JP2002110423A - Common mode choke coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a common mode choke coil which can be increased in magnetic coupling, can be reduced in height, and has a high breakdown voltage. SOLUTION: This common mode choke coil is formed on a support substrate 1, and the main body 3 of the coil is held between magnetic layers 2. The main body 3 is provided with a first conductor line 6 which is formed in spiral shape, a second conductor line 7 which is also formed in spiral shape at a prescribed interval from the first line 6, and an insulator 8 covering the first and second lines 6 and 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a common mode choke coil used as an electric circuit element, and more particularly to a common mode choke coil provided on a mother board such as a printed wiring board and a ceramic board.

[0002]

2. Description of the Related Art Conventionally, a winding type and a laminated type are known as common mode choke coils. The wire-wound common mode choke coil is formed by winding two insulated conductors around a magnetic core such as ferrite and fixing it with resin or molding the whole.

As a laminated common mode choke coil, a powder is pasted, a first conductor line and a second conductor line are provided in a magnetic material by a printing lamination method or a sheet lamination method.
They are fired simultaneously.

Further, a common mode choke coil as disclosed in Japanese Patent Application Laid-Open No. 2000-49013 is known.

As shown in FIG. 6, the common mode choke coil disclosed in this publication includes an insulating substrate 51, a plurality of insulating resin layers 53 formed on the insulating substrate 51, and one counting from the insulating substrate 51. A first conductor line 55 formed in a spiral between the second and third insulating resin layers 53 and a second conductor line formed in a spiral between the second and third insulating resin layers 53 57.

In such a common mode choke coil, when an in-phase current flows through two conductors, the magnetic flux is added and the impedance increases. Conversely, when opposite-phase currents flow in the two conductors, the magnetic flux is canceled out and almost no impedance is generated. As described above, the common mode choke coil is an electronic component having a filter function that a common-mode current is unlikely to flow and a reverse-phase current is likely to flow, and is used for noise suppression components.

[0007]

In the field of information and communication equipment in which such a common mode choke coil is used, there is a demand for smaller and lighter parts. This is not suitable for miniaturization.

[0008] The multilayer common mode choke coil is suitable for miniaturization, but has a drawback that characteristic values, particularly inductance, are largely varied due to misalignment of the multilayer. As described above, when the inductance difference between the two conductor lines (coils) increases, the normal mode impedance increases, causing a problem that not only the common mode current but also the normal mode current to be passed is attenuated.

Furthermore, the common mode choke coil disclosed in Japanese Patent Application Laid-Open No. 2000-49013 is more suitable for miniaturization than a wound type. When focusing on one conductor line, it is manufactured by one patterning. Although there is a characteristic that the variation in inductance is small,
Since the insulating resin layer between the two conductor lines is insulated, the thickness of the insulating resin layer must be increased,
When the thickness is increased, the magnetic coupling between the two conductor lines is reduced, causing a problem that the common mode impedance is reduced. Conversely, if the insulating resin layer between the two conductor lines is made thinner in order to increase the magnetic coupling between the conductor lines, there is a problem that the insulation resistance is reduced.

SUMMARY OF THE INVENTION An object of the present invention is to provide a common mode choke coil having a high withstand voltage capable of increasing the magnetic coupling and reducing the height.

[0011]

A common mode choke coil according to the present invention is a common mode choke coil formed on a support substrate and having a coil body sandwiched between magnetic layers, wherein the coil body has a spiral shape. A first conductor line formed in a shape, a second conductor line formed in a spiral shape so as to extend along the first conductor line at a predetermined interval, and covering the first conductor line and the second conductor line And an insulator.

According to such a common mode choke coil, for example, when a conductor line is formed by a sputtering method, the first conductor line is formed on the same plane using a mask for previously forming two conductor lines. Since the second conductor line and the second conductor line are formed at the same time, the insulation can be obtained without forming an insulator for insulation between the two conductor lines. Even if it is, an excellent withstand voltage can be maintained.

In addition, because of the excellent withstand voltage as described above, two conductor lines, that is, a first conductor line and a second conductor line, can be provided adjacent to each other. Although the magnetic fields cancel each other out, the magnetic fields other than between the lines strengthen each other, so that the magnetic coupling can be increased.

Furthermore, since the coil body is sandwiched between the magnetic layers, the magnetic coupling between the two conductor lines is further enhanced,
The size of the common mode choke coil can be reduced. Furthermore, since the two conductor lines are formed on the same plane, the height can be reduced.

In the common mode choke coil according to the present invention, the first conductor line has an inverted trapezoidal cross section, and the second conductor line has a rectangular or trapezoidal cross section.
The thickness of the conductor line is smaller than that of the first conductor line.

According to this structure, the second conductor line having a rectangular or trapezoidal cross section and a small thickness is disposed between the first conductor lines having an inverted trapezoidal cross section.
By narrowing the distance between the conductor lines, the first conductor line and the second conductor line can be formed close to each other. For example, the distance between the first conductor line and the second conductor line can be increased from above the support substrate without impairing the insulation. 1 μm or less, and the magnetic coupling can be further increased and the size can be further reduced.

Further, in the present invention, it is preferable that the diameter of the conductive particles forming the first conductive line gradually decreases from the surface of the first conductive line toward the support substrate.
This makes it possible to produce conductor lines having an interval of 1 μm or less without impairing the insulation.

[0018]

FIG. 1 is a sectional view of a common mode choke coil according to the present invention. This common mode choke coil is formed on a support substrate 1 and has a magnetic layer 2 formed thereon.
And is configured to sandwich the coil body 3.

As shown in FIGS. 1 to 3, the coil main body 3 has a first conductor line 6 formed in a spiral shape, and a spiral shape formed along the first conductor line 6 at a predetermined interval. The second conductor line 7 and the first conductor line 6
And an insulator 8 covering each of the second conductor lines 7.

That is, the first conductor line 6 and the second conductor line 7
Are formed in a spiral shape while being formed in parallel. Note that the first conductor line 6 is shown by diagonal lines.

FIG. 2 schematically shows a common mode choke coil according to the present invention. In the figure, a thick solid line indicates the first conductor line 6, and a thick chain line indicates the second conductor line 7. A thin solid line is a lead line of the first conductor line 6, and a thin chain line is a lead line of the second conductor line 7. Although not shown in the drawing, the lead lines cross via the via-hole conductors formed in the support substrate 1 without being in electrical contact with the first and second conductor lines 6 and 7.

As the supporting substrate 1, any material having an insulating property may be used, but Al ₂ O ₃ is particularly preferable, and ferrite, glass, silicon or the like exhibiting soft magnetism can also be applied.

The first conductor line 6 is formed by a photolithography technique, a film forming technique such as sputtering. As a film formation method, a vacuum evaporation and plating method can be applied other than the sputtering.

The conductor material of the first conductor line 6 and the second conductor line 7 is preferably Au or Cu,
Ag or the like can also be applied. From the viewpoint that the first conductor line 6 has an inverted trapezoidal shape, it is desirable to form Au by the sputtering method.

The maximum width of the first conductor line 6 is 5 to 50 μm,
The thickness t ₁ is preferably 2 to 20 μm because the inverted trapezoidal shape is formed after etching, and because the size and the Q value are large, the maximum width of the second conductor line 7 is 5 to 70 μm.
m and a thickness t ₂ of 1 to 15 μm are desirable because electrical contact with the first conductor line 6 is avoided.

As shown in FIG. 3, the cross section of the first conductor line 6 has a rectangular shape (an inverted trapezoidal shape) in which the length of the side on the support substrate 1 side is shorter than the length of the side of the surface. The second conductor line 7 has a rectangular cross section, and the second conductor line 7 having a rectangular cross section is disposed between the first conductor lines 6 having an inverted trapezoidal cross section. That is, the second conductor line 7 is housed in a trapezoidal space having a cross section formed between the first conductor lines 6. The line is designed so that the self-inductance of the first conductor line 6 and the self-inductance of the second conductor line 7 are equal.

In such a common mode choke coil, the two lines 6 and 7 are on the same plane and have a structure sandwiched between each other, so that the magnetic field between the two conductor lines 6 and 7 is canceled each other. However, since the magnetic fields other than between the lines 6 and 7 reinforce each other, the magnetic coupling can be increased.
In addition, since the structure can be insulated without the insulator 8, excellent withstand voltage can be maintained even if a part of the insulator 8 has a defect.

The magnetic layer 2 is manufactured by a photolithography technique or a film forming technique such as sputtering. As a film formation method, a vacuum evaporation and plating method can be applied other than the sputtering. When the magnetic layer 2 is formed in this way, the common mode impedance can be increased because the magnetic coupling is further strengthened.

The thickness of the magnetic layer 2 is 1 to 10 μm, and is made of a material such as FeNi, FeSiAl, Co-based amorphous, and soft magnetic ferrite.

The taper angle θ of the first conductor line 6 is set to 60 to prevent electrical contact between the first conductor line 6 and the second conductor line 7 and to keep the shape of the first conductor line 6 stable. Preferably, it is 80 °.

The thickness t ₂ of the second conductor line 7 is smaller than the thickness t ₁ of the first conductor line 6.
In particular, it is desirable that the thickness t ₂ of the second conductor line 7 is 70% or less of the thickness t ₁ of the first conductor line 6. By setting the thickness t ₂ of the second conductor line 7 to 70% or less of the thickness t ₁ , conduction between the first conductor line 6 and the second conductor line 7 can be reliably prevented, and the first conductor line 6 The insulator 8 can be reliably filled between the second conductor line 7 and the second conductor line 7. The insulator 8
Is made of SiO ₂ , Si ₃ N ₄ , Al ₂ O ₃ , polyimide, and benzocyclolobutene (BCB) material.

Further, in the present invention, the distance L between the first conductor line 6 and the second conductor line 7 is 1 when viewed from above the support substrate 1.
μm or less, particularly 0.5 μm. This is because by reducing the distance between the first conductor line 6 and the second conductor line 7, the size can be reduced, and at the same time, the Q factor can be increased.

In the present invention, as shown in FIG. 3C, the diameter of the conductive particles 9 forming the first conductive line 6 is larger than that of the support particles 1 on the surface of the support particles 1. Is gradually reduced from the surface of the first conductor line 6 toward the support substrate 1. Thus, the diameter of the conductive particles 9 is
By gradually reducing the size toward the support substrate 1, the first conductor line 6 formed by the sputtering method can be easily formed into an inverted trapezoidal cross section by etching.
Although the first conductive line 6 in FIG. 3C has a blank on the support substrate 1 side, the description is omitted because it is difficult to describe because it is fine.

It should be noted that, as shown in FIG.
May have a trapezoidal cross section. In this case, the first
Since the distance between the conductor line 6 and the second conductor line 17 can be reduced almost uniformly in the film thickness direction and a wider cross-sectional area of the second conductor line 17 can be obtained, the Q value of the inductor can be increased. Such a trapezoidal line can be manufactured by a film formation method having a flying component other than the straightness, for example, by sputtering film formation.

In a common mode choke coil as shown in FIG. 4, the distance between the first conductor line 6 and the second conductor line 17 can be reduced almost uniformly in the film thickness direction. Can be increased and the size can be reduced.

Further, a soft magnetic substrate may be used instead of the magnetic layer. Further, the first conductor line and the second conductor line can be simultaneously formed using a plating method. In this case, the process can be simplified and the product can be manufactured with high productivity.

A method for manufacturing the common mode choke coil of the present invention will be described. First, the magnetic layer 2 is formed on the support substrate 1 by a photolithography technique or a film forming technique such as sputtering.
To form Similarly, an insulator 8 is formed on the magnetic material layer 2 by a photolithography technique or a film forming technique such as sputtering. As shown in FIG.
As shown in FIG.
An Au film 14 having a thickness of 0 μm is formed, and a Ti film 15 is formed on the Au film 14 in a thickness of 0.02 to 0.1 μm.

Next, as shown in FIG. 5B, a positive photoresist 16 is formed on the Ti film 15 to form a pattern.

Next, as shown in FIG.
A part of the i film 15 is HF based aqueous solution, and a part of the Au film 14 is K
The first conductor line 6 having an inverted trapezoidal shape (an inverted tapered shape) is formed by wet etching using a CN aqueous solution until the insulator 8 is exposed.

The condition for the first conductor line 6 to have a reverse taper after etching is that the crystal grains become smaller in the direction in which the Au film 14 is deposited, that is, the crystal grains from the surface of the Au film 14 to the support substrate 1. Needs to be small.

In this embodiment, the diameter of the crystal grains immediately after the deposition of the Au film 14 (substrate surface) is about 0.01 to 0.1 μm, and the diameter of the crystal grains on the film surface is about 0.5 to 2.0 μm. It is desirable that As described above, as the film forming conditions for changing the diameter of the crystal grains of the Au film 14 in the film thickness direction, the substrate temperature during film formation is 100 to 300 ° C., and the film forming rate by sputtering is 0.2 to 0.6 μm / m is desirable. Note that the taper angle θ can be changed depending on the size of the crystal grains.

Next, as shown in FIG. 5D, the positive photoresist 16 is removed. Next, after a resist is applied to the entire surface, the resist is patterned so as to expose the first conductor line 6. Thereafter, as shown in FIG. 5E, Au is formed to a thickness of 1.0 to 3.5 μm by a vapor deposition method, and Au is formed on the upper surface of the first conductor line 6 and on the magnetic layer 2 between the first conductor lines 6. A film 19 is formed. A formed on the magnetic layer 2
The u film 19 has a rectangular cross section and serves as the second conductor line 7.

The second conductor line 7 is manufactured by a sputtering or vapor deposition method. Second conductor line 7 by sputtering
When manufactured, a line having a trapezoidal cross section can be formed, and when manufactured by vapor deposition, a line having a rectangular cross section can be manufactured. Since the first conductor line 6 has an inverse taper, the first conductor line 6
The distance between the conductor line 6 and the second conductor line 7 is short.

Thereafter, the Ti film 15 is etched with an HF aqueous solution. When the etching of the Ti film 15 is completed, the Au deposited on the Ti film 15 is lifted off, and the conductor lines 6 and 7 are formed as shown in FIG. Since the Ti film 15 is intended for lift-off as described above, it is not limited to the Ti film. For example, the present invention can be implemented with SiO ₂ which is a dielectric.

Thereafter, an insulator 8 is formed between the conductor lines 6 and 7 and on the conductor lines 6 and 7 by sputtering or vapor deposition, and the magnetic layer 2 is formed on the insulator 8 in the same manner as described above. To obtain the common mode choke coil of the present invention.

In the common mode choke coil configured as described above, the two conductor lines 6 and 7 are simultaneously formed on the same plane so as not to conduct, so that they are insulated between the two conductor lines 6 and 7. Even if a part of the insulator 8 has a defect, an excellent withstand voltage can be maintained even if a part of the insulator 8 is defective. The two conductor lines 6, 7 of the conductor line 6 and the second conductor line 7 can be provided adjacent to each other, and the fields of the two conductor lines 6, 7 cancel each other.
Magnetic fields can be strengthened, so that the magnetic coupling can be increased.

Further, since the coil body 3 is sandwiched between the magnetic layers 2, the magnetic coupling between the two conductor lines 6 and 7 can be further increased, and the size of the common mode choke coil can be reduced. Since the two conductor lines 6 and 7 are formed on the same plane, the height can be reduced.

[0048]

According to the common mode choke coil of the present invention, since the first conductor line and the second conductor line are formed simultaneously on the same plane so as not to conduct, an insulator for insulating between the two conductor lines is provided. Even without forming, because of the structure that can be insulated, excellent withstand voltage can be maintained even if there is a defect in part of the insulator. The two conductor lines, the first conductor line and the second conductor line, can be provided adjacent to each other, and the magnetic fields between the two conductor lines cancel each other out. In addition, since the coil body is sandwiched between the magnetic layers, the magnetic coupling between the two conductor lines can be increased and the size can be reduced.
Furthermore, since the two conductor lines are formed on the same plane, the height can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a common mode choke coil of the present invention.

FIG. 2 is a schematic diagram illustrating a first conductor line and a second conductor line.

3A and 3B show a common mode choke coil according to the present invention, wherein FIG. 3A is a transverse sectional view, FIG. 3B is a longitudinal sectional view of FIG.
(C) is an enlarged cross-sectional view showing a cross section of the first conductor line.

FIG. 4 is a cross-sectional view showing an example in which a second conductor line having a trapezoidal cross section is formed between the first conductor lines.

FIG. 5 is a process chart showing a method for manufacturing a common mode choke coil according to the present invention.

FIG. 6 is a sectional view showing a conventional common mode choke coil.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Support substrate 2 ... Magnetic layer 3 ... Coil body 6 ... 1st conductor line 7, 17 ... 2nd conductor line 8 ... Insulator 9 ... Conductor particle

Claims (3)

[Claims] 1. A common mode choke coil formed on a supporting substrate and having a coil body sandwiched between magnetic layers, wherein the coil body is formed in a first spiral shape.
A conductor line, a second conductor line spirally formed along the first conductor line at a predetermined interval, and an insulator covering the first conductor line and the second conductor line. A common mode choke coil characterized by: 2. A cross section of the first conductor line having an inverted trapezoidal shape.
2. The common mode choke coil according to claim 1, wherein the cross section of the conductor line is rectangular or trapezoidal, and the thickness of the second conductor line is smaller than that of the first conductor line. 3. The common mode choke coil according to claim 1, wherein the diameter of the conductive particles forming the first conductive line gradually decreases from the surface of the first conductive line toward the support substrate. .