JP2021150487A - Manufacturing method of coil component - Google Patents

Abstract

To provide a manufacturing method of a coil component which can easily form a gap.SOLUTION: A manufacturing method of a coil component 1 includes a preparatory step of preparing a first unfired magnetic layer and a second unfired magnetic layer, a laminating step of laminating and sandwiching unfired coil wiring between the first unfired magnetic layer and the second unfired layer, and a firing step of firing the first unfired magnetic layer, the second unfired magnetic layer, and the unfired coil wiring, bringing a first magnetic layer 11 after firing the first unfired magnetic layer into contact with coil wiring 21 after firing the unfired coil wiring, and forming a gap between the second magnetic layer 12 after firing of the second unfired magnetic layer and the coil wiring 21.SELECTED DRAWING: Figure 3

Description

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

Conventionally, as a coil component, there is one described in Japanese Patent Application Laid-Open No. 2017-57949 (Patent Document 1). The coil component includes a body and a coil provided in the body, and the coil includes a plurality of laminated coil conductors. A stress relaxation space in contact with the surface of the coil conductor is provided in the body. _{ZrO 2} powder is present in the stress relaxation space.

Japanese Unexamined Patent Publication No. 2017-57949

By the way, when actually manufacturing a coil component as described above, _{a paste containing ZrO 2} powder is applied onto a ceramic green sheet by screen printing or the like to form a powder pattern serving as a stress relaxation space. .. Subsequently, by applying a conductive paste on the powder pattern formed on the ceramic green sheet by screen printing or the like, a conductor pattern to be each coil conductor is formed after firing. Then, the powder pattern is fired to form a stress relaxation space. As described above, it is necessary to print the paste such as _{ZrO 2} on the ceramic green sheet, which may complicate the process.

Therefore, the present disclosure is to provide a method for manufacturing a coil component capable of easily forming a gap portion.

In order to solve the problem, the method for manufacturing a coil component, which is one aspect of the present disclosure, is
A preparatory step for preparing a first unfired magnetic layer containing a magnetic material and a first binder, and a second unfired magnetic layer containing a second binder different from the magnetic material and the first binder.
A laminating step of laminating the unfired coil wiring between the first unfired magnetic layer and the second unfired magnetic layer so as to sandwich the unfired coil wiring.
The first unfired magnetic layer, the second unfired magnetic layer, and the unfired coil wiring are fired, and the first magnetic layer after firing of the first unfired magnetic layer and the coil wiring after firing of the unfired coil wiring are formed. It is provided with a firing step of contacting the second unfired magnetic layer to form a gap between the second magnetic layer after firing and the coil wiring.

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

According to the above aspect, since the first binder of the first unfired magnetic layer and the second binder of the second unfired magnetic layer are different, the coupling force between the first unfired magnetic layer and the unfired coil wiring and the first. 2 The coupling force between the unfired magnetic layer and the unfired coil wiring is different. Then, in the firing step, the first magnetic layer having a stronger coupling force and the coil wiring are brought into contact with each other, and a gap portion is formed between the second magnetic layer having a weaker coupling force and the coil wiring. Therefore, the void portion 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 by Tg-MS (Thermogravimetry Mass Spectrometer) under the conditions of _{3.5% O 2 concentration and a heating rate of 5 ° C./min.} The temperature at which the generated gas derived from the binder substance disappears.

According to the above embodiment, even if the second binder having a low decomposition temperature disappears first in the firing step, the first binder having a high decomposition temperature remains without being decomposed, so that the first unfired magnetic layer and the unfired are not fired. The coupling force between the coil wirings is stronger than the coupling force between the second unfired magnetic layer and the unfired coil wirings. As a result, a gap portion can be easily formed on the second binder side that disappears first, that is, between the second magnetic layer and the coil wiring.

Preferably, in one embodiment of the method of manufacturing a coil component,
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 disappears completely in the firing step, the first binder can be left without being decomposed.

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

Here, the shrinkage start temperature of the conductor powder contained in the unfired coil wiring is the shrinkage start when the conductor powder contained in the unfired coil wiring grows as a neck and the distance between the particles of the conductor powder becomes smaller. Refers to temperature.

According to the above embodiment, in the firing step, the unfired coil wiring can be contracted with the second binder disappearing and the first binder remaining, and between the second magnetic layer and the coil wiring. The void portion can be easily formed.

Preferably, in one embodiment of the coil component manufacturing method, the conductor powder contained in the unfired 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 above embodiment, in the firing step, before the decomposition of the second binder is started, the binder contained in the unfired coil wiring disappears, and the conductor powder contained in the unfired coil wiring grows as a neck and shrinks. can do.

Preferably, in one embodiment of the method for manufacturing a coil component, 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 step, the second binder can be left without being decomposed.

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

Preferably, in one embodiment of the method for manufacturing a coil component, in the laminating 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 layer, the second unfired magnetic layer, and the unfired coil wiring can be reduced to reduce the height of the coil parts.

Preferably, in one embodiment of the method for manufacturing coil components, in the laminating 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 layer is laminated in order.

According to the above 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 method for manufacturing a coil component, in the laminating step, a 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. Laminate so as to sandwich.

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

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

It is a perspective view which shows the 1st Embodiment of a coil component. FIG. 5 is a cross-sectional view taken along the line XX of the coil component of FIG. It is an exploded plan view of a coil component. It is an enlarged cross-sectional view around the coil wiring. It is sectional drawing which shows the manufacturing method of a coil part. It is sectional drawing which shows the manufacturing method of a coil part. It is sectional drawing which shows the manufacturing method of a coil part. It is a schematic diagram of the decomposition timing of the 1st magnetic sheet, the 2nd magnetic sheet and the coil conductor paste at the time of firing. It is a schematic diagram based on the image which shows the state of the 1st magnetic layer, the 2nd magnetic layer and the coil wiring after firing. It is an exploded plan view which shows the 2nd Embodiment of a coil component. It is an enlarged cross-sectional view which shows the 2nd Embodiment of a coil component. It is an enlarged cross-sectional view which shows the 3rd Embodiment of a 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 embodiment. It should be noted that the drawings include some schematic ones and may not reflect the actual dimensions and ratios.

(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 the line XX of FIG. 1 and is an LT cross-sectional view passing through the center in the W direction. FIG. 3 is an exploded plan view of the coil component, and represents a view along the T direction from the lower view to the upper view. 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 in the T direction is referred to as an upper side, and the reverse direction in the T direction is also referred to as a lower side.

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

The coil component 1 is electrically connected to the wiring of a circuit board (not shown) via the 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 devices 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 body 10 has a first end surface 15, a second end surface 16 located on the opposite side of the first end surface 15, and four side surfaces 17 located between the first end surface 15 and the second end surface 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 a second magnetic layer 12. The first magnetic layer 11 and the second magnetic layer 12 are alternately laminated in the T direction. The first magnetic layer 11 and the second magnetic layer 12 are made of a magnetic material such as a Ni—Cu—Zn-based ferrite material, for example. The thickness of each of the first magnetic layer 11 and the second magnetic layer 12 is, for example, 5 μm or more and 30 μm or less. 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 have an L-shape formed over the first end surface 15 and one side surface 17, and the second external electrode 32 may be formed on the second end surface 16 and one side surface 17. It may be an L-shape formed over.

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

The two layers of the first lead conductor layer 61, the plurality of coil wirings 21, and the two layers of the second lead conductor layer 62 are arranged in order in the T direction and are electrically connected in order via the via conductor. The plurality of coil wirings 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 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 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 may be, for example, one layer each.

The coil wiring 21 is formed in a shape wound on a flat surface in less than one turn. 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 shown by hatching for the sake of clarity. Since the coil wiring 21 is sandwiched between the first and second magnetic layers 11 and 12, the shape of the coil wiring 21 is elliptical in the cross section orthogonal to the extending direction (winding direction) of the coil wiring 21. It is in shape.

Specifically, along the T direction, the first magnetic layer 11 has two layers, the second magnetic layer 12 has nine layers, and the coil wiring 21 has four layers. Hereinafter, each of the first magnetic layer 11, the second magnetic layer 12, and the coil wiring 21 will be referred to as a “number” 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 The second magnetic layer 12 is arranged. Further, the first coil wiring 21, the second coil wiring 21, the third coil wiring 21, and the fourth coil wiring 21 are arranged in order along the T direction.

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

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 cross-sectional view of the periphery of the coil wiring 21 of FIG. As shown in FIGS. 2 and 4, there is a gap 51 in the element body 10. The gap 51 is located between the second magnetic layer 12 and the coil wiring 21.

Specifically, a gap 51 is provided between the fourth second magnetic layer 12 and the first coil wiring 21, and a gap 51 is provided between the fifth second magnetic layer 12 and the second coil wiring 21. A gap 51 is provided, a gap 51 is provided between the fifth second magnetic layer 12 and the third coil wiring 21, and a gap 51 is provided between the sixth second magnetic layer 12 and the fourth coil wiring 21. A section 51 is provided. In this way, the gaps 51 are provided alternately up and down along the T direction.

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

By providing the gap 51, the stress on the magnetic layers 11 and 12 due to the temperature change of the coil wiring 21 caused by the difference in the coefficient of thermal expansion 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 of manufacturing the coil component 1 will be described with reference to FIGS. 5A to 5C.

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

After that, the unfired coil wiring 121 is laminated so as to sandwich the unfired coil wiring 121 between the first unfired magnetic layer 111 and the second unfired magnetic layer 112. This is called a laminating process. That is, as shown in FIG. 5A, the first unfired coil wiring 121 is laminated on the fourth (see FIG. 3) second unfired magnetic layer 112. The unfired coil wiring 121 is a state before firing of the coil wiring 21. As shown in FIG. 5B, the first unfired magnetic layer 111 is laminated on the fourth 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 The fifth second unfired magnetic layer 112 is laminated on the 121. Further, this is repeated a plurality of times to form a laminated block body. Then, this laminated block body is made 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. 4, the first unfired magnetic layer 111 after firing is the first magnetic layer. 11 is brought into contact with the fired coil wiring 21 of the unfired coil wiring 121 to form a gap 51 between the fired second magnetic layer 12 of the second unburned 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 to manufacture the coil component 1.

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

Further, in the laminating 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 laminated in this order. 1 The number of the unfired magnetic layer 111, the second unfired magnetic layer 112, and the unfired coil wiring 121 can be reduced to reduce the height of the coil component 1.

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 by Tg-MS (Thermogravimetry Mass Spectrometer) under the conditions of _{3.5% O 2 concentration and a heating rate of 5 ° C./min.} The temperature at which the generated gas derived from the binder substance disappears.

According to this, even if the second binder having a low decomposition temperature disappears first in the firing step, the first binder having a high decomposition temperature remains without being decomposed. Therefore, the first unfired magnetic layer 111 and the unfired coil The coupling force between the wires 121 is stronger than the coupling force between the second unfired magnetic layer 112 and the unfired coil wiring 121. As a result, the gap 51 can be easily formed on the second binder side 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 disappears completely in the firing step, the first binder can be left 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, and for example, _{a ferrite material containing Fe 2} O ₃ , ZnO, CuO, and NiO can be used. When the magnetic material _{contains Fe 2} O ₃ , ZnO, CuO and NiO, the contents thereof are, for example, 40.0 mol% or more and 49.5 mol% or less _{for Fe 2} O _{3 and 5 mol% or more for ZnO.} It is in the range of 35 mol% or less, CuO of 8 mol% or more and 12 mol% or less, and NiO of 8 mol% or more and 40 mol% or less. The magnetic material may further contain additives. Examples of the additive 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 unfired coil wiring 121 is 300 ° C. or higher and 350 ° C. or lower. Here, the shrinkage start temperature of the conductor powder contained in the unfired coil wiring 121 means that the conductor powder contained in the unfired coil wiring 121 grows as a neck and shrinks when the distance between the particles of the conductor powder becomes smaller. The starting temperature.

According to this, in the firing step, the unfired coil wiring 121 can be contracted with the second binder disappearing and the first binder remaining, and between the second magnetic layer 12 and the coil wiring 21. The gap 51 can be easily formed.

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

Preferably, the decomposition temperature of the binder contained in the unfired 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 step, the second binder can be left without being disassembled.

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

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

A first magnetic sheet is used as the first unfired 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%. 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 unfired 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%. The ratio of the second binder may be about 8% or more and 14% or less.

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 ratio of the binder is 1.5 wt%. The binder ratio may be about 1.0% or more and 2.0% or less.

Then, a laminated block body is formed by using the first magnetic sheet, the second magnetic sheet, and the coil conductor paste, and after individualizing, firing is performed.

FIG. 6 is a schematic diagram of the 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 region Z12 of the second magnetic sheet is about 200 ° C. or higher and about 330 ° C. or lower, and the degreasing region Z11 of the first magnetic sheet is about 200 ° C. or higher and about 420 ° C. or lower. The "solvent degreasing region" refers to the region from the temperature at which the binder begins to decompose to the temperature at which the decomposition is completed (completely disappears).

The degreasing region Z21a of the coil conductor paste is about 200 ° C. or higher and about 280 ° C. or lower. The surface diffusion region Z21b of the coil conductor paste is about 200 ° C. or higher and about 320 ° C. or lower. The “surface diffusion region” refers to a region where the conductor powders (Ag) begin to stick to each other at the start of decomposition (degreasing) of the binder. The shrinkage region Z21c of the coil conductor paste is about 320 ° C. or higher and about 700 ° C. or lower. The “shrinkage region” refers to a region in which the conductor powder (Ag) grows as a neck and the conductor portion shrinks as the distance between the particles of the conductor powder becomes smaller.

As shown in FIG. 6, after the end of the degreasing region Z12 of the second magnetic sheet and before the end of the degreasing region Z11 of the first magnetic sheet, the shrinkage region Z21c of the coil conductor paste is started. In this way, at the time of shrinkage of the conductor portion of the coil conductor paste during firing, the second binder of the second magnetic sheet is decomposed and disappears, and the first binder of the first magnetic sheet remains without being decomposed. The bonding force between the conductor portion and the second magnetic sheet is weaker than the bonding force between the conductor portion and the first magnetic sheet, and a gap portion is formed on the second magnetic sheet side where the binder has disappeared.

Further, the 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.

Shrinkage of the conductor portion of the coil conductor paste begins at about 324 ° C. Shrinkage of the sheet laminate begins at about 800 ° C. The firing is completed at about 900 ° C. That is, in the first region (about 324 ° C. to about 800 ° C.), the conductor portion of the coil conductor paste shrinks and the sheet laminate does not shrink, so that a gap portion is formed. In the second region (about 800 ° C. to about 900 ° C.), the sheet laminate shrinks and the conductor portion of the coil conductor paste does not shrink, so that the gap portion becomes narrower. 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 view based on an image showing the states of the first magnetic layer 11, the second magnetic layer 12, and the coil wiring 21 after firing. In FIG. 7, 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.) in low vacuum mode: 20 Pa, WD = 10 mm, and detectors: LVBEDC and LVSED. And drew 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 cross-sectional view showing the second embodiment of the coil component. The second embodiment is different from the first embodiment (FIGS. 3 and 4) in the position of the coil wiring in the element body. This different configuration will be described below. Other configurations are the same as those of the first embodiment, and the same reference numerals as those of the first embodiment are assigned and the description thereof will be 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 layer 12 and the first magnetic layer 11 along the T direction. Specifically, the first magnetic layer 11, the first coil wiring 21, the fourth second magnetic layer 12, the second first magnetic layer 11, and the second in order along the T direction. The coil wiring 21 and the 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. As described above, the second magnetic layer 12 is provided on the upper surface of the coil wiring 21, and the gap 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 laminating process is different from that of the first embodiment. Explaining this different laminating process, the first unfired magnetic layer 111, the first unfired coil wiring 121, the fourth unfired magnetic layer 112, and the second first unfired magnetic layer 111. The second unfired coil wiring 121 and the fifth unfired magnetic layer 112 are laminated in this order. Further, this is repeated a plurality of times to form a laminated block body. Since it is the same as the first embodiment except for the laminating step, the description thereof will be omitted.

According to this, the gap 51 can be unevenly distributed on one side (second magnetic layer 12 side) in 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 is different from the second embodiment (FIG. 9) in the configuration of the element body. This different configuration will be 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 the description thereof will be omitted.

As shown in FIG. 10, in the coil component 1B of the third embodiment, the element body 10B includes a 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 first magnetic layer 11 in the same layer as the coil wiring 21. 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 wiring 21 and the third magnetic layer 13.

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

The present disclosure is not limited to the above-described embodiment, and the design can be changed without departing from the gist of the present disclosure. For example, the feature points 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 wiring 21, and the second magnetic layer 12 is arranged above the coil wiring 21, but the second magnetic layer 12 is arranged below the coil wiring 21. The 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 portion 51 is formed between the lower surface of the coil wiring 21 and the second magnetic layer 12.

In the first to third embodiments, the lead conductor layers 61 and 62 are sandwiched between the second magnetic layers 12, but may be sandwiched between the first magnetic layers 11 and thereby the lead conductor layers 61 and 62. Since there is no difference in the bonding force on both sides of the lead conductor layers 61 and 62, the gaps 51 are less likely to occur on both sides of the lead conductor layers 61 and 62.

In the first to third embodiments, the gap 51 is formed between the coil wiring 21 and the second magnetic layer 12, but is also partially formed between the coil wiring 21 and the first magnetic layer 11. It may be formed. Further, although the coil wiring 21 is composed of one conductor layer, a plurality of conductor layers may be formed in surface contact with each other.

1,1A, 1B Coil parts 10,10A, 10B Element body 11 1st magnetic layer 111 1st unfired magnetic layer 12 2nd magnetic layer 112 2nd unfired magnetic layer 13 3rd magnetic layer 15 1st end face 16 2nd End face 17 Side surface 20 Coil 21 Coil wiring 121 Unfired coil wiring 31 1st external electrode 32 2nd external electrode 51 Air gap 61 1st lead conductor layer 62 2nd lead conductor layer

Claims (12)

A preparatory step for 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 laminating step of laminating the unfired coil wiring between the first unfired magnetic layer and the second unfired magnetic layer so as to sandwich the unfired coil wiring.
After firing the first unfired magnetic layer, the second unfired magnetic layer, and the unfired coil wiring, and firing the first magnetic layer after firing the first unfired magnetic layer and the unfired coil wiring. A method for manufacturing a coil component, comprising a firing step of contacting the coil wiring of the above and forming a gap between the second magnetic layer after firing of the second unfired magnetic layer and the coil wiring. The method for manufacturing a coil component according to claim 1, wherein the decomposition temperature of the second binder is lower than the decomposition temperature of the first binder. The decomposition temperature of the first binder is 400 ° C. or higher and 420 ° C. or lower.
The method for manufacturing a coil component according to claim 2, wherein the decomposition temperature of the second binder is 300 ° C. or higher and 350 ° C. or lower. The first binder is either PVB, PVA, polyvinyl acetate, or polyethylene.
The method for manufacturing a coil component according to claim 3, wherein the second binder is any one of acrylic, polyurethane, polyvinyl chloride, and polystyrene. The method for manufacturing a coil component according to claim 3 or 4, wherein the shrinkage start temperature of the conductor powder contained in the unfired coil wiring is 300 ° C. or higher and 350 ° C. or lower. The method for manufacturing a coil component according to any one of claims 1 to 5, wherein the conductor powder contained in the unfired coil wiring contains Ag. The method for manufacturing a coil component according to any one of claims 1 to 6, wherein the decomposition temperature of the binder contained in the unfired coil wiring is lower than the decomposition temperature of the second binder. The method for manufacturing a coil component according to claim 7, wherein the decomposition temperature of the binder contained in the unfired coil wiring is 200 ° C. or higher and 300 ° C. or lower. The method for manufacturing a coil component according to claim 8, wherein the binder contained in the unfired coil wiring is ethyl cellulose. In the laminating 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 laminated in this order, claim 1. The method for manufacturing a coil component according to any one of 1 to 9. In the laminating 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 layer. The method for manufacturing a coil component according to any one of claims 1 to 9, wherein the coils are laminated in order. In the laminating step, the first unfired magnetic layer and the second unfired magnetic layer are laminated on the same layer as the unfired coil wiring so as to sandwich the third unfired magnetic layer. The method for manufacturing a coil component according to any one of 1 to 9.

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