Laminated coil components

Abstract

To provide a multilayer coil component capable of improving bonding strength of outer electrodes.SOLUTION: A multilayer coil component 1 includes: a multilayer body 10 that includes a plurality of insulating layers 31 laminated and that is provided with a coil 30 inside the multilayer body; and an outer electrode that is provided at a surface of the multilayer body and connected to the coil. The multilayer body has a first end surface 11 and a second end surface 12 facing each other in a length direction, a first main surface 13 and a second main surface 14 facing each other in a height direction perpendicular to the length direction, and a first side surface and a second side surface facing each other in a width direction perpendicular to the length and height directions. The outer electrode includes a first outer electrode 21 extending from at least a portion of the first end surface to a portion of the first main surface, and a second outer electrode 22 extending from at least a portion of the second end surface to a portion of the first main surface. Each outer electrode includes a base electrode containing at least Ag and glass. A diffusion length of the glass from an interface between the outer electrode and the multilayer body toward the multilayer body is 2.44 μm or more and 6.90 μm or less.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a multilayer coil component.

Background Art

[0002] Patent Document 1 discloses a multilayer electronic component manufactured by processing a concave groove in a green sheet, printing a plurality of conductive pastes in the concave groove in the vertical and horizontal directions, laminating a plurality of green sheets to form a plurality of coils inside, cutting, firing, and providing terminal electrodes at both ends. The coil conductor composed of the conductive paste has a part of the coil conductor overlapping on both sides of the concave groove in the cross-sectional shape after firing, and the aspect ratio t / w of the thickness t and width w of the cross-section of the coil conductor is 0.7 or more.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the multilayer coil component described in Patent Document 1, the bonding strength of the terminal electrode corresponding to the external electrode may be insufficient.

[0005] The present invention has been made to solve the above problems, and an object thereof is to provide a multilayer coil component capable of increasing the bonding strength of an external electrode.

Means for Solving the Problems

[0006] The laminated coil component of the present invention comprises a laminate formed by laminating a plurality of insulating layers in the lamination direction and having a coil provided inside, and an external electrode provided on the surface of the laminate and electrically connected to the coil, wherein the laminate has a first end face and a second end face opposite each other in the longitudinal direction, a first main surface and a second main surface opposite each other in the height direction perpendicular to the longitudinal direction, and a first side surface and a second side surface opposite each other in the width direction perpendicular to the longitudinal direction and the height direction, wherein the external electrode has a first external electrode extending from at least a part of the first end face of the laminate to a part of the first main surface, and a second external electrode extending from at least a part of the second end face of the laminate to a part of the first main surface, wherein the external electrode has a base electrode containing at least Ag and glass, and the distance over which the glass has diffused from the interface between the external electrode and the laminate to the laminate is 2.44 μm or more and 6.90 μm or less. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a laminated coil component that can increase the bonding strength of the external electrodes. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic perspective view showing an example of a laminated coil component of the present invention. [Figure 2] Figure 2 is a schematic cross-sectional view showing an example of a laminated coil component of the present invention. [Figure 3] Figure 3 is a schematic exploded perspective view showing the insulating layers that make up the laminated coil component shown in Figure 2. [Figure 4] Figure 4 is a schematic exploded plan view illustrating the insulating layers that make up the laminated coil component shown in Figure 2. [Figure 5] Figure 5 is a schematic diagram illustrating the method for measuring the diffusion distance of glass (Bi). [Figure 6] Figure 6 is a scatter plot of the diffusion distance of glass (Bi) and the adhesion force at which the fracture probability is 1% for the laminated coil components of Examples 1-6 and Comparative Examples 1-3. [Modes for carrying out the invention]

[0009] The laminated coil component of the present invention will be described below. However, the present invention is not limited to the following configurations and embodiments, and can be modified and applied as appropriate without altering the essence of the invention. Furthermore, combinations of two or more of the individual preferred configurations and embodiments of the present invention described below also constitute the present invention.

[0010] Figure 1 is a schematic perspective view showing an example of a laminated coil component of the present invention. The laminated coil component 1 shown in Figure 1 comprises a laminate (base body) 10, a first external electrode 21, and a second external electrode 22. The laminate 10 has a roughly rectangular parallelepiped shape with six faces. The structure of the laminate 10 will be described later, but it consists of multiple insulating layers stacked in the stacking direction, with a coil provided inside. The first external electrode 21 and the second external electrode 22 are electrically connected to the coil, respectively.

[0011] In the laminated coil components and laminates described herein, the length direction, height direction, and width direction are defined as the x, y, and z directions in Figure 1. Here, the length direction (x direction), height direction (y direction), and width direction (z direction) are orthogonal to each other. The length direction (x direction) is parallel to the stacking direction.

[0012] As shown in Figure 1, the laminate 10 has a first end face 11 and a second end face 12 that are opposite each other in the length direction (x direction), a first main face 13 and a second main face 14 that are opposite each other in the height direction (y direction) perpendicular to the length direction, and a first side face 15 and a second side face 16 that are opposite each other in the width direction (z direction) perpendicular to the length direction and the height direction.

[0013] Although not shown in Figure 1, it is preferable that the laminate 10 has rounded corners and edges. Corners are the parts where three faces of the laminate intersect, and edges are the parts where two faces of the laminate intersect.

[0014] The first external electrode and the second external electrode are external electrodes that extend from at least a part of the end face of the laminate to the main face of the laminate. In the multilayer coil component 1 shown in FIG. 1, the first external electrode 21 covers a part of the first end face 11 of the laminate 10, and extends from the first end face 11 to cover a part of the first main face 13. The first external electrode 21 covers a region including the ridge line portion that intersects the first main face 13 among the first end face 11.

[0015] In FIG. 1, although the height of the first external electrode 21 in the portion covering the first end face 11 of the laminate 10 is constant, as long as a part of the first end face 11 of the laminate 10 is covered, the shape of the first external electrode 21 is not particularly limited. For example, on the first end face 11 of the laminate 10, the first external electrode 21 may have a mountain-like shape that becomes higher from the end portion toward the central portion. Also, although the length of the first external electrode 21 in the portion covering the first main face 13 of the laminate 10 is constant, as long as a part of the first main face 13 of the laminate 10 is covered, the shape of the first external electrode 21 is not particularly limited. For example, on the first main face 13 of the laminate 10, the first external electrode 21 may have a mountain-like shape that becomes longer from the end portion toward the central portion.

[0016] As shown in FIG. 1, the first external electrode 21 may further extend from the first end face 11 and the first main face 13 to cover a part of the first side face 15 and a part of the second side face 16. In this case, it is preferable that the first external electrode 21 in the portion covering the first side face 15 and the second side face 16 is formed obliquely with respect to the ridge line portion intersecting the first end face 11 and the ridge line portion intersecting the first main face 13. Note that the first external electrode 21 may not be arranged to cover a part of the first side face 15 and a part of the second side face 16.

[0017] In the multilayer coil component 1 shown in FIG. 1, the second external electrode 22 covers a part of the second end face 12 of the laminate 10, and extends from the second end face 12 to cover a part of the first main face 13. Similar to the first external electrode 21, the second external electrode 22 covers a region including a ridge line portion that intersects the first main surface 13 among the second end surfaces 12.

[0018] Similar to the first external electrode 21, as long as a part of the second end surface 12 of the laminate 10 is covered, the shape of the second external electrode 22 is not particularly limited. For example, on the second end surface 12 of the laminate 10, the second external electrode 22 may have a mountain-like shape that becomes higher from the end portion toward the central portion. Also, as long as a part of the first main surface 13 of the laminate 10 is covered, the shape of the second external electrode 22 is not particularly limited. For example, on the first main surface 13 of the laminate 10, the second external electrode 22 may have a mountain-like shape that becomes longer from the end portion toward the central portion.

[0019] Similar to the first external electrode 21, the second external electrode 22 may be further arranged to cover a part of the first side surface 15 and a part of the second side surface 16 by extending from the second end surface 12 and the first main surface 13. In this case, it is preferable that the portions of the second external electrode 22 covering the first side surface 15 and the second side surface 16 are both formed obliquely with respect to the ridge line portion intersecting the second end surface 12 and the ridge line portion intersecting the first main surface 13. Note that the second external electrode 22 may not be arranged to cover a part of the first side surface 15 and a part of the second side surface 16.

[0020] Since the first external electrode 21 and the second external electrode 22 are arranged as described above, when mounting the multilayer coil component 1 on a substrate, the first main surface 13 of the laminate 10 becomes the mounting surface.

[0021] Also, different from the form shown in FIG. 1, the first external electrode may cover the entire first end surface of the laminate and extend from the first end surface to cover a part of the first main surface, a part of the second main surface, a part of the first side surface, and a part of the second side surface. Also, the second external electrode may cover the entire second end surface of the laminate and extend from the second end surface to cover a part of the first main surface, a part of the second main surface, a part of the first side surface, and a part of the second side surface. In this case, any of the first main surface, the second main surface, the first side surface, and the second side surface of the laminate becomes the mounting surface.

[0022] The size of the laminated coil component of the present invention is not particularly limited, but it is preferably 0603 size, 0402 size, or 1005 size.

[0023] The first external electrode and the second external electrode each have a base electrode containing at least Ag (silver) and glass.

[0024] The volume ratio of Ag powder to the total volume of Ag and glass is preferably 2% by volume or more and 90% by volume or less.

[0025] The first external electrode and the second external electrode may each have a multilayer structure, and may, in order from the surface side of the laminate, have, for example, the above-mentioned base electrode (base electrode layer), a nickel coating, and a tin coating.

[0026] The distance over which the glass contained in the base electrode of the first external electrode diffused from the interface between the first external electrode and the laminate to the laminate was between 2.44 μm and 6.90 μm. This increases the bonding strength between the first external electrode and the laminate. For example, in bonding strength measurement tests, a bonding strength of 3N or more can be obtained, resulting in a fracture probability of 1%. Similarly, the distance over which the glass contained in the base electrode of the second external electrode diffused from the interface between the second external electrode and the laminate to the laminate was between 2.44 μm and 6.90 μm. This increases the bonding strength between the second external electrode and the laminate. For example, in bonding strength measurement tests, a bonding strength of 3N or more can be obtained, resulting in a fracture probability of 1%. This is thought to be because, as the glass diffuses into the laminate, the interface between the first and second external electrodes and the laminate becomes stronger (the interface becomes blurred). In other words, it is thought that the glass diffused into the laminate acts as a kind of adhesive. On the other hand, if the glass is not diffused into the laminate, the first and second external electrodes are likely to peel off from the underlying electrodes.

[0027] Furthermore, even if the first and second external electrodes are made smaller, the required bonding strength between the first and second external electrodes and the laminate can be ensured. Therefore, by reducing the size of the first and second external electrodes, stray capacitance can be reduced, and the transmission coefficient S21 in the high-frequency range can be improved.

[0028] If the diffusion distance of the above-mentioned glass is less than 2.44 μm, fracture may occur between the laminate and the underlying electrode, and the bonding strength of the first or second external electrode may not be improved. If the diffusion distance of the above-mentioned glass exceeds 6.90 μm, fracture may occur in the laminate around the first or second external electrode, and the bonding strength of the first or second external electrode may not be improved.

[0029] The diffusion distance of the above-mentioned glass is preferably 2.44 μm or more and 6.90 μm or less, more preferably 2.52 μm or more and 6.72 μm or less, and even more preferably 2.6 μm or more and 5.2 μm or less. When the diffusion distance of the above-mentioned glass is between 2.44 μm and 6.90 μm, it is possible to obtain a bonding force of 3N or more that results in a fracture probability of 1%. If the diffusion distance of the above glass is between 2.6 μm and 5.2 μm, it is possible to obtain a bonding force of 4 N or more that results in a fracture probability of 1%.

[0030] The distance over which the above-mentioned glass has diffused can be determined by elemental analysis of the cross-section of the laminated coil component, for example, using wavelength dispersive X-ray spectrometry (WDX). The specific measurement method will be explained in the Examples section.

[0031] The diffusion distance of the glass can be adjusted by changing the curing temperature during the formation of the base electrode. Generally, the higher the curing temperature, the greater the diffusion distance of the glass. However, the diffusion distance of the glass is not determined solely by the curing temperature, but also varies depending on the composition of the glass and insulating layer, their combinations, and curing conditions such as curing time. Therefore, even if the curing temperature is the same, the diffusion distance may not necessarily be the same as that of the present invention.

[0032] In this context, glass diffusion into the laminate means that the glass diffuses into the insulating layer of the laminate; normally, the glass hardly diffuses into the coil (coil conductor) of the laminate.

[0033] The glass contained in the base electrodes of the first and second external electrodes preferably contains at least Bi, and the distance over which the glass has diffused is preferably the distance over which the Bi has diffused. This makes it possible to easily measure the distance over which glass has diffused using, for example, wavelength-dispersive X-ray spectroscopy (WDX) with Bi as the marker (analyte).

[0034] Furthermore, to calculate the distance over which the above-mentioned glass has diffused, it is preferable to select one element from among those with high concentrations (excluding Si and O) that are not present in the insulating layer and are present in the underlying electrode glass, and then measure it. Specifically, Bi is the most preferred element, and if Bi cannot be used for measurement, then K is preferred.

[0035] Furthermore, marker components such as Bi do not usually exist alone, but coexist with other components of the glass, forming an amorphous phase in the underlying electrode and the insulating layer of the laminate.

[0036] The glass contained in the base electrodes of the first and second external electrodes preferably contains Si in proportions of 3% to 90% by weight when converted to SiO2, B in proportions of 0.001% to 20% by weight when converted to B2O3, Bi in proportions of 0.001% to 20% by weight when converted to Bi2O3, and K in proportions of 0.001% to 20% by weight when converted to K2O.

[0037] The insulating layer preferably has a magnetic phase containing at least Fe, Ni, Zn, and Cu, and a non-magnetic phase containing at least Si. The insulating layer is a sintered body such as ferrite or glass, and may also contain resin. In this way, by constructing the insulating layer from a composite material of magnetic and non-magnetic materials, the glass contained in the underlying electrodes of the first and second external electrodes diffuses more easily into the laminate.

[0038] The magnetic phase is a phase containing a magnetic material, and the magnetic phase includes at least Fe, Ni, Zn, and Cu. The magnetic phase may also consist solely of a magnetic material. The magnetic phase may further contain Co, Bi, Sn, Mn, etc.

[0039] The magnetic material is preferably a Ni-Cu-Zn ferrite material, and the magnetic phase is preferably composed of a Ni-Cu-Zn ferrite material. The inductance of the multilayer coil component is increased when the magnetic phase is composed of a Ni-Cu-Zn ferrite material.

[0040] Ni-Cu-Zn ferrite materials may further contain additives such as Co, Bi, Sn, and Mn, as well as unavoidable impurities.

[0041] Furthermore, the magnetic phase is a phase containing Fe, Ni, Zn, and Cu when elementally analyzed. The magnetic phase may also contain Co, Bi, Sn, Mn, etc., when elementally analyzed.

[0042] The magnetic phase preferably contains Fe at a concentration of 40 mol% or more and 49.5 mol% or less (based on Fe2O3), Zn at a concentration of 2 mol% or more and 35 mol% or less (based on ZnO), Cu at a concentration of 6 mol% or more and 13 mol% or less (based on CuO), and Ni at a concentration of 10 mol% or more and 45 mol% or less (based on NiO).

[0043] The non-magnetic phase is a phase having a non-magnetic material, and contains at least Si. The non-magnetic phase may also consist solely of a non-magnetic material. Examples of nonmagnetic materials that constitute the nonmagnetic phase include glass materials, forsterite (2MgO·SiO2), and wilmite [aZnO·SiO2 (where a is between 1.8 and 2.2)]. In this specification, "a nonmagnetic phase containing at least Si" may consist only of a Si-containing phase, or it may consist of a Si-containing phase and a Si-free phase. Examples of a Si-free phase include a Si-free crystalline phase.

[0044] The non-magnetic phase preferably contains a glass material. When the non-magnetic phase contains a glass material, the glass contained in the underlying electrodes of the first and second external electrodes diffuses more easily into the laminate.

[0045] It is preferable that the glass material included in the non-magnetic phase does not contain markers (e.g., Bi or K) used to calculate the distance over which the glass has diffused.

[0046] More specifically, borosilicate glass is preferred as the glass material. Borosilicate glass preferably contains Si in proportions of 70% to 85% by weight (calculated as SiO2), B in proportions of 10% to 25% by weight (calculated as B2O3), alkali metal A in proportions of 0.5% to 5% by weight (calculated as A2O), and Al in proportions of 0% to 5% by weight (calculated as Al2O3). Examples of alkali metal A include K and Na. When using K as a marker, Na is preferred as the alkali metal A.

[0047] The nonmagnetic phase may further contain fillers such as forsterite (2MgO·SiO2) and quartz (SiO2).

[0048] The magnetic and non-magnetic phases can be distinguished as follows. First, the cross-section of the laminated coil component is exposed along the lamination direction by polishing, and then elemental mapping is performed using scanning transmission electron microscopy-energy dispersive X-ray analysis (STEM-EDX). The regions containing Fe, Ni, Zn, and Cu elements are then designated as the magnetic phase, and the regions other than the magnetic phase are designated as the non-magnetic phase, thus distinguishing between the two phases. The cross-section along the stacking direction is as shown in Figure 2, which will be described later.

[0049] Furthermore, it is preferable that the volume ratio of forsterite to the total volume of the non-magnetic phase is between 1.5% and 20% by volume. By distinguishing the region containing the element Mg, which is present in forsterite, as the region where forsterite exists, and by measuring the area ratio of the region containing forsterite to the area of ​​the nonmagnetic phase, the volume ratio of forsterite contained in the nonmagnetic phase can be determined. When 1.5% to 20% of the nonmagnetic phase is forsterite, the strength of the laminate is improved.

[0050] Next, we will explain an example of a coil embedded in a laminate that constitutes a laminated coil component. A coil is formed by electrically connecting multiple coil conductors that are stacked in the stacking direction together with an insulating layer.

[0051] Figure 2 is a schematic cross-sectional view showing an example of a laminated coil component of the present invention, Figure 3 is a schematic exploded perspective view showing the appearance of the insulating layer constituting the laminated coil component shown in Figure 2, and Figure 4 is a schematic exploded plan view showing the appearance of the insulating layer constituting the laminated coil component shown in Figure 2. Figure 2 schematically shows the insulating layer, coil conductors, connecting conductors, and the stacking direction of the laminate, and does not strictly represent the actual shape and connections. For example, the coil conductors are connected via conductors.

[0052] As shown in Figure 2, the laminated coil component 1 comprises a laminate 10 containing a coil 30 formed by electrically connecting a plurality of coil conductors 32 laminated together with an insulating layer, and a first external electrode 21 and a second external electrode 22 electrically connected to the coil 30. The laminate 10 contains a region where the coil conductor 32 is arranged and a region where the first connecting conductor 41 or the second connecting conductor 42 is arranged. The stacking direction of the laminate 10 and the axial direction of the coil 30 (shown as coil axis A in Figure 2) are parallel to the first main surface 13.

[0053] As shown in Figures 3 and 4, the laminate 10 has insulating layer 31a, insulating layer 31b, insulating layer 31c, and insulating layer 31d as insulating layer 31 in Figure 2. The laminate 10 has insulating layer 35a1, insulating layer 35a2, insulating layer 35a3, and insulating layer 35a4 as insulating layer 35aa in Figure 2. The laminate 10 has insulating layer 35b1, insulating layer 35b2, insulating layer 35b3, and insulating layer 35b4 as insulating layer 35b in Figure 2.

[0054] The coil 30, as shown in Figure 2 as the coil conductor 32, has coil conductor 32a, coil conductor 32b, coil conductor 32c, and coil conductor 32d.

[0055] The coil conductors 32a, 32b, 32c, and 32d are each arranged on the main surfaces of the insulating layers 31a, 31b, 31c, and 31d, respectively.

[0056] The lengths of coil conductors 32a, 32b, 32c, and 32d are each 3 / 4 turn lengths of coil 30. In other words, four layers of coil conductors 32 are needed to form three turns of coil 30. In the laminate 10, coil conductors 32a, 32b, 32c, and 32d are repeatedly stacked as a single unit (equivalent to three turns).

[0057] The coil conductor 32a has a line portion 36a and a land portion 37a located at the end of the line portion 36a. The coil conductor 32b has a line portion 36b and a land portion 37b located at the end of the line portion 36b. The coil conductor 32c has a line portion 36c and a land portion 37c located at the end of the line portion 36c. The coil conductor 32d has a line portion 36d and a land portion 37d located at the end of the line portion 36d.

[0058] Insulating layers 31a, 31b, 31c, and 31d are respectively arranged so as to penetrate through them in the stacking direction, via conductors 33a, 33b, 33c, and 33d.

[0059] The insulating layer 31a with coil conductor 32a and via conductor 33a, the insulating layer 31b with coil conductor 32b and via conductor 33b, the insulating layer 31c with coil conductor 32c and via conductor 33c, and the insulating layer 31d with coil conductor 32d and via conductor 33d are repeatedly stacked as a single unit (the portion enclosed by the dotted line in Figures 3 and 4). As a result, the land portions 37a of coil conductor 32a, 37b of coil conductor 32b, 37c of coil conductor 32c, and 37d of coil conductor 32d are connected via via conductors 33a, 33b, 33c, and 33d. In other words, the land portions of adjacent coil conductors in the stacking direction are connected to each other via via conductors.

[0060] The solenoid-shaped coil 30, which is built into the laminate 10, is thus constructed.

[0061] When viewed from the stacking direction, the coil 30, composed of coil conductors 32a, 32b, 32c, and 32d, may be circular or polygonal in shape. When viewed from the stacking direction, if the coil 30 is polygonal, the diameter of the circle equivalent to the area of ​​the polygon is defined as the coil diameter of the coil 30, and the axis passing through the centroid of the polygon and extending in the stacking direction is defined as the coil axis of the coil 30.

[0062] In each of the insulating layers 35a1, 35a2, 35a3, and 35a4, a via conductor 33p is arranged so as to penetrate in the stacking direction. Land portions connected to the via conductor 33p may be arranged on the main surfaces of the insulating layers 35a1, 35a2, 35a3, and 35a4.

[0063] The insulating layers 35a1 with via conductors 33p, 35a2 with via conductors 33p, 35a3 with via conductors 33p, and 35a4 with via conductors 33p are laminated so as to overlap with the coil conductor 32a and the insulating layer 31a with via conductors 33a. As a result, the via conductors 33p connect to each other to form a first connecting conductor 41, which is exposed on the first end face 11. Consequently, the first external electrode 21 and the coil 30 (coil conductor 32a) are connected to each other via the first connecting conductor 41.

[0064] The first connecting conductor 41 preferably connects the first external electrode 21 and the coil 30 in a straight line. When the first connecting conductor 41 connects the first external electrode 21 and the coil 30 in a straight line, it means that when viewed from the stacking direction in a plan view, the via conductors 33p constituting the first connecting conductor 41 overlap each other, and the via conductors 33p do not necessarily have to be aligned in a strictly straight line.

[0065] Insulating layers 35b1, 35b2, 35b3, and 35b4 are arranged such that via conductors 33q penetrate them in the stacking direction. Land portions connected to via conductors 33q may be provided on the main surfaces of insulating layers 35b1, 35b2, 35b3, and 35b4.

[0066] The insulating layers 35b1 with via conductor 33q, 35b2 with via conductor 33q, 35b3 with via conductor 33q, and 35b4 with via conductor 33q are stacked so as to overlap with the coil conductor 32d and the insulating layer 31d with via conductor 33d. As a result, the via conductors 33q connect to each other to form a second connecting conductor 42, which is exposed on the second end face 12. Consequently, the second external electrode 22 and the coil 30 (coil conductor 32d) are connected to each other via the second connecting conductor 42.

[0067] The second connecting conductor 42 preferably connects the second external electrode 22 and the coil 30 in a straight line. When the second connecting conductor 42 connects the second external electrode 22 and the coil 30 in a straight line, it means that when viewed from the stacking direction in a plan view, the via conductors 33q constituting the second connecting conductor 42 overlap each other, and the via conductors 33q do not necessarily have to be aligned in a strictly straight line.

[0068] Furthermore, if a land portion is connected to both the via conductor 33p constituting the first connecting conductor 41 and the via conductor 33q constituting the second connecting conductor 42, the shapes of the first connecting conductor 41 and the second connecting conductor 42 refer to the shapes excluding the land portions.

[0069] Figures 3 and 4 illustrate the case where the number of layers of coil conductors 32 to constitute 3 turns of coil 30 is 4, that is, the repeating shape is a 3 / 4 turn shape. However, the number of layers of coil conductors 32 to constitute 1 turn of coil is not particularly limited. For example, the number of layers of coil conductors required to constitute one turn of the coil may be 2, i.e., the repeating shape may be a 1 / 2 turn shape.

[0070] When viewed from the stacking direction in a plan view, it is preferable that the coil conductors constituting the coil overlap each other. Furthermore, when viewed from the stacking direction in a plan view, it is preferable that the shape of the coil is circular. If the coil includes a land portion, the shape excluding the land portion (i.e., the shape of the line portion) is considered the shape of the coil. Furthermore, if a land portion is connected to a via conductor that constitutes a connecting conductor, the shape of the connecting conductor will be the shape of the via conductor excluding the land portion (i.e., the shape of the via conductor).

[0071] Although the coil conductor shown in Figure 3 has a circular repeating pattern, a coil conductor with a polygonal repeating pattern, such as a square, may also be used. Furthermore, the repeating shape of the coil conductor may be a 1 / 2 turn shape instead of a 3 / 4 turn shape.

[0072] In a laminated coil component with the configuration shown in Figures 2, 3, and 4, if the size of the laminated coil component is 0603 size, it is preferable to design it as follows in order to improve the high-frequency characteristics.

[0073] The number of turns in the coil is preferably 33 turns or more and 42 turns or less. A number of turns in this range allows for a reduction in the total capacitance between coil conductors, thereby enabling a good transmission coefficient S21. Furthermore, it is preferable that the coil length is 0.49 mm or more and 0.55 mm or less.

[0074] The width of the coil conductor is preferably 45 μm or more and 75 μm or less. The width of the coil conductor is the dimension indicated by the double arrow W in Figure 2. The thickness of the coil conductor is preferably 3.5 μm or more and 6.0 μm or less. The thickness of the coil conductor is the dimension indicated by the double arrow T in Figure 2. The distance between coil conductors is preferably 3.0 μm or more and 5.0 μm or less. The distance between coil conductors is the dimension indicated by the double arrow D in Figure 2.

[0075] The diameter of the land portion of the coil conductor is preferably 30 μm or more and 50 μm or less. The diameter of the land portion of the coil conductor is the dimension shown by the double arrow R in Figure 4.

[0076] When the first main surface of the laminate is the mounting surface, the lengths of the first external electrode and the second external electrode covering the first main surface of the laminate are preferably 0.20 mm or less, and preferably 0.10 mm or more. The lengths of the first and second external electrodes covering the first main surface of the laminate are the dimensions indicated by the double arrow E1 in Figure 2.

[0077] The laminated coil component of the present invention is manufactured, for example, by the following method.

[0078] <Magnetic material manufacturing process> Fe2O3, ZnO, CuO, and NiO are weighed in predetermined ratios. Each oxide may contain unavoidable impurities. Next, these weighed materials are mixed wet and then pulverized to produce a slurry. Additives such as Mn3O4, Bi2O3, Co3O4, SiO2, and SnO2 may be added at this stage. The resulting slurry is then dried and calcined. The calcination temperature is, for example, 700°C or higher and 800°C or lower. The calcination time is, for example, 2 hours or higher and 5 hours or lower. In this way, powdered ferrite material is produced as a magnetic material.

[0079] The ferrite material preferably contains 40 mol% to 49.5 mol% of Fe2O3, 2 mol% to 35 mol% of ZnO, 6 mol% to 13 mol% of CuO, and 10 mol% to 45 mol% of NiO.

[0080] <Non-magnetic material manufacturing process> Weigh the non-magnetic material powder. Prepare a glass powder containing alkali metals such as potassium, boron, silicon, and aluminum in predetermined proportions as borosilicate glass. Also, prepare forsterite powder as a filler. Quartz powder may also be prepared as a filler.

[0081] Borosilicate glass preferably contains Si in a proportion of 70% to 85% by weight when converted to SiO2, B in a proportion of 10% to 25% by weight when converted to B2O3, alkali metal A in a proportion of 0.5% to 5% by weight when converted to A2O, and Al in a proportion of 0% to 5% by weight when converted to Al2O3.

[0082] The non-magnetic material preferably contains forsterite powder as a filler in an amount of 1.5% or more and 20% or less by volume.

[0083] <Conductive paste manufacturing process> Ag powder is prepared, mixed with a predetermined amount of solvent (such as eugenol), resin (such as ethylcellulose), and dispersant in a planetary mixer, and then dispersed in a three-roll mill to produce a conductive paste for the internal conductor.

[0084] <Green sheet manufacturing process> Magnetic and non-magnetic materials are weighed in a predetermined ratio. Next, these weighed materials are mixed with an organic binder such as polyvinyl butyral resin, an organic solvent such as ethanol or toluene, a plasticizer, etc., and then pulverized to produce a slurry. The resulting slurry is then formed into a sheet of a predetermined thickness using a doctor blade method or the like, and then punched out into a predetermined shape, such as a rectangle, to produce a green sheet. The thickness of the green sheet is preferably 20 μm or more and 30 μm or less.

[0085] The volume ratio of the magnetic material to the total volume of the magnetic and non-magnetic materials is preferably 10% by volume or more and 80% by volume or less, more preferably 15% by volume or more and 70% by volume or less, and even more preferably 20% by volume or more and 60% by volume or less. If the volume ratio of magnetic material to the total volume of magnetic and non-magnetic materials is less than 10% by volume, the strength of the laminate may be weakened. If the volume ratio of magnetic material to the total volume of non-magnetic material exceeds 80% by volume, the magnetic and non-magnetic materials may become difficult to sinter.

[0086] <Conductor pattern formation process> First, a via hole is formed by irradiating a designated area on the green sheet with a laser.

[0087] Next, conductive paste is applied to the surface of the green sheet by screen printing or the like, filling the via holes. This forms a conductor pattern for via conductors in the via holes of the green sheet, and a conductor pattern for coil conductors connected to the via conductor pattern on the surface. In this way, a coil sheet is produced in which the conductor pattern for coil conductors and the conductor pattern for via conductors are formed on the green sheet. Multiple coil sheets are produced, and each coil sheet is formed with a conductor pattern for coil conductors corresponding to the coil conductors shown in Figures 3 and 4, and a conductor pattern for via conductors corresponding to the via conductors shown in Figures 3 and 4.

[0088] Furthermore, via sheets are fabricated separately from the coil sheets by filling via holes with conductive paste using a screen printing method or the like, thereby forming a conductive pattern for via conductors on the green sheet. Multiple via sheets are also fabricated, and a conductive pattern for via conductors corresponding to the via conductors shown in Figures 3 and 4 is formed on each via sheet.

[0089] <Laminated block manufacturing process> A laminated block is fabricated by stacking coil sheets and via sheets in the stacking direction in the order corresponding to Figures 3 and 4, and then heat-pressing them together.

[0090] <Laminate and coil manufacturing process> First, individual chips are produced by cutting the laminated block into predetermined sizes using a dicer or similar tool.

[0091] Next, the individual chips are fired. The firing temperature should be, for example, between 900°C and 920°C. The firing time should be, for example, between 2 hours and 4 hours.

[0092] By firing the individual chips, the green sheets of the coil sheet and via sheet become insulating layers. As a result, a laminate is produced in which multiple insulating layers are stacked in the stacking direction, in this case, the length direction. Magnetic and non-magnetic phases are formed in the laminate.

[0093] By firing the individual chips, the conductor patterns for coil conductors and via conductors on the coil sheet become coil conductors and via conductors, respectively. As a result, a coil is fabricated in which multiple coil conductors are stacked in the stacking direction and electrically connected via via conductors.

[0094] Based on the above, a laminate and a coil provided inside the laminate are manufactured. The lamination direction of the insulating layer and the direction of the coil axis of the coil are parallel to the first main surface, which is the mounting surface of the laminate, and in this case, they are parallel along the length direction.

[0095] By firing the individual chips, the conductor patterns for via conductors on the via sheet become via conductors. As a result, a first connecting conductor and a second connecting conductor are produced, each consisting of multiple via conductors stacked and electrically connected in the longitudinal direction. The first connecting conductor is exposed from the first end face of the stack. The second connecting conductor is exposed from the second end face of the stack.

[0096] For the laminate, for example, the corners and edges may be rounded by barrel polishing.

[0097] <External electrode formation process> First, a conductive paste containing Ag powder and Bi-containing glass is applied to the first and second end faces of the laminate.

[0098] The volume ratio of Ag powder to the total volume of Ag powder and glass is preferably 2% by volume or more and 90% by volume or less.

[0099] The glass contained in the conductive paste preferably contains Bi in proportions of 0.001% to 20% by weight when converted to Bi2O3, Si in proportions of 3% to 90% by weight when converted to SiO2, B in proportions of 0.001% to 20% by weight when converted to B2O3, and K in proportions of 0.001% to 20% by weight when converted to K2O.

[0100] Next, the obtained coating films are baked to form base electrodes on the surface of the laminate. More specifically, base electrodes are formed extending from the first end face of the laminate to a portion of the first main surface, the first side surface, and the second side surface. Additionally, base electrodes are formed extending from the second end face of the laminate to a portion of the first main surface, the first side surface, and the second side surface. Here, the baking of each coating film is carried out in an oxidizing atmosphere such as air, but a reducing atmosphere may also be used.

[0101] The baking temperature for each coating film is preferably 750°C or higher and 870°C or lower, more preferably 800°C or higher and 850°C or lower, and even more preferably 800°C or higher and 830°C or lower.

[0102] The curing time for each coating is preferably 10 minutes or more and 120 minutes or less, more preferably 20 minutes or more and 90 minutes or less, and even more preferably 30 minutes or more and 60 minutes or less.

[0103] Subsequently, a nickel coating and a tin coating are sequentially formed on the surface of each base electrode by electroplating or the like.

[0104] In this way, a first external electrode electrically connected to the coil via a first connecting conductor and a second external electrode electrically connected to the coil via a second connecting conductor are formed. Based on the above, a laminated coil component is manufactured.

[0105] This specification discloses the following:

[0106] <1> The laminate comprises a plurality of insulating layers stacked in the stacking direction and having a coil provided inside, and an external electrode provided on the surface of the laminate and electrically connected to the coil. The laminate has a first end face and a second end face opposite each other in the longitudinal direction, a first main face and a second main face opposite each other in the height direction perpendicular to the longitudinal direction, and a first side face and a second side face opposite each other in the width direction perpendicular to the longitudinal direction and the height direction, The external electrode comprises a first external electrode extending from at least a portion of the first end face of the laminate to a portion of the first main surface, and a second external electrode extending from at least a portion of the second end face of the laminate to a portion of the first main surface. The external electrode has a base electrode containing at least Ag and glass, A laminated coil component, wherein the distance over which the glass diffuses from the interface between the external electrode and the laminate to the laminate is 2.44 μm or more and 6.90 μm or less.

[0107] <2> The stacking direction of the laminate and the coil axis of the coil are parallel to the first main surface. <1> The laminated coil component described above.

[0108] <3> The glass contains at least Bi, The distance over which the glass diffused is the same as the distance over which the Bi diffused. <1> or <2> The laminated coil component described above.

[0109] <4> The size of the aforementioned laminated coil component is 0603 size, 0402 size, or 1005 size. <1> from <3> A laminated coil component as described in any one of the following.

[0110] <5> The insulating layer comprises a magnetic phase containing at least Fe, Ni, Zn, and Cu, and a non-magnetic phase containing at least Si. <1> from <4> A laminated coil component as described in any one of the following. [Examples]

[0111] The following are examples that more specifically disclose the laminated coil component of the present invention. However, the present invention is not limited to these examples.

[0112] [Examples 1-6 and Comparative Examples 1-3] The laminated bodies for the laminated coil components of Examples 1-6 and Comparative Examples 1-3 were manufactured by the following method.

[0113] <Magnetic material manufacturing process> The main components were weighed out in the following proportions: Fe2O3 48.0 mol%, ZnO 30.0 mol%, NiO 14.0 mol%, and CuO 8.0 mol%. Next, these weighed materials, along with pure water and a dispersant, were placed in a ball mill with PSZ media and mixed, then pulverized to produce a slurry. The resulting slurry was dried and then calcined at 800°C for 2 hours. In this way, a powdered ferrite material was prepared as a magnetic material.

[0114] <Non-magnetic material manufacturing process> Borosilicate glass powder containing Si, B, K, and Al in predetermined proportions, along with forsterite powder and quartz powder as fillers, were prepared. The borosilicate glass powder, forsterite powder, and quartz powder were weighed in a volume ratio of borosilicate glass:forsterite:quartz = 93:6:1. Next, these weighed materials, along with pure water and a dispersant, were placed in a ball mill with PSZ media and mixed, then ground to produce a slurry. The resulting slurry was then dried to produce a powdered nonmagnetic material.

[0115] <Green sheet manufacturing process> Magnetic and non-magnetic materials were weighed so that their volume ratio was 60:40. Next, these weighed materials, along with polyvinyl butyral resin as an organic binder and ethanol and toluene as organic solvents, were placed in a ball mill with PSZ media and mixed, then ground to produce a slurry. The resulting slurry was then formed into a sheet of a predetermined thickness using a doctor blade method, and then punched into a predetermined shape to produce a green sheet.

[0116] <Conductor pattern formation process> A conductive paste was prepared by mixing Ag powder, a predetermined amount of solvent (eugenol), resin (ethylcellulose), and a dispersant in a planetary mixer, and then dispersing the mixture in a three-roll mill. After forming via holes in predetermined locations on a green sheet and filling them with conductive paste to form via conductors, a coil conductor pattern was printed to obtain a coil sheet. Separately, via holes were formed by irradiating predetermined locations on the green sheet with a laser. Conductive paste was then filled into the via holes to form via conductors and obtain a via sheet.

[0117] <Laminated block manufacturing process> A laminated block was fabricated by stacking coil sheets and via sheets in the stacking direction in the order corresponding to Figures 3 and 4, and then heat-pressing them together.

[0118] <Laminate and coil manufacturing process> Individual chips were produced by cutting the laminated block with a dicer. Subsequently, the individual chips were fired at 910°C for 4 hours to form a laminate. A magnetic phase and a non-magnetic phase were formed in the laminate.

[0119] <External electrode formation process> A conductive paste for external electrodes containing Ag powder and Bi-containing glass was poured into a coating tank to form a coating of a predetermined thickness. The areas of the laminate where the external electrodes would be formed were then immersed in this coating. After immersion, the base electrode for the external electrode was formed by baking it in the air at the temperature shown in Table 1 for 1 hour. The thickness of the base electrode was approximately 5 μm. In the base electrode after baking, the weight ratio of Bi to Si was Bi(Bi2O3):Si(SiO2) = 0.0001 to 1:1, converted to Bi2O3 and SiO2, respectively. Next, using electroplating, nickel and tin coatings were sequentially formed on the base electrode as plating electrodes to create the external electrode.

[0120] Based on the above, laminated coil components of Examples 1 to 6 and Comparative Examples 1 to 3 were manufactured. The dimensions of the fabricated laminated coil component were 0.6 mm in length, 0.3 mm in height, and 0.3 mm in width.

[0121] <Measuring the diffusion distance of glass> Figure 5 is a schematic diagram illustrating the method for measuring the diffusion distance of glass (Bi). The prepared samples (laminated coil components of Examples 1-6 and Comparative Examples 1-3) were placed upright so that their width direction (z direction) was perpendicular, and the area around the sample was solidified with resin. The sample was polished using a polishing machine in the width direction to a depth where the approximate center of the width direction was exposed. The distance over which the glass contained in the base electrode of the external electrode, in this case Bi, a component of glass, diffused from the interface between the external electrode and the laminate was measured using wavelength-dispersive X-ray spectroscopy (WDX) on the cross-section of the obtained sample, as follows. That is, as shown in Figure 5, in the x direction, a 20 μm section was analyzed from approximately 0 μm on the external electrode 120 side to approximately 20 μm on the laminate 110 side, with the interface between the external electrode 120 (base electrode 120a) and the laminate 110 (at a position of 10 μm) in between. In the y direction, a 20 μm section was analyzed for the element Bi in a square region. In detail, the aforementioned square region was divided into 256 x 256 unit square regions, and the amount of Bi element detected was measured for each unit square. Then, for every other unit square in the x-direction, the average of the amount of Bi element detected for 256 unit squares in the y-direction was taken and defined as the amount of Bi element detected in the x-direction. Note that the measurement region in the y-direction was limited to the area where the interface between the external electrode and the laminate exists. The area in the y-direction where no interface exists was excluded from the measurement results. The distance from the interface to the position where the X-ray intensity becomes flat (background) was defined as the diffusion distance of the glass (Bi). Here, the 5-point moving average of the amount of Bi element detected in the x-direction was calculated, and the point where the difference from the previous point for the first time was within 3% for three consecutive points in the +x direction (direction from the external electrode to the laminate) was defined as the background. The results are shown in Table 1 below. The interface location can be determined from the observed image of the chip cross-section. The interface location naturally has a range (varies) in the x-direction in most cases, but in such cases, the average of the x-coordinate values ​​of the interface determined by each y-coordinate value can be obtained. For example, it is preferable to divide the chip cross-sectional image into the same unit square region (a region obtained by dividing a 20 μm x 20 μm square area into 256 x 256 sections) as for the detection of Bi element by WDX described above, perform image analysis, and calculate the average of the x-coordinate values ​​of the interface determined by each y-coordinate value. In this measurement, the interface location and the peak location of the X-ray intensity coincided, so for convenience, the location where the X-ray intensity peaked was defined as the interface between the substrate electrode and the laminate.

[0122] <Measurement of bonding strength of external electrodes> Fifteen samples were prepared for each of the fabricated examples (Laminated coil components of Examples 1-6 and Comparative Examples 1-3). Each sample was mounted on a glass epoxy substrate, and the bonding strength was measured using a bond tester. The results were plotted using a Weibull plot, and the bonding strength at which the failure probability was 1% was determined. In addition, the failure modes were evaluated for the 15 evaluated samples, and the dominant mode was assessed. The failure modes were divided into failure between the laminate and the base electrode (Ag), failure between the base electrode (Ag) and the plated electrode, failure in the laminate around the external electrode, and failure at the fillet. The results are shown in Table 1 below.

[0123] [Table 1]

[0124] Furthermore, Figure 6 shows scatter plots of the diffusion distance of glass (Bi) and the bonding force at which the fracture probability is 1% for the laminated coil components of Examples 1-6 and Comparative Examples 1-3. Figure 6 shows approximation lines passing through four points for Comparative Example 2 and Examples 1-3, and approximation lines passing through four points for Examples 4-6 and Comparative Example 3. From these approximation lines, it can be seen that the bonding force at which the fracture probability is 1% is 3N or more when the diffusion distance of glass (Bi) is between 2.44 μm and 6.90 μm.

[0125] As shown in Table 1 and Figure 6, in Examples 1 to 6, where the diffusion distance of Bi, i.e., glass, is 2.44 μm or more and 6.90 μm or less, a bonding force of 3N or more was obtained, resulting in a fracture probability of 1%. The fracture mode was mainly fracture in the laminate or fillet around the external electrode, indicating that sufficient bonding force was achieved. In Examples 1-6 and Comparative Examples 1-3, the diffusion distance of glass (Bi) is the average value of 15 samples.

[0126] Furthermore, while it is generally true that a laminated coil component can withstand market mounting environments if the bonding force at which the failure probability is 1% exceeds 2N, here we evaluated the bonding strength using 3N, which is 1.5 times that value, as a margin. [Explanation of Symbols]

[0127] 1. Laminated coil component 10, 110 laminate 11 First end surface 12 Second end face 13. First Main Surface 14. Second Main Surface 15 First aspect 16 Second aspect 21 1st external electrode 22 2nd external electrode 30 coils 31, 31a, 31b, 31c, 31d, 35a, 35a1, 35a2, 35a3, 35a4, 35b, 35b1, 35b2, 35b3, 35b4 insulating layer 32, 32a, 32b, 32c, 32d Coil conductors 33a, 33b, 33c, 33d, 33p, 33q via conductors 36a, 36b, 36c, 36d line section 37a, 37b, 37c, 37d Land section 41 First connecting conductor 42 Second connecting conductor 120 External electrode 120a Underlay electrode

Claims

1. The laminate comprises a plurality of insulating layers stacked in the stacking direction and having a coil provided inside, and an external electrode provided on the surface of the laminate and electrically connected to the coil. The laminate has a first end face and a second end face opposite each other in the longitudinal direction, a first main face and a second main face opposite each other in the height direction perpendicular to the longitudinal direction, and a first side face and a second side face opposite each other in the width direction perpendicular to the longitudinal direction and the height direction. The external electrode comprises a first external electrode extending from at least a portion of the first end face of the laminate to a portion of the first main surface, and a second external electrode extending from at least a portion of the second end face of the laminate to a portion of the first main surface. The external electrode has a base electrode containing at least Ag and glass, A laminated coil component, wherein the distance over which the glass diffuses from the interface between the external electrode and the laminate to the laminate is 2.44 μm or more and 6.90 μm or less.

2. The laminated coil component according to claim 1, wherein the lamination direction of the laminate and the coil axis of the coil are parallel to the first main surface.

3. The glass contains at least Bi, The laminated coil component according to claim 1 or 2, wherein the distance over which the glass has diffused is the distance over which Bi has diffused.

4. The laminated coil component according to claim 1 or 2, wherein the size of the laminated coil component is 0603 size, 0402 size, or 1005 size.

5. The laminated coil component according to claim 1 or 2, wherein the insulating layer comprises a magnetic phase containing at least Fe, Ni, Zn, and Cu, and a non-magnetic phase containing at least Si.

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