, the DC superposition characteristic, the size, and the like. A transformer is obtained by providing a plurality of spiral planar coils in parallel. The planar coils 2a and 2b are processed into various shapes by a method of photo-etching the insulating substrate 1 on which a conductive layer is formed in advance, a method of screen-printing a conductive paste on the insulating substrate 1 into various shapes, and then firing. Can be made with. As the method for forming the conductive layer, a method of pressing the conductive foil by pressing or the like, a method of wet plating by electroplating, electroless plating, etc., hot dipping, metal spraying, vapor plating,
Also, there is a method of dry plating such as vacuum deposition such as vacuum deposition, sputtering, and ion plating. Materials applicable to the planar coils 2a and 2b in the present invention include various metals such as copper, silver, gold, platinum, palladium, aluminum and alloys thereof. Plane coil 2
The shapes of a and 2b can be a spiral shape, a zigzag shape, or a combination thereof. To obtain a high inductance, it is advantageous to use a spiral coil.

The material applicable to the insulating films 4a and 4b in the present invention may be an oxide soft magnetic material, a polymer film such as polyimide, or an inorganic film such as SiO ₂ , glass or hard carbon film. Since the inorganic material has a higher thermal conductivity than the polymer, it is easy to radiate the heat generated by the loss in the plane coil or the magnetic film, and is suitable for preventing the temperature rise. Inorganic film is made into (ferrite) paste, printed and baked, electroplating, wet plating by electroless plating, hot-dip plating, thermal spraying, vapor-phase plating, vacuum deposition method, sputtering method, ion plating The film is formed by a dry plating method such as vacuum plating.

The films and foils (strips, plates) applicable to the magnetic films 5a and 5b in the present invention include oxide soft magnetic materials, various amorphous alloys such as cobalt-based and iron-based materials, and super-crystals obtained by crystallizing amorphous alloys. Examples include soft magnetic materials having a fine structure, silicon steel mainly containing silicon, metal soft magnetic materials such as permalloy, permendur, and sendust. The film is made into a paste (ferrite) and printed, then baked, electroplating, electroless plating, wet plating, hot dipping, thermal spraying, vapor phase plating, vacuum deposition, sputtering, ion plating. A film is formed by a method of dry plating such as vacuum plating. Foil (obi,
The plate) is prepared by a quenching method, a molding method, a rolling method, a green sheet method, or the like, and a firing or annealing method.

[0015]

Example 1 An insulating substrate 1 having a thickness of 100 μm and a composition of Ni
Spiral planar coils 2a and 2b were formed by using a Ni—Zn ferrite plate of _0.30 Zn _0.70 Fe ₂ O ₄ and photo-etching a 10 μm-thick Cu layer previously formed on both surfaces. Number of spirals on each side of insulating substrate of spiral flat coil 38, coil side length 12
mm, coil width, spacing 75 μm, coil thickness 10 μm. As the magnetic films 5a and 5b, three compositions with a thickness of 30 μm, Fe _80.5 Si _6.5 B, were prepared by a single roll quenching method.
₁₂ C ₁ , Fe ₇₈ Si ₁₂ B ₁₀ and Co ₇₀ Fe ₅ Si ₁₅ B ₁₀
(atm%) Amorphous alloy ribbon is cut into 14 mm x 14 mm foil, then annealed to form insulating films 4a and 4b with a thickness of 20μ.
It was laminated on the planar coil 1 through a polyimide film of m.

The obtained inductor has a frequency of 500 kHz,
A sinusoidal alternating current with an amplitude of 1 mA was applied and the inductance was measured. Inductance measurement value: 450 to 500 μH Further, using a constant current power supply, a direct current of 100 mA was superimposed on the sine wave alternating current, and the saturation temperature was measured. Measurement temperature: 70 ℃

[0017]

[Comparative Example 1] A spiral planar coil 2a, 2b was formed by a method of using a polyimide film having a thickness of 100 µm for an insulating substrate 1 and photo-etching a Cu layer having a thickness of 10 µm previously formed on both surfaces. .. Number of spirals on each side of insulating substrate of spiral planar coil, coil side length 12 mm, coil width, spacing 75 μm, coil thickness 1
It is 0 μm. As the magnetic films 5a and 5b, three kinds of compositions Fe _80.5 having a thickness of 30 μm formed by the single roll quenching method were used.
Si _6.5 B ₁₂ C ₁ , Fe ₇₈ Si ₁₂ B ₁₀ and Co ₇₀ Fe ₅
Amorphous alloy ribbon of Si ₁₅ B ₁₀ (atm%) 14mm ×
After being cut into 14 mm foil, it was annealed and laminated on the planar coil 1 as the insulating films 4a and 4b via a polyimide film having a thickness of 20 μm.

The obtained inductor has a frequency of 500 kHz,
A sinusoidal alternating current with an amplitude of 1 mA was applied and the inductance was measured. Inductance measurement value: 300 to 350 μH Further, using a constant current power supply, a direct current of 100 mA was superimposed on the sine wave alternating current, and the saturation temperature was measured. Measurement temperature: 80 ℃

[0019]

Example 2 An insulating substrate 1 having a thickness of 100 μm and a composition of Ni
Spiral planar coils 2a and 2b were formed by using a Ni—Zn ferrite plate of _0.30 Zn _0.70 Fe ₂ O ₄ and photo-etching a 10 μm-thick Cu layer previously formed on both surfaces. Number of spirals on each side of insulating substrate of spiral flat coil 38, coil side length 12
mm, coil width, spacing 75 μm, coil thickness 10 μm. As the magnetic films 5a and 5b, 14 mm × 14 mm and 1
Composition (MnO) ₃₅ (ZnO) molded to a thickness of 00 μm
An Mn—Zn-based ferrite plate of ₁₂ (Fe ₂ O ₃ ) ₅₃ was laminated on the planar coil 1 as the insulating films 4a and 4b via a polyimide film having a thickness of 20 μm.

The obtained inductor has a frequency of 500 kHz,
A sinusoidal alternating current with an amplitude of 1 mA was applied and the inductance was measured. Inductance measurement value: 550 μH Further, using a constant current power supply, a direct current of 100 mA was superimposed on the sine wave alternating current, and the saturation temperature was measured. Measurement temperature: 67 ° C

[0021]

Example 3 An insulating substrate 1 having a thickness of 100 μm and a composition of Ni
Spiral planar coils 2a and 2b were formed by using a Ni—Zn ferrite plate of _0.30 Zn _0.70 Fe ₂ O ₄ and photo-etching a 10 μm-thick Cu layer previously formed on both surfaces. Number of spirals on each side of insulating substrate of spiral flat coil 38, coil side length 12
mm, coil width, spacing 75 μm, coil thickness 10 μm. As the magnetic films 5a and 5b, 14 mm × 14 mm and 1
Ni-Zn system (composition Ni _0.30 Z
n _0.70 Fe ₂ O ₄ ), Ni-Cu-Zn system (composition Ni
A ferrite plate of _0.1 Cu _0.25 Zn _0.65 Fe ₂ O ₄ ) was laminated on the plane coil 1. Ni-Zn system, Ni-Cu-
Since Zn-based ferrite has a specific resistance of about 10 ⁷ Ω · cm, it is not necessary to provide an insulating film. Since the specific resistance of Mn-Zn ferrite is about 10 to 10 ³ Ω · cm, it is necessary to provide an insulating film.

The obtained inductor has a frequency of 500 kHz,
A sinusoidal alternating current with an amplitude of 1 mA was applied and the inductance was measured. Inductance measurement value: 350 to 500 μH Further, using a constant current power supply, a direct current of 100 mA was superimposed on a sine wave alternating current, and a saturation temperature was measured. Measurement temperature: 62 ℃

[0023]

[Embodiment 4] The insulating substrate 1 has a thickness of 100 μm and a composition of Ni.
_{Using a 0.30} Zn _0.70 Fe ₂ O ₄ Ni-Zn ferrite plate, the spiral flat coils 2a and 2b were formed by screen-printing Ag paste and then firing. Number of spirals on each side of insulating substrate of spiral planar coil 38, coil side length 12mm, coil width, spacing 75μ
m, and the coil thickness is 10 μm. As the insulating films 4a and 4b, glass paste was screen-printed on the planar coils 2a and 2b and then baked to be laminated to a thickness of 20 μm. As the magnetic films 5a and 5b, three compositions having a thickness of 30 μm, Fe _80.5 Si, prepared by a single roll quenching method were used.
_6.5 B ₁₂ C ₁ , Fe ₇₈ Si ₁₂ B ₁₀ and Co ₇₀ Fe ₅ Si
₁₅ B ₁₀ (atm%) amorphous alloy ribbon 14 mm x 14
After cutting into a foil of mm, it was annealed and laminated on the insulating film.

The obtained inductor has a frequency of 500 kHz,
A sinusoidal alternating current with an amplitude of 1 mA was applied and the inductance was measured. Inductance measurement value: 450 to 500 μH Further, using a constant current power supply, a direct current of 100 mA was superimposed on the sine wave alternating current, and the saturation temperature was measured. Measurement temperature: 65 ° C

[0025]

COMPARATIVE EXAMPLE 2 A 100 μm thick alumina plate is used as the insulating substrate 1, and the spiral planar coils 2a and 2b are made of Ag.
The paste was screen-printed and then fired to form. Number of spirals on each side of insulating substrate of spiral planar coil, coil side length 12 mm, coil width, interval 75
μm, coil thickness 10 μm. As the insulating films 4a and 4b, glass paste was screen-printed on the planar coils 2a and 2b and then baked to be laminated to a thickness of 20 μm. As the magnetic films 5a and 5b, three compositions having a thickness of 30 μm, Fe _80.5 Si, prepared by a single roll quenching method were used.
_6.5 B ₁₂ C ₁ , Fe ₇₈ Si ₁₂ B ₁₀ and Co ₇₀ Fe ₅ Si
₁₅ B ₁₀ (atm%) amorphous alloy ribbon 14 mm x 14
After cutting into a foil of mm, it was annealed and laminated on the insulating film.

The obtained inductor has a frequency of 500 kHz,
A sinusoidal alternating current with an amplitude of 1 mA was applied and the inductance was measured. Inductance measurement value: 3000 to 350 μH Further, using a constant current power supply, a direct current of 100 mA was superimposed on the sine wave alternating current, and the saturation temperature was measured. Measurement temperature: 65 ° C

[0027]

[Embodiment 5] The insulating substrate 1 has a thickness of 100 μm and a composition of Ni.
_{Using a 0.30} Zn _0.70 Fe ₂ O ₄ Ni-Zn ferrite plate, the spiral flat coils 2a and 2b were formed by screen-printing Ag paste and then firing. Number of spirals on each side of insulating substrate of spiral planar coil 38, coil side length 12mm, coil width, spacing 75μ
m, and the coil thickness is 10 μm. As the insulating films 4a and 4b, Ni-Zn-based (composition N
i _0.30 Zn _0.70 Fe ₂ O ₄ ), Ni-Cu-Zn-based (composition Ni _0.1 Cu _0.25 Zn _0.65 Fe ₂ O ₄ ) ferrite fine particles (particle diameter 0.1 μm) are pasted into a paste, and then baked. By doing so, it was laminated to a thickness of 20 μm. As the magnetic films 5a and 5b, three compositions of Fe _80.5 Si having a thickness of 60 μm prepared by the single roll quenching method were used.
_6.5 B ₁₂ C ₁ , Fe ₇₈ Si ₁₂ B ₁₀ and Co ₇₀ Fe ₅ Si
₁₅ B ₁₀ (atm%) amorphous alloy ribbon 14 mm x 14
After cutting into a foil of mm, it was annealed and laminated on the insulating film.

The obtained inductor has a frequency of 500 kHz,
A sinusoidal alternating current with an amplitude of 1 mA was applied and the inductance was measured. Inductance measurement value: 500 to 550 μH Further, using a constant current power source, a direct current of 100 mA was superimposed on the sine wave alternating current, and the saturation temperature was measured. Measurement temperature: 65 ° C

[0029]

[Embodiment 6] The insulating substrate 1 has a thickness of 100 μm and a composition of Ni.
_{Using a 0.30} Zn _0.70 Fe ₂ O ₄ Ni-Zn ferrite plate, the spiral flat coils 2a and 2b were formed by screen-printing Ag paste and then firing. Number of spirals on each side of insulating substrate of spiral planar coil 38, coil side length 12mm, coil width, spacing 75μ
m, and the coil thickness is 10 μm. As the insulating films 4a and 4b, glass paste was screen-printed on the planar coils 2a and 2b and then baked to be laminated to a thickness of 20 μm. The magnetic films 5a and 5b are preliminarily 14 mm × 14 m
m (MnO) ₃₅ (Z
A Mn—Zn-based ferrite plate of nO) ₁₂ (Fe ₂ O ₃ ) ₅₃ was laminated on the insulating film.

The obtained inductor has a frequency of 500 kHz,
A sinusoidal alternating current with an amplitude of 1 mA was applied and the inductance was measured. Inductance measurement value: 550 μH Further, using a constant current power supply, a direct current of 100 mA was superimposed on the sine wave alternating current, and the saturation temperature was measured.

Measurement temperature: 62 ° C.

[0032]

[Embodiment 7] The insulating substrate 1 has a thickness of 100 μm and a composition of Ni.
_{Using a 0.30} Zn _0.70 Fe ₂ O ₄ Ni-Zn ferrite plate, the spiral flat coils 2a and 2b were formed by screen-printing Ag paste and then firing. Number of spirals on each side of insulating substrate of spiral planar coil 38, coil side length 12mm, coil width, spacing 75μ
m, and the coil thickness is 10 μm. As the insulating films 4a and 4b, glass paste was screen-printed on the planar coils 2a and 2b and then baked to be laminated to a thickness of 20 μm. As the magnetic films 5a and 5b, Mn—Zn based ferrite fine particles (particle size 0.1 μm) having the composition (MnO) ₃₅ (ZnO) ₁₂ (Fe ₂ O ₃ ) ₅₃ are pasted on the insulating films 4a and 4b. Was repeatedly screen-printed and then fired to form a laminate having a thickness of 100 μm.

The obtained inductor has a frequency of 500 kHz,
A sinusoidal alternating current with an amplitude of 1 mA was applied and the inductance was measured. Inductance measurement value: 550 μH Further, using a constant current power supply, a direct current of 100 mA was superimposed on the sine wave alternating current, and the saturation temperature was measured. Measurement temperature: 62 ℃

[0034]

[Embodiment 8] The insulating substrate 1 has a thickness of 100 μm and a composition of Ni.
_{Using a 0.30} Zn _0.70 Fe ₂ O ₄ Ni-Zn ferrite plate, the spiral flat coils 2a and 2b were formed by screen-printing Ag paste and then firing. Number of spirals on each side of insulating substrate of spiral planar coil 38, coil side length 12mm, coil width, spacing 75μ
m, and the coil thickness is 10 μm. As the insulating films 4a and 4b, glass paste was screen-printed on the planar coils 2a and 2b and then baked to be laminated to a thickness of 20 μm. Further, stacking was repeated in the same manner, and three layers each of the flat coil and the insulating film were stacked on both surfaces of the insulating substrate 1.

Insulating films 4a, 4 are used as the magnetic films 5a, 5b.
on b, the composition (MnO) ₃₅ (ZnO) ₁₂ (Fe ₂ O ₃ )
₅₃ Mn-Zn ferrite fine particles (particle size 0.1 μm)
The paste-formed product was screen-printed and then fired repeatedly to form a laminate having a thickness of 200 μm.

The obtained inductor has a frequency of 500 kHz,
A sinusoidal alternating current with an amplitude of 1 mA was applied and the inductance was measured. Inductance measurement value: 1600 μH Further, using a constant current power supply, a direct current of 100 mA was superimposed on a sine wave alternating current, and the saturation temperature was measured. Measurement temperature: 72 ° C

[0037]

[Embodiment 9] An insulating substrate 1 having a thickness of 100 μm and a composition of Ni
_{Using a 0.30} Zn _0.70 Fe ₂ O ₄ Ni-Zn ferrite plate, the spiral flat coils 2a and 2b were formed by screen-printing Ag paste and then firing. Number of spirals on each side of insulating substrate of spiral planar coil 38, coil side length 12mm, coil width, spacing 75μ
m, and the coil thickness is 10 μm. As the insulating films 4a and 4b, Ni-Zn-based (composition N
i _0.30 Zn _0.70 Fe ₂ O ₄ ), Ni-Cu-Zn-based (composition Ni _0.1 Cu _0.25 Zn _0.65 Fe ₂ O ₄ ) ferrite fine particles (particle size 0.1 μm) are pasted and baked after screen printing. By doing so, it was laminated to a thickness of 20 μm. As the magnetic films 5a and 5b, 14 mm × 14 mm,
Composition (MnO) ₃₅ (ZnO) molded to a thickness of 100 μm
_{A 12} (Fe ₂ O ₃ ) ₅₃ Mn—Zn ferrite plate was laminated on the insulating film.

The obtained inductor has a frequency of 500 kHz,
A sinusoidal alternating current with an amplitude of 1 mA was applied and the inductance was measured. Inductance measurement value: 600 μH Further, using a constant current power supply, a direct current of 100 mA was superimposed on the sine wave alternating current, and the saturation temperature was measured.

Measurement temperature: 62 ° C.

[0040]

Example 10 An insulating substrate 1 having a thickness of 100 μm and a composition of Ni
_{Using a 0.30} Zn _0.70 Fe ₂ O ₄ Ni-Zn ferrite plate, the spiral flat coils 2a and 2b were formed by screen-printing Ag paste and then firing. Number of spirals on each side of insulating substrate of spiral planar coil 38, coil side length 12mm, coil width, spacing 75μ
m, and the coil thickness is 10 μm. As the magnetic films 5a and 5b, N formed in advance to a thickness of 14 mm × 14 mm and 100 μm is used.
i-Zn system (composition Ni _0.30 Zn _0.70 Fe ₂ O ₄ ), Ni
-Cu-Zn system (composition Ni _0.1 Cu _0.25 Zn _0.65 Fe ₂
A ferrite plate of O ₄ ) was laminated on the plane coil 1. N
Since the i-Zn-based and Ni-Cu-Zn-based ferrites have a specific resistance of about 10 ⁷ Ω · cm, it is not necessary to provide an insulating film. Mn-Zn ferrite has a specific resistance of 10 to 10 ³ Ω.
・ Since it is about cm, it is necessary to provide an insulating film.

The obtained inductor has a frequency of 500 kHz,
A sinusoidal alternating current with an amplitude of 1 mA was applied and the inductance was measured. Inductance measurement value: 350 to 500 μH Further, using a constant current power supply, a direct current of 100 mA was superimposed on a sine wave alternating current, and a saturation temperature was measured. Measurement temperature: 62 ℃

[0042]

[Embodiment 11] The insulating substrate 1 has a thickness of 100 μm and a composition of Ni.
_{Using a 0.30} Zn _0.70 Fe ₂ O ₄ Ni-Zn ferrite plate, the spiral flat coils 2a and 2b were formed by screen-printing Ag paste and then firing. Number of spirals on each side of insulating substrate of spiral planar coil 38, coil side length 12mm, coil width, spacing 75μ
m, and the coil thickness is 10 μm. As the magnetic films 5a and 5b, Ni-Zn based (composition N
i _0.30 Zn _0.70 Fe ₂ O ₄ ), Ni-Cu-Zn-based (composition Ni _0.1 Cu _0.25 Zn _0.65 Fe ₂ O ₄ ) ferrite fine particles (particle diameter 0.1 μm) are pasted into a paste, and then baked. By repeating
It was laminated to a thickness of 00 μm. Ni-Zn system, Ni-Cu-
Since Zn-based ferrite has a specific resistance of about 10 ⁷ Ω · cm, it is not necessary to provide an insulating film. Since the specific resistance of Mn-Zn ferrite is about 10 to 10 ³ Ω · cm, it is necessary to provide an insulating film.

The obtained inductor has a frequency of 500 kHz,
A sinusoidal alternating current with an amplitude of 1 mA was applied and the inductance was measured. Inductance measurement value: 350 to 500 μH Further, using a constant current power supply, a direct current of 100 mA was superimposed on a sine wave alternating current, and a saturation temperature was measured. Measurement temperature: 62 ℃

[0044]

Twelfth Embodiment A Ni-Zn-based (composition Ni
_0.30 Zn _0.70 Fe ₂ O ₄ ) and Ni—Cu—Zn-based (composition Ni _0.1 Cu _0.25 Zn _0.65 Fe ₂ O ₄ ) ferrite green sheets are used, and spiral planar coils 2a and 2b are Ag paste. Was formed by screen printing.

The planar coil 2 is used as the magnetic films 5a and 5b.
Ni-Zn system (composition Ni _0.30 Zn _0.70 F
e ₂ O ₄ ), Ni-Cu-Zn system (composition Ni _0.1 Cu
Green sheets of ferrite of _0.25 Zn _0.65 Fe ₂ O ₄ ) were laminated. The laminated body was dried, pressure-bonded with a hot press, dried and fired to obtain an inductor. Number of spirals of a pair of spiral planar coils in the inductor 38, coil side length 12 mm, coil width, spacing 75 μm,
The coil thickness is 10 μm. Insulating substrate 1, magnetic film 5a,
The thickness of the ferrite portion corresponding to 5b is also 100 μm. Since the specific resistance of Ni-Zn based and Ni-Cu-Zn based ferrites is about 10 ⁷ Ω · cm, it is not necessary to provide an insulating film.

The obtained inductor has a frequency of 500 kHz,
A sinusoidal alternating current with an amplitude of 1 mA was applied and the inductance was measured. Inductance measurement value: 350 to 500 μH Further, using a constant current power supply, a direct current of 100 mA was superimposed on a sine wave alternating current, and a saturation temperature was measured. Measurement temperature: 62 ℃

[0047]

According to the present invention, in a thin inductor / transformer comprising a spiral planar coil, an insulating film and a magnetic film laminated on an insulating substrate, the insulating substrate and / or the insulating film have a magnetic permeability and a saturation magnetic flux. By using an oxide soft magnetic material (soft ferrite) with high density, low power loss, and low residual magnetic flux density, the magnetic resistance is reduced near the center and the outermost part of the spiral planar coil.
By increasing the magnetic flux density, a thin inductor / transformer with high inductance can be obtained. In addition, by using an oxide soft magnetic material (soft ferrite) with high electrical resistance and low power loss for the magnetic film, heat generation due to eddy current loss at high frequencies is reduced, and a thin inductor / transformer with low temperature rise is provided. can get.

[Brief description of drawings]

FIG. 1 is a structural example of a thin inductor / transformer of the present invention, in which (a) is a plan view and (b) is a sectional view.

[Explanation of symbols]

 1: Insulating substrate 2a, 2b: Spiral planar coil 3: Through hole 4a, 4b: Insulating film 5a, 5b: Magnetic film 6a, 6b: Terminal

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takao Yamada 228 Kayajuku, Nakahara-ku, Kawasaki-shi, Kanagawa Yutaka Electric Manufacturing Co., Ltd.

Claims (4)

[Claims] 1. A thin inductor / transformer comprising a spiral planar coil, an insulating film, and a magnetic film laminated on a substrate of an oxide soft magnetic material (soft ferrite). 2. The thin inductor according to claim 1, wherein the insulating film is an oxide soft magnetic material (soft ferrite).
Trance. 3. The thin inductor according to claim 1, wherein the magnetic film is an oxide soft magnetic material (soft ferrite).
Trance. 4. The thin inductor / transformer according to claim 1, wherein the insulating film and the magnetic film are oxide soft magnetic materials (soft ferrite).