JP7255526B2 - Coil component manufacturing method - Google Patents

Description

The present invention relates to a method of manufacturing a coil component.

Conventionally, there is a coil component described in Japanese Patent Application Laid-Open No. 2017-59749 (Patent Document 1). The coil component includes an element body and a coil provided in the element body, and the coil includes a plurality of laminated coil conductors. A stress relieving space is provided in the element body in contact with the surface of the coil conductor. ZrO ₂ powder is present in the stress relief space.

JP 2017-59749 A

By the way, when trying to actually manufacture the conventional coil component, a paste containing ZrO ₂ powder is applied to the ceramic green sheet by screen printing or the like to form a powder pattern that becomes a stress relaxation space. . Subsequently, a conductive paste is applied to the powder pattern formed on the ceramic green sheet by screen printing or the like, thereby forming a conductor pattern that will become each coil conductor after firing. After that, the stress relaxation space is formed by baking the powder pattern. As described above, it is necessary to print a paste such as ZrO ₂ on the ceramic green sheet, which may complicate the process.

Accordingly, an object of the present disclosure is to provide a method of manufacturing a coil component that can easily form a gap.

In order to solve the problem, a method for manufacturing a coil component, which is one aspect of the present disclosure, includes:
a preparation step of preparing a first unfired magnetic layer containing a magnetic material and a first binder, and a second unfired magnetic layer containing a magnetic material and a second binder different from the first binder;
a stacking step of stacking the unfired coil wiring between the first unfired magnetic layer and the second unfired magnetic layer;
The first unfired magnetic layer, the second unfired magnetic layer, and the unfired coil wiring are fired to form the first magnetic layer after firing the first unfired magnetic layer and the coil wiring after firing the unfired coil wiring. and a firing step of forming a gap between the second magnetic layer after firing of the second unfired magnetic layer and the coil wiring by bringing them into contact with each other.

Here, the unfired magnetic layer is, for example, a magnetic sheet or magnetic paste. The unfired coil wiring is, for example, conductor paste.

According to the aspect, since the first binder of the first unfired magnetic layer and the second binder of the second unfired magnetic layer are different, the binding force between the first unfired magnetic layer and the unfired coil wiring and the second binder are different. 2 different from the bonding force between the green magnetic layer and the green coil wiring. Then, in the firing step, the first magnetic layer having the stronger coupling force is brought into contact with the coil wiring, and a gap is formed between the second magnetic layer having the weaker coupling force and the coil wiring. Therefore, the void can be easily formed.

Preferably, in one embodiment of the coil component manufacturing method, the decomposition temperature of the second binder is lower than the decomposition temperature of the first binder.

Here, the decomposition temperature of the binder is measured using a Tg-MS (Thermogravimetry Mass Spectrometer) under conditions of 3.5% O ₂ concentration and a temperature increase rate of 5 ° C./min. It is the temperature at which the generated gas derived from the binder material disappears.

According to the above embodiment, even if the second binder having a lower decomposition temperature disappears first in the firing process, the first binder having a higher decomposition temperature remains without being decomposed. The coupling force between the coil wires is stronger than the coupling force between the second unfired magnetic layer and the unfired coil wires. As a result, the gap can be easily formed on the side of the second binder that disappears first, that is, between the second magnetic layer and the coil wiring.

Preferably, in one embodiment of the coil component manufacturing method,
The decomposition temperature of the first binder is 400° C. or higher and 420° C. or lower,
The decomposition temperature of the second binder is 300° C. or higher and 350° C. or lower.

According to the above embodiment, even if the second binder completely disappears in the firing process, the first binder can remain without being decomposed.

Preferably, in one embodiment of the coil component manufacturing method,
the first binder is either PVB, PVA, polyvinyl acetate, or polyethylene;
The second binder is either acrylic, polyurethane, polyvinyl chloride, or polystyrene.

Preferably, in one embodiment of the coil component manufacturing method, the shrinkage start temperature of the conductor powder contained in the unsintered coil wiring is 300° C. or higher and 350° C. or lower.

Here, the contraction start temperature of the conductor powder contained in the unfired coil wiring means that the conductor powder contained in the unfired coil wiring starts to shrink when neck growth occurs and the distance between the particles of the conductor powder becomes smaller. means temperature.

According to the above-described embodiment, in the firing process, the second binder disappears and the first binder remains, and the unfired coil wiring can be shrunk. Voids can be easily formed.

Preferably, in one embodiment of the coil component manufacturing method, the conductor powder contained in the green coil wiring contains Ag.

Preferably, in one embodiment of the coil component manufacturing method, the decomposition temperature of the binder contained in the unfired coil wiring is lower than the decomposition temperature of the second binder.

According to the embodiment, in the firing process, before the second binder starts to decompose, the binder contained in the unfired coil wiring disappears, and the conductor powder contained in the unfired coil wiring neck grows and shrinks. can do.

Preferably, in one embodiment of the coil component manufacturing method, the decomposition temperature of the binder contained in the unfired coil wiring is 200° C. or higher and 300° C. or lower.

According to the above embodiment, even if the binder contained in the unfired coil wiring completely disappears in the firing process, the second binder can remain without being decomposed.

Preferably, in one embodiment of the coil component manufacturing method, the binder contained in the green coil wiring is ethyl cellulose.

Preferably, in one embodiment of the method for manufacturing a coil component, in the lamination step, the second unfired magnetic layer, the unfired coil wiring, the first unfired magnetic layer, the unfired coil wiring, and the second unfired magnetic layer are stacked in order.

According to the above embodiment, the number of the first unfired magnetic layers, the second unfired magnetic layers, and the unfired coil wiring can be reduced to reduce the height of the coil component.

Preferably, in one embodiment of the method for manufacturing a coil component, in the lamination step, the first unfired magnetic layer, the unfired coil wiring, the second unfired magnetic layer, the first unfired magnetic layer, the unfired coil wiring, and , the second unfired magnetic layers are laminated in order.

According to the above-described embodiment, the gaps can be unevenly distributed on one side (second magnetic layer side) in the stacking direction with respect to the coil wiring.

Preferably, in one embodiment of the coil component manufacturing method, in the lamination step, the third unfired magnetic layer is formed between the first unfired magnetic layer and the second unfired magnetic layer, in the same layer as the unfired coil wiring, and in the same layer as the unfired coil wiring. are stacked so as to sandwich the

According to the above embodiment, the thickness of the coil wiring can be maintained and the DC resistance value (Rdc) of the coil wiring can be reduced by forming the third unfired magnetic layer in the same layer as the unfired coil wiring.

According to the method for manufacturing a coil component, which is one aspect of the present disclosure, the gap can be easily formed.

1 is a perspective view showing a first embodiment of a coil component; FIG. FIG. 2 is a cross-sectional view of the coil component of FIG. 1 taken along the line XX; 4 is an exploded plan view of the coil component; FIG. It is an expanded sectional view around coil wiring. It is sectional drawing which shows the manufacturing method of coil components. It is sectional drawing which shows the manufacturing method of coil components. It is sectional drawing which shows the manufacturing method of coil components. FIG. 4 is a schematic diagram of decomposition timing of the first magnetic sheet, the second magnetic sheet, and the coil conductor paste during firing. FIG. 3 is a schematic diagram based on an image showing the state of the first magnetic layer, the second magnetic layer, and the coil wiring after firing. FIG. 8 is an exploded plan view showing a second embodiment of the coil component; FIG. 5 is an enlarged cross-sectional view showing a second embodiment of the coil component; FIG. 11 is an enlarged cross-sectional view showing a third embodiment of the coil component;

Hereinafter, a method for manufacturing a coil component, which is one aspect of the present disclosure, will be described in detail with reference to the illustrated embodiments. Note that the drawings are partially schematic and may not reflect actual dimensions or proportions.

(First embodiment)
FIG. 1 is a perspective view showing a first embodiment of a coil component. FIG. 2 is a cross-sectional view taken along line XX of FIG. 1, and a cross-sectional view taken along line LT passing through the center in the W direction. FIG. 3 is an exploded plan view of the coil component, showing views along the T direction from the bottom to the top. The L direction is the length direction of the coil component 1 , the W direction is the width direction of the coil component 1 , and the T direction is the height direction of the coil component 1 . Hereinafter, the forward direction of the T direction is also referred to as the upper side, and the reverse direction of the T direction is also referred to as the lower side.

As shown in FIGS. 1, 2, and 3, the coil component 1 includes a base body 10, a coil 20 provided inside the base body 10, and a coil 20 provided on the surface of the base body 10. It has a first external electrode 31 and a second external electrode 32 which are connected.

The coil component 1 is electrically connected to wiring of a circuit board (not shown) via first and second external electrodes 31 and 32 . The coil component 1 is used, for example, as a noise removal filter, and is used in electronic equipment such as personal computers, DVD players, digital cameras, TVs, mobile phones, and car electronics.

The element body 10 is formed in a substantially rectangular parallelepiped shape. The surface of the base body 10 has a first end face 15, a second end face 16 positioned opposite the first end face 15, and four side faces 17 positioned between the first end face 15 and the second end face 16. . The first end surface 15 and the second end surface 16 face each other in the L direction.

The element body 10 includes a plurality of first magnetic layers 11 and second magnetic layers 12 . The first magnetic layers 11 and the second magnetic layers 12 are alternately laminated in the T direction. The first magnetic layer 11 and the second magnetic layer 12 are made of, for example, a magnetic material such as a Ni--Cu--Zn based ferrite material. Each thickness of the first magnetic layer 11 and the second magnetic layer 12 is, for example, 5 μm or more and 30 μm or less. Note that the element body 10 may partially include a non-magnetic layer.

The first external electrode 31 covers the entire surface of the first end surface 15 of the element body 10 and the end portion of the side surface 17 of the element body 10 on the first end surface 15 side. The second external electrode 32 covers the entire surface of the second end surface 16 of the element body 10 and the end portion of the side surface 17 of the element body 10 on the second end surface 16 side. The first external electrode 31 is electrically connected to the first end of the coil 20 and the second external electrode 32 is electrically connected to the second end of the coil 20 . The first external electrode 31 may be L-shaped so as to extend over the first end surface 15 and one side surface 17 , and the second external electrode 32 may be formed over the second end surface 16 and one side surface 17 . It may be an L-shape formed across.

The coil 20 is spirally wound along the T direction. Coil 20 is made of a conductive material such as Ag or Cu, for example. The coil 20 has a plurality of coil wirings 21 and a plurality of lead conductor layers 61 and 62 .

The two-layered first lead conductor layers 61, the plurality of coil wirings 21, and the two-layered second lead conductor layers 62 are arranged in order in the T direction and electrically connected in order through via conductors. A plurality of coil wires 21 are connected in order in the T direction to form a spiral along the T direction. The first lead conductor layer 61 is exposed from the first end surface 15 of the element body 10 and is connected to the first external electrode 31, and the second lead conductor layer 62 is exposed from the second end surface 16 of the element body 10 and is connected to the first external electrode 31. 2 is connected to the external electrode 32 . The number of layers of the first and second lead conductor layers 61 and 62 is not particularly limited, and for example, each may be one layer.

The coil wiring 21 is formed in a shape wound in less than one turn on a plane. The lead conductor layers 61 and 62 are formed in a linear shape. The thickness of the coil wiring 21 is, for example, 10 μm or more and 40 μm or less. The thickness of the first and second lead conductor layers 61 and 62 is, for example, 30 μm, but may be thinner than the thickness of the coil wiring 21 .

The coil wiring 21 is sandwiched between the first magnetic layer 11 and the second magnetic layer 12 . In FIG. 3, the second magnetic layer 12 is hatched for clarity. Since the coil wire 21 is sandwiched between the first and second magnetic layers 11 and 12, the shape of the coil wire 21 is elliptical in a cross section perpendicular to the extending direction (winding direction) of the coil wire 21. It has a shape.

Specifically, along the T direction, there are two layers of the first magnetic layers 11, nine layers of the second magnetic layers 12, and four layers of the coil wiring 21. FIG. Hereinafter, each of the first magnetic layer 11, the second magnetic layer 12, and the coil wire 21 is referred to as "numbered" counting from the bottom. Then, in order along the T direction, the fourth second magnetic layer 12, the first first magnetic layer 11, the fifth second magnetic layer 12, the second first magnetic layer 11, and the sixth A second magnetic layer 12 is disposed. A first coil wire 21, a second coil wire 21, a third coil wire 21, and a fourth coil wire 21 are arranged in order along the T direction.

The first coil wiring 21 is arranged between the fourth second magnetic layer 12 and the first first magnetic layer 11, and the first coil wiring 21 is arranged between the first magnetic layer 11 and the fifth second magnetic layer 12. A second coil wire 21 is arranged between them, a third coil wire 21 is arranged between the fifth second magnetic layer 12 and the second first magnetic layer 11, and a second coil wire 21 is arranged between the second magnetic layer 11 and the second magnetic layer 11. and the sixth second magnetic layer 12, the fourth coil wire 21 is arranged.

The first and second lead conductor layers 61 and 62 are provided in layers different from the coil wiring 21, respectively. The first and second lead conductor layers 61 and 62 are sandwiched between the two second magnetic layers 12, respectively.

FIG. 4 is an enlarged sectional view around the coil wiring 21 of FIG. As shown in FIGS. 2 and 4, a void portion 51 exists within the element body 10 . The air gap 51 is located between the second magnetic layer 12 and the coil wiring 21 .

Specifically, a gap portion 51 is provided between the fourth second magnetic layer 12 and the first coil wire 21, and a gap portion 51 is provided between the fifth second magnetic layer 12 and the second coil wire 21. A gap portion 51 is provided between the fifth second magnetic layer 12 and the third coil wiring 21 , and a gap portion 51 is provided between the sixth second magnetic layer 12 and the fourth coil wiring 21 . A portion 51 is provided. Thus, the gaps 51 are provided alternately vertically along the T direction.

The air gap 51 is provided along the entire interface between the coil wire 21 and the second magnetic layer 12, but may be provided partially along a part of the interface. The thickness of the void 51 may be constant or may vary. The maximum thickness of the void 51 is, for example, 0.5 μm or more and 8 μm or less.

By providing the air gap 51, the stress on the magnetic layers 11 and 12 caused by the temperature change of the coil wiring 21 caused by the difference in thermal expansion coefficient between the coil wiring 21 and the magnetic layers 11 and 12 can be suppressed. As a result, deterioration of inductance and impedance characteristics due to internal stress can be eliminated.

Next, a method for manufacturing the coil component 1 will be described with reference to FIGS. 5A to 5C.

First, a first green magnetic layer 111 containing a magnetic material and a first binder, and a second green magnetic layer 112 containing a magnetic material and a second binder different from the first binder are prepared. This is called a preparation process. The first unfired magnetic layer 111 is in a state before the first magnetic layer 11 is fired. The second unfired magnetic layer 112 is in a state before the second magnetic layer 12 is fired.

After that, the unfired coil wiring 121 is laminated between the first unfired magnetic layer 111 and the second unfired magnetic layer 112 . This is called a lamination process. That is, as shown in FIG. 5A, the first unfired coil wiring 121 is stacked on the fourth (see FIG. 3) second unfired magnetic layer 112 . The unfired coil wiring 121 is in a state before firing of the coil wiring 21 . As shown in FIG. 5B, the first first unfired magnetic layer 111 is stacked on the fourth second unfired magnetic layer 112 and the first unfired coil wiring 121 . As shown in FIG. 5C, the second unfired coil wiring 121 is laminated on the first first unfired magnetic layer 111, and the first unfired magnetic layer 111 and the second unfired coil wiring are stacked. A fifth second unfired magnetic layer 112 is laminated on 121 . Furthermore, this is repeated several times to form a laminated block body. After that, the laminated block body is separated into individual pieces.

After that, the first unfired magnetic layer 111, the second unfired magnetic layer 112, and the unfired coil wiring 121 are fired, and as shown in FIG. 11 and the coil wiring 21 after firing of the unfired coil wiring 121 are brought into contact with each other, and a gap 51 is formed between the second magnetic layer 12 after firing of the second unfired magnetic layer 112 and the coil wiring 21 . This is called a firing process. After that, as shown in FIG. 1, external electrodes 31 and 32 are provided on the element body 10, and the coil component 1 is manufactured.

According to the method of manufacturing the coil component 1, the first binder for the first unfired magnetic layer 111 and the second binder for the second unfired magnetic layer 112 are different, so the first unfired magnetic layer 111 and the unfired coil wiring are different. The coupling force between 121 and the coupling force between the second unfired magnetic layer 112 and the unfired coil wire 121 are different. Then, in the firing process, the first magnetic layer 11 having the stronger coupling force and the coil wiring 21 are brought into contact with each other, and the gap 51 is formed between the second magnetic layer 12 having the weaker coupling force and the coil wiring 21 . to form Therefore, the void 51 can be easily formed.

In the stacking step, the second unfired magnetic layer 112, the unfired coil wiring 121, the first unfired magnetic layer 111, the unfired coil wiring 121, and the second unfired magnetic layer 112 are sequentially stacked. By reducing the numbers of the first unfired magnetic layer 111, the second unfired magnetic layer 112, and the unfired coil wiring 121, the height of the coil component 1 can be reduced.

Preferably, the decomposition temperature of the second binder is lower than the decomposition temperature of the first binder. Here, the decomposition temperature of the binder is measured using a Tg-MS (Thermogravimetry Mass Spectrometer) under conditions of 3.5% O ₂ concentration and a temperature increase rate of 5 ° C./min. It is the temperature at which the generated gas derived from the binder material disappears.

According to this, even if the second binder having a lower decomposition temperature disappears first in the firing process, the first binder having a higher decomposition temperature remains without being decomposed. The coupling force between the wires 121 is stronger than the coupling force between the second green magnetic layer 112 and the green coil wire 121 . Thereby, the gap 51 can be easily formed on the side of the second binder that disappears first, that is, between the second magnetic layer 12 and the coil wiring 21 .

Preferably, the decomposition temperature of the first binder is 400° C. or higher and 420° C. or lower, and the decomposition temperature of the second binder is 300° C. or higher and 350° C. or lower. According to this, even if the second binder completely disappears in the firing process, the first binder can remain without being decomposed.

Preferably, the first binder is either PVB (polyvinyl butyral), PVA (polyvinyl alcohol), polyvinyl acetate or polyethylene. The second binder is either acrylic, polyurethane, polyvinyl chloride, or polystyrene. Regarding the decomposition temperature, PVB is 420°C, PVA is 420°C, polyvinyl acetate is 420°C, polyethylene is 400°C, acrylic is 330°C, and polyurethane is 325°C. °C, polyvinyl chloride is 300 °C and polystyrene is 350 °C.

The composition of the magnetic material is not particularly limited, but ferrite materials containing Fe ₂ O ₃ , ZnO, CuO and NiO, for example, can be used. When the magnetic material contains Fe ₂ O ₃ , ZnO, CuO and NiO, the contents of these are, for example, Fe ₂ O ₃ is 40.0 mol % or more and 49.5 mol % or less, ZnO is 5 mol % or more and 35 mol % or less, CuO is 8 mol % or more and 12 mol % or less, and NiO is 8 mol % or more and 40 mol % or less. The magnetic material may further contain additives. Examples of additives include Mn ₃ O ₄ , Co ₃ O ₄ , SnO ₂ , Bi ₂ O ₃ and SiO ₂ .

Preferably, the shrinkage start temperature of the conductor powder contained in the green coil wiring 121 is 300° C. or more and 350° C. or less. Here, the contraction start temperature of the conductor powder contained in the unsintered coil wiring 121 means that the conductor powder contained in the unsintered coil wiring 121 undergoes neck growth and the distance between the particles of the conductor powder becomes smaller, causing shrinkage. refers to the starting temperature.

According to this, in the firing process, the unfired coil wiring 121 can be shrunk in a state where the second binder disappears and the first binder remains. The gap 51 can be easily formed by .

Preferably, the conductor powder contained in the green coil wiring 121 contains Ag. Preferably, the decomposition temperature of the binder contained in the green coil wiring 121 is lower than the decomposition temperature of the second binder. According to this, in the firing process, before the decomposition of the second binder starts, the binder contained in the unfired coil wiring 121 disappears, and the conductor powder contained in the unfired coil wiring 121 neck grows and shrinks. can do.

Preferably, the decomposition temperature of the binder contained in the green coil wiring 121 is 200° C. or higher and 300° C. or lower. According to this, even if the binder contained in the unfired coil wiring 121 completely disappears in the firing process, the second binder can remain without being decomposed.

Preferably, the binder contained in the green coil wiring 121 is ethyl cellulose. The decomposition temperature of ethyl cellulose is 280°C.

Next, an example of a method for manufacturing the coil component 1 will be described.

A first magnetic sheet is used as the first unsintered magnetic layer. The thickness of the first magnetic sheet is 35 μm. The magnetic material of the first magnetic sheet is a Ni--Cu--Zn based ferrite material. The first binder of the first magnetic sheet is PVB (polyvinyl butyral), the decomposition temperature of the first binder is 420° C., and the ratio of the first binder is 12 wt %. Note that the ratio of the first binder may be about 8% or more and 14% or less.

A second magnetic sheet is used as the second unsintered magnetic layer. The thickness of the second magnetic sheet is 35 μm. The magnetic material of the second magnetic sheet is a Ni--Cu--Zn based ferrite material. The second binder of the second magnetic sheet is an acrylic resin, the decomposition temperature of the second binder is 330° C., and the ratio of the second binder is 12 wt %. Note that the ratio of the second binder may be about 8% or more and 14% or less.

A coil conductor paste is used as the unfired coil wiring. The conductor powder of the coil conductor paste is Ag, and the average particle size D50 is 1.0 μm. The binder of the coil conductor paste is ethyl cellulose, the decomposition temperature of the binder is 280° C., and the proportion of the binder is 1.5 wt %. In addition, the ratio of the binder may be about 1.0% or more and 2.0% or less.

Then, the first magnetic sheet, the second magnetic sheet, and the coil conductor paste are used to form a laminated block body, which is singulated and then fired.

FIG. 6 is a schematic diagram of decomposition timing of the first magnetic sheet, the second magnetic sheet, and the coil conductor paste during firing. As shown in FIG. 6, the degreasing zone Z12 of the second magnetic sheet has a temperature of about 200° C. or higher and about 330° C. or lower, and the degreasing zone Z11 of the first magnetic sheet has a temperature of about 200° C. or higher and about 420° C. or lower. The “degreasing region” refers to a region from the temperature at which the binder begins to decompose to the temperature at which the decomposition is completed (completely disappears).

The temperature of the degreased region Z21a of the coil conductor paste is approximately 200° C. or higher and approximately 280° C. or lower. The surface diffusion region Z21b of the coil conductor paste has a temperature of approximately 200° C. or more and approximately 320° C. or less. "Surface diffusion region" refers to a region where the conductor powder (Ag) begins to stick to each other when decomposition (degreasing) of the binder starts. A contraction region Z21c of the coil conductor paste is at a temperature of about 320° C. or more and about 700° C. or less. The term “shrinkage region” refers to a region where the conductor portion shrinks due to the neck growth of the conductor powder (Ag) and the reduction in the distance between the particles of the conductor powder.

As shown in FIG. 6, after the degreasing zone Z12 of the second magnetic sheet ends and before the degreasing zone Z11 of the first magnetic sheet ends, the contraction zone Z21c of the coil conductor paste starts. As described above, the second binder of the second magnetic sheet decomposes and disappears at the timing of contraction of the conductor portion of the coil conductor paste during firing, and the first binder of the first magnetic sheet remains without being decomposed. , the coupling force between the conductor portion and the second magnetic sheet becomes weaker than the coupling force between the conductor portion and the first magnetic sheet, and a gap is formed on the side of the second magnetic sheet where the binder has disappeared.

Furthermore, shrinkage of the first magnetic sheet, the second magnetic sheet and the coil conductor paste during firing will be described. That is, the shrinkage of the sheet laminate (state before firing of the element body) formed by laminating the first magnetic sheet and the second magnetic sheet and the shrinkage of the conductor portion (Ag) of the coil conductor paste will be described. This shrinkage is measured, for example, by Thermomechanical Analysis.

Contraction of the conductor portion of the coil conductor paste begins at about 324°C. Shrinkage of the sheet laminate begins at about 800°C. Firing ends at about 900°C. That is, in the first region (approximately 324° C. to approximately 800° C.), the conductor portion of the coil conductor paste shrinks and the sheet laminate does not shrink, so voids are formed. In the second region (approximately 800° C. to approximately 900° C.), the sheet laminate shrinks and the conductor portion of the coil conductor paste does not shrink, so the gap narrows. The shrinkage of the sheet laminate is completed at about 900° C., and the gap formed at this time becomes the gap of the coil component.

FIG. 7 is a schematic diagram based on an image showing the state of the first magnetic layer 11, the second magnetic layer 12, and the coil wiring 21 after firing. In FIG. 7, the cross section of the coil wiring 21 is polished until the cross section can be confirmed, and the image is observed with FE-SEM: JSM-7900F (JEOL Ltd.), low vacuum mode: 20 Pa, WD = 10 mm, detector: LVBEDC and LVSED. to draw the outline of this image. As shown in FIG. 7, a gap 51 is provided between the second magnetic layer 12 and the coil wiring 21, and the first magnetic layer 11 and the coil wiring 21 are in contact with each other.

(Second embodiment)
FIG. 8 is an exploded plan view showing a second embodiment of the coil component, and FIG. 9 is an enlarged sectional view showing the second embodiment of the coil component. The second embodiment differs from the first embodiment (FIGS. 3 and 4) in the position of the coil wiring in the base body. This different configuration is described below. The rest of the configuration is the same as that of the first embodiment, and the same reference numerals as those of the first embodiment are given, and the description thereof is omitted.

As shown in FIGS. 8 and 9, in the coil component 1A of the second embodiment, the element body 10A alternately includes the second magnetic layers 12 and the first magnetic layers 11 along the T direction. Specifically, in order along the T direction, the first magnetic layer 11, the first coil wiring 21, the fourth second magnetic layer 12, the second first magnetic layer 11, the second A coil wiring 21 and a fifth second magnetic layer 12 are laminated. The same applies to the third and fourth coil wirings 21 . A gap 51 is provided between the second magnetic layer 12 and the coil wiring 21 . In this manner, the second magnetic layer 12 is provided on the upper surface of the coil wiring 21 and the air gap portion 51 is provided on the upper surface of the coil wiring 21 .

Explaining the method of manufacturing the coil component 1A of the second embodiment, the lamination process is different from that of the first embodiment. To explain these different stacking processes, the first unfired magnetic layer 111, the first unfired coil wiring 121, the fourth second unfired magnetic layer 112, and the second first unfired magnetic layer 111. , the second unfired coil wiring 121, and the fifth second unfired magnetic layer 112 are laminated in this order. Furthermore, this is repeated several times to form a laminated block body. Since the steps other than the lamination step are the same as those of the first embodiment, the description thereof is omitted.

According to this, the gap portion 51 can be unevenly distributed on one side (the second magnetic layer 12 side) of the stacking direction with respect to the coil wiring 21 .

(Third embodiment)
FIG. 10 is an enlarged cross-sectional view showing a third embodiment of the coil component. The third embodiment differs from the second embodiment (FIG. 9) in the configuration of the element body. This different configuration is described below. Other configurations are the same as those of the first and second embodiments, and the same reference numerals as those of the first and second embodiments are given, and descriptions thereof are omitted.

As shown in FIG. 10 , in the coil component 1B of the third embodiment, the base body 10B includes the third magnetic layer 13 in addition to the first magnetic layer 11 and the second magnetic layer 12 . The third magnetic layer 13 is provided on the same layer as the coil wiring 21 on the first magnetic layer 11 . That is, the third magnetic layer 13 is formed on the first magnetic layer 11 in a region where the coil wiring 21 is not formed. The material of the third magnetic layer 13 may be the same material as the material of the first magnetic layer 11 or the second magnetic layer 12, or may be different. In FIG. 10 , since the material of the third magnetic layer 13 is the same as the material of the second magnetic layer 12 , a gap 51 is provided between the coil wire 21 and the third magnetic layer 13 .

Explaining the method of manufacturing the coil component 1B of the third embodiment, the lamination process is different from that of the second embodiment. To explain this different lamination process, the third unfired magnetic layer is laminated in the same layer as the unfired coil wiring 121 between the first unfired magnetic layer 111 and the second unfired magnetic layer 112 so as to sandwich the third unfired magnetic layer. . The third unfired magnetic layer is in a state before the third magnetic layer 13 is fired. In this case, magnetic paste, for example, is used for the first unfired magnetic layer 111, the second unfired magnetic layer 112, and the third unfired magnetic layer.

According to this, by making the third green magnetic layer the same layer as the green coil wiring 121, the thickness of the coil wiring 21 can be maintained and the DC resistance value (Rdc) of the coil wiring 21 can be reduced.

Note that the present disclosure is not limited to the above-described embodiments, and design changes are possible without departing from the gist of the present disclosure. For example, each characteristic point of the first to third embodiments may be combined in various ways.

In the second and third embodiments, the first magnetic layer 11 is arranged below the coil wire 21 and the second magnetic layer 12 is arranged above the coil wire 21. Two magnetic layers 12 may be arranged and the first magnetic layer 11 may be arranged above the coil wiring 21 . At this time, the gap 51 is formed between the lower surface of the coil wire 21 and the second magnetic layer 12 .

Although the lead conductor layers 61 and 62 are sandwiched between the second magnetic layers 12 in the first to third embodiments, they may be sandwiched between the first magnetic layers 11, whereby the lead conductor layers 61 and 62 Since there is no difference in the bonding force between the two surfaces of the lead conductor layers 61 and 62, the gap 51 is less likely to occur on both surfaces.

In the first to third embodiments, the air gap 51 is formed between the coil wire 21 and the second magnetic layer 12, but is also partially formed between the coil wire 21 and the first magnetic layer 11. may be formed. Also, the coil wiring 21 is composed of a single conductor layer, but may be composed of a plurality of conductor layers that are in surface contact with each other.

Reference Signs List 1, 1A, 1B coil component 10, 10A, 10B base body 11 first magnetic layer 111 first unfired magnetic layer 12 second magnetic layer 112 second unfired magnetic layer 13 third magnetic layer 15 first end surface 16 second second End surface 17 Side surface 20 Coil 21 Coil wiring 121 Unfired coil wiring 31 First external electrode 32 Second external electrode 51 Gap 61 First lead conductor layer 62 Second lead conductor layer

Claims (12)

An unfired coil wiring containing conductor powder; a first unfired magnetic layer containing a magnetic material and a first binder having a decomposition temperature higher than a shrinkage start temperature of the conductor powder; a preparation step of preparing a second unfired magnetic layer containing a second binder having a decomposition temperature lower than the shrinkage start temperature of the conductor powder ;
a stacking step of stacking the unfired coil wiring between the first unfired magnetic layer and the second unfired magnetic layer;
firing the first unfired magnetic layer, the second unfired magnetic layer and the unfired coil wiring, and after firing the first magnetic layer after firing the first unfired magnetic layer and the unfired coil wiring and a firing step of forming a gap between the second magnetic layer after firing of the second unfired magnetic layer and the coil wiring. 2. The method of manufacturing a coil component according to claim 1, wherein the decomposition temperature of said second binder is lower than the decomposition temperature of said first binder. The decomposition temperature of the first binder is 400° C. or higher and 420° C. or lower,
3. The method of manufacturing a coil component according to claim 2, wherein the second binder has a decomposition temperature of 300[deg.] C. or more and 350[deg.] C. or less. The first binder is PVB, PVA, polyvinyl acetate, or polyethylene,
4. The method of manufacturing a coil component according to claim 3, wherein said second binder is acrylic, polyurethane, polyvinyl chloride, or polystyrene. 5. The method of manufacturing a coil component according to claim 3, wherein the conductor powder has a shrinkage start temperature of 300[deg.] C. or more and 350[deg.] C. or less. 6. The method of manufacturing a coil component according to claim 1, wherein said conductor powder contains Ag. 7. The method of manufacturing a coil component according to claim 1, wherein the decomposition temperature of the binder contained in the unfired coil wiring is lower than the decomposition temperature of the second binder. 8. The method for manufacturing a coil component according to claim 7, wherein the decomposition temperature of the binder contained in said unfired coil wiring is 200[deg.] C. or more and 300[deg.] C. or less. 9. The method of manufacturing a coil component according to claim 8, wherein the binder contained in said unsintered coil wiring is ethyl cellulose. 2. The stacking step comprises sequentially stacking the second unfired magnetic layer, the unfired coil wiring, the first unfired magnetic layer, the unfired coil wiring, and the second unfired magnetic layer. 10. A method of manufacturing a coil component according to any one of 9. In the stacking step, the first green magnetic layer, the green coil wiring, the second green magnetic layer, the first green magnetic layer, the green coil wiring, and the second green magnetic layer 10. The method for manufacturing a coil component according to any one of claims 1 to 9, wherein the layers are laminated in order. 2. The laminating step comprises laminating a third unfired magnetic layer in the same layer as the unfired coil wiring between the first unfired magnetic layer and the second unfired magnetic layer so as to sandwich the third unfired magnetic layer. 10. A method of manufacturing a coil component according to any one of 9.

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