Stacked inductor component and method for manufacturing stacked inductor component

Abstract

The present invention provides a laminated inductor component that can reduce the resistance of a coil without using voids. The component includes a substrate (11) as an insulator and a coil (12) formed by electrically connecting a plurality of coil conductor layers (12a) to (12c) that extend along a plane within the substrate (11). The coil conductor layers (12a) to (12c) include a metal part (M) and a glass part (GLA), and the glass part (GLA) includes an embedded glass (GLAi) embedded in the metal part (M).

Description

[0001] This application is a divisional application of an application with an application number of 201811351471.1, a filing date of November 14, 2018, and an invention title of "Stacked Inductor Component and Method for Manufacturing Stacked Inductor Component". Technical Field

[0002] The present invention relates to a stacked inductor component formed by laminating an insulating layer and a coil conductor layer, and a method for manufacturing the stacked inductor component. Background Art

[0003] In recent years, with the high-frequencyization of the carrier frequency of communication devices such as mobile phones, a plurality of spiral inductors corresponding to high frequencies in the GHz band are used in the signal transmission section and the signal reception section of these devices.

[0004] As one type of such an inductor, a stacked inductor component having a substrate as an insulator and a plurality of coil conductor layers extending along a plane in the substrate is actually used. By electrically connecting each coil conductor layer through a via hole formed in the substrate, a coil is formed in the substrate. The coil conductor layer is formed, for example, by firing a conductive paste containing metal in resin, sputtering, electroplating, or the like.

[0005] In the above-described stacked inductor component, in order to improve the performance of a communication device operating at high frequencies, it is necessary to ensure a high Q value (quality factor). In order to increase the Q value, it is necessary to improve the low resistance with respect to the coil and the efficiency of the inductance obtainable from the outer shape of the substrate (inductance acquisition efficiency).

[0006] Here, since the high-frequency current flowing through the coil conductor layer flows near the surface of the coil conductor layer due to the skin effect, in order to reduce the resistance of the coil with respect to the high-frequency current, it is effective to increase the surface area of the coil conductor layer.

[0007] In Patent Document 1, a stacked inductor component is disclosed. By forming a vacancy in the conductive paste before the resin vaporizes and scatters during firing, and forming a sintered metal around the resin, the surface area of the coil conductor layer is increased to achieve low resistance of the coil.

[0008] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2014-45081

[0009] Figure 11 Fig. 30 shows the stacked inductor component disclosed in Patent Document 1. In this inductor component 1, the surface area of the coil conductor layer 2 (coil conductor) is increased by forming a vacancy 3 therein to achieve low resistance of the coil.

[0010] On the other hand, since the vaporization temperature of the resin in the conductive paste is generally lower than the sintering completion temperature of the metal powder which is the main component of the conductive paste, it is difficult to form a shape with voids 3 in the metal part of the coil conductor layer 2 after firing.

[0011] In addition, since the sintering of the material of the substrate 4 covering the coil conductor layer 2, such as glass powder, progresses faster than that of the metal powder, the gas generated in the conductive paste is difficult to disperse toward the outside of the substrate 4 and is likely to stay near the outer periphery of the coil conductor layer 2, thus easily forming voids 3 in this region.

[0012] In the laminated inductor component 1 formed in this way, due to the voids 3 formed near the outer periphery of the coil conductor layer 2, its outer periphery will not actually become a smooth shape as shown in Figure 11 (a), Figure 11 (b), but will have strong irregularities. In the coil conductor layer 2 with such a shape, the smooth flow of current is hindered, and losses caused by local concentration of current, generation of eddy currents due to the disorder of the magnetic flux direction, etc. increase, and the acquisition efficiency of inductance decreases. In addition, the voids 3 formed near the outer periphery of the coil conductor layer 2 reduce the strength of the coil conductor layer 2 and may also cause the coil to break or have a high resistance. That is, if one wants to reduce the resistance of the coil by using the voids 3 in the coil conductor layer 2 as in Patent Document 1, there is a possibility of various problems occurring. SUMMARY OF THE INVENTION

[0013] The present invention has been completed in view of such a situation, and its object is to provide a laminated inductor component that can reduce the resistance of the coil without using voids.

[0014] The laminated inductor component for solving the above problems includes: a substrate, which is an insulator; and a coil, which is formed by electrically connecting a plurality of coil conductor layers extending along a plane in the above substrate, the coil conductor layer including a metal part and a glass part, and the glass part including an embedded glass contained in the metal part.

[0015] In this structure, the surface area of the coil conductor layer is increased by the embedded glass.

[0016] In addition, in the above laminated inductor component, it is preferable that the glass part includes an exposed glass exposed from the metal part, and in a cross section of the coil conductor layer orthogonal to the extending direction, there is a cross section including the proportion of the embedded glass in the glass part less than 50% in terms of area ratio.

[0017] In this structure, the surface area of the coil conductor layer is also increased by the exposed glass.

[0018] In addition, in the above-described stacked inductor component, it is preferable that in a cross-section orthogonal to the extending direction of the coil conductor layer, a cross-section including the proportion of the glass contained in the glass portion is 50% or more in terms of area ratio.

[0019] In this structure, the surface area of the coil conductor layer is increased, and the smoothing of the outer periphery of the metal portion of the coil conductor layer is promoted.

[0020] In addition, in the above-described stacked inductor component, it is preferable that in a cross-section orthogonal to the extending direction of the coil conductor layer, a cross-section including the proportion of the glass contained in the glass portion is 100% in terms of area ratio.

[0021] In this structure, the smoothing of the outer periphery of the metal portion of the coil conductor layer is further promoted.

[0022] In addition, in the above-described stacked inductor component, it is preferable that in a cross-section orthogonal to the extending direction of the coil conductor layer, a cross-section including the proportion of the glass contained relative to the coil conductor layer is 1.0% or more and 20.0% or less in terms of area ratio.

[0023] In this structure, the smooth flow of current in the coil conductor layer can be promoted, and the surface area of the coil conductor layer can be increased.

[0024] In addition, in the above-described stacked inductor component, it is preferable that the substrate contains glass. If the glass of the substrate within 10 μm around the coil conductor layer is defined as the peripheral glass and the glass of the substrate further outside than the peripheral glass is defined as the outer peripheral glass, then the softening point of the peripheral glass is lower than the softening point of the outer peripheral glass.

[0025] In this structure, since the coil conductor layer is formed in a state surrounded by the relatively easily softened peripheral glass, the smoothing of the outer periphery of the coil conductor layer is promoted.

[0026] In addition, in the above-described stacked inductor component, it is preferable that the softening point of the peripheral glass is equal to or lower than the softening point of the glass contained.

[0027] In this structure, since the coil conductor layer is formed in a state surrounded by the relatively easily softened peripheral glass, the smoothing of the outer periphery of the coil conductor layer is promoted.

[0028] In addition, in the above-described stacked inductor component, it is preferable that the base body contains glass. If the glass of the base body within 10 μm around the coil conductor layer is defined as the peripheral glass and the glass of the base body further outside than the peripheral glass is defined as the outer peripheral glass, the peripheral glass contains a filling element of any one of Bi, Li, Na, K, Mg, Ca, Sr, Ba, Co, Zn, B, Pb, Al, Zr, P, and V, and the concentration of the filling element in the peripheral glass is higher than that in the outer peripheral glass.

[0029] In this structure, since the coil conductor layer is formed in a state surrounded by the peripheral glass that is relatively easily softened, the smoothing of the outer periphery of the coil conductor layer is promoted.

[0030] In addition, in the above-described stacked inductor component, it is preferable that the concentration of Si in the peripheral glass is lower than the concentration of Si in the outer peripheral glass.

[0031] In this structure, since the coil conductor layer is formed in a state surrounded by the peripheral glass that is relatively easily softened, the smoothing of the outer periphery of the coil conductor layer can be promoted.

[0032] In addition, in the above-described stacked inductor component, it is preferable that if the glass located at the outermost side in the direction orthogonal to the plane in which the coil conductor layer extends in the base body is defined as the outer layer glass, the concentration of Si in the peripheral glass is lower than the concentration of Si in the outer layer glass.

[0033] In this structure, since the clarity of the outermost part of the base body is improved and the visibility of the alignment mark is improved, the singulation accuracy is improved.

[0034] In addition, in the above-described stacked inductor component, it is preferable that if the glass located at the outermost side in the direction orthogonal to the plane in which the coil conductor layer extends in the base body is defined as the outer layer glass, the concentration of Si in the peripheral glass is higher than the concentration of Si in the outer layer glass.

[0035] In this structure, the strength of the base body is improved.

[0036] In addition, in the above-described stacked inductor component, it is preferable that the metal parts included in the plurality of coil conductor layers form a plurality of crystals, and the average particle diameter of the plurality of crystals is 0.5 μm or more and 15.0 μm or less.

[0037] In this structure, since the grain boundaries that inhibit the flow of electrons are reduced, the low resistance of the coil conductor layer can be achieved, and the excessive enlargement of the crystals can be suppressed and the smoothing of the outer periphery of the coil conductor layer can be promoted.

[0038] In addition, in the above-described stacked inductor component, it is preferable that the base body is a sintered body.

[0039] In this structure, the strength of the substrate is increased.

[0040] In addition, in the above-described laminated inductor component, it is preferable to further include a first external electrode and a second external electrode which are arranged along the outer surface of the substrate and are electrically connected to the first end and the second end of the coil respectively. The outer surface includes a mounting surface on which both the first external electrode and the second external electrode are arranged, a first end surface on which only the first external electrode is arranged, and a second end surface on which only the second external electrode is arranged. The mounting surface, the first end surface, and the second end surface are orthogonal to the plane in which the coil conductor layer extends.

[0041] In this structure, the fixing force during substrate mounting is increased, and a decrease in the Q value due to eddy current loss can be suppressed.

[0042] The laminated inductor component for solving the above problems includes: a substrate which is an insulator; and a coil which is formed by electrically connecting a plurality of coil conductor layers extending along a plane in the substrate. The coil conductor layer includes a metal part and a glass part. The substrate includes glass. If the glass of the substrate within 10 μm around the coil conductor layer is defined as peripheral glass and the glass of the substrate further outside than the peripheral glass is defined as outer peripheral glass, the softening point of the peripheral glass is lower than the softening point of the outer peripheral glass.

[0043] In this structure, since the coil conductor layer is formed in a state of being surrounded by the relatively easily softened peripheral glass, the smoothing of the outer periphery of the coil conductor layer can be promoted.

[0044] In addition, in the above-described laminated inductor component, it is preferable that the softening point of the peripheral glass is equal to or lower than the softening point of the glass part.

[0045] In this structure, since the coil conductor layer is formed in a state of being surrounded by the relatively easily softened peripheral glass, the smoothing of the outer periphery of the coil conductor layer can be promoted.

[0046] The manufacturing method of the stacked inductor component for solving the above problems includes: a step of forming a laminate in which coil conductor patterns made of the conductive paste are arranged between a plurality of insulating paste layers made of the insulating paste, using an insulating paste containing glass powder and a conductive paste containing metal powder and glass powder; and a step of firing the laminate to sinter the metal powder and the glass powder into a metal part and a glass part respectively. The glass powder contained in the conductive paste uses a material with a softening point lower than the glass powder contained in the insulating paste. In the step of firing the laminate, an inclusion glass formed by sintering the glass powder contained in the conductive paste inside the metal part and a peripheral glass formed by extruding the glass powder contained in the conductive paste around the metal part and sintering it are formed.

[0047] In this method, through the inclusion glass and the peripheral glass formed in the step of firing the laminate, the surface area of the coil conductor layer sintered from the coil conductor pattern increases, and the smoothing of the outer periphery is promoted.

[0048] According to the stacked inductor component of the present invention, the coil can be made to have a low resistance without using voids. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a perspective view showing a stacked inductor component.

[0050] Figure 2 It is an exploded perspective view showing an outline of each part of the stacked inductor component.

[0051] Figure 3 (a) to Figure 3 (d) are explanatory diagrams showing the firing process of the coil conductor.

[0052] Figure 4 (a) to Figure 4 (d) are explanatory diagrams showing the firing process of the coil conductor.

[0053] Figure 5 (a) to Figure 5 (d) are schematic diagrams showing the firing process of the coil conductor.

[0054] Figure 6 It is a schematic diagram showing the coil conductor in the firing process.

[0055] Figure 7 It is an explanatory diagram showing the calculation method of the diameter of the crystal of the coil conductor.

[0056] Figure 8 It is a schematic diagram showing the coil conductor in the firing process.

[0057] Figure 9It is a schematic cross-sectional view showing the fired laminate.

[0058] Figure 10 It is a schematic top view showing the fired laminate.

[0059] Figure 11 (a), Figure 11 (b) is a cross-sectional view showing a conventional laminated coil component. Detailed implementation mode

[0060] Hereinafter, an embodiment as one mode of the present invention will be described with reference to the drawings.

[0061] Figure 1 The laminated inductor component 10 shown includes a substrate 11 as an insulator, a coil 12 formed in the substrate 11, and a first external electrode 13x and a second external electrode 13y that are arranged along the outer surface of the substrate 11 and are electrically connected to the first end and the second end of the coil 12, respectively.

[0062] The substrate 11 is formed by laminating a plurality of insulator layers, and the coil 12 is formed by electrically connecting a plurality of coil conductor layers extending along a plane corresponding to the main surface of the insulator layer in the substrate 11 via via holes 14.

[0063] In addition, the outer surface of the substrate 11 includes a mounting surface 11a on which both the first external electrode 13x and the second external electrode 13y are arranged, a first end surface 11b on which only the first external electrode 13x is arranged, and a second end surface 11c on which only the second external electrode 13y is arranged. The mounting surface 11a, the first end surface 11b, and the second end surface 11c are orthogonal to the main surface of the insulator layer. That is, as Figure 1 shown, in the laminated inductor component 10, the mounting surface 11a, the lamination direction of the insulator layers, and the winding axis of the coil 12 are parallel.

[0064] Figure 2 shows an overview of each part of the laminated inductor component 10. The insulator layers 15a, 15b, 16a - 16c, 18 that make up the substrate 11, the coil conductor layers 12a - 12c that make up the coil 12, and the external electrode layers 13a - 13e that make up the first external electrode 13x and the second external electrode 13y are laminated, for example, from Figure 2 below the paper surface to above the paper surface. In Figure 1 , for example, they are laminated in sequence from the front side to the back side of the substrate 11. In addition, the lamination direction may be the opposite direction in Figure 1 , Figure 2 .

[0065] Hereinafter, use Figure 2, which shows an example of a manufacturing method of the stacked inductor component 10. First, an insulating paste containing glass powder is repeatedly coated on a substrate (not shown) by screen printing to sequentially form a marking insulating paste layer 18 and an outer layer insulating paste layer 15a. Next, a photosensitive conductive paste containing metal powder and glass powder is coated on the outer layer insulating paste layer 15a, and is patterned by a photolithography process to form a pair of external electrode patterns 13a.

[0066] One external electrode pattern 13a is formed in an L shape from the position corresponding to the mounting surface 11a of the outer layer insulating paste layer 15a to the position corresponding to the first end face 11b, and the other external electrode pattern 13a is formed in an L shape from the position corresponding to the mounting surface 11a of the outer layer insulating paste layer 15a to the position corresponding to the second end face 11c side.

[0067] Next, a photosensitive insulating paste containing glass powder is coated on the outer layer insulating paste layer 15a on which the external electrode pattern 13a is formed, and is patterned by a photolithography process to form an insulating paste layer 16a having an opening 17 formed in the external electrode pattern 13a.

[0068] Next, the above-mentioned conductive paste is coated on the insulating paste layer 16a and in the opening 17, and is patterned by a photolithography process to form a pair of external electrode patterns 13b and a coil conductor pattern 12a extending approximately one week along the main surface of the insulating paste layer 16a. The coil conductor pattern 12a is formed integrally with one of the external electrode patterns 13b and is electrically connected thereto. The external electrode pattern 13b is stacked on the external electrode pattern 13a via the opening 17 and is electrically connected to each other.

[0069] Next, the above-mentioned photosensitive insulating paste is coated on the insulating paste layer 16a on which the external electrode pattern 13b and the coil conductor pattern 12a are formed, and is patterned by a photolithography process to form an insulating paste layer 16b, which has the same opening 17 and via holes 14 as the insulating paste layer 16a. The via holes 14 are formed at the end portions on the side not connected to the external electrode pattern 13b of the coil conductor pattern 12a.

[0070] Next, on the insulating paste layer 16b, the above-mentioned conductive paste is coated in the opening 17 and in the via holes 14, and is patterned by a photolithography process to form a pair of external electrode patterns 13c and a coil conductor pattern 12b extending approximately one week along the main surface of the insulating paste layer 16b. One end portion of the coil conductor pattern 12b is electrically connected to the lower layer coil conductor pattern 12a via the conductive paste coated in the via holes 14. In addition, the external electrode pattern 13c is stacked on the external electrode pattern 13b via the opening 17 and is electrically connected to each other.

[0071] By appropriately combining and repeatedly performing the same processes as above, multiple insulating paste layers 16a to 16d and coil conductor patterns 12a to 12c connected via the opening 17 are laminated. In addition, the coil conductor pattern 12c on the uppermost layer is formed integrally with another external electrode pattern 13d on the opposite end side of the via hole 14 and is electrically connected thereto.

[0072] Then, an insulating paste is applied onto the insulating paste layer 16d on which the external electrode pattern 13e is formed, and an outer layer insulating paste layer 15b and a marking insulating paste layer 18 are sequentially formed to generate a laminate.

[0073] In addition, multiple Figure 2 The laminated inductor component 10 shown can also be formed simultaneously. In this case, a mother laminate in which multiple external electrode patterns 13a to 13e and coil conductor patterns 12a to 12c are arranged in a matrix is formed, and the mother laminate is cut into individual laminates by dicing. At this time, as Figure 1 shown, the external electrode patterns 13a to 13e are exposed from the surfaces of the laminate corresponding to the mounting surface 11a, the first end surface 11b, and the second end surface 11c. In addition, in this case, the external electrode patterns 13a to 13e and the opening 17 may not be in an L shape, but may be formed in a T shape or a cross shape and become an L shape through the above-mentioned dicing.

[0074] Next, the laminate is fired under specified conditions to sinter the insulating paste layer, the coil conductor pattern, and the external electrode pattern, forming an insulator layer, a coil conductor layer, and an external electrode layer. After that, barrel processing is performed to form Figure 1 the base body 11, the coil 12, and the external electrodes 13x, 13y shown. After that, Ni plating and Sn plating with a thickness of 2 μm to 10 μm are sequentially applied to the external electrodes 13x, 13y, thereby completing the laminated inductor component 10.

[0075] In the above, the insulating paste that is the material for the outer layer insulating paste layers 15a, 15b, the insulating paste layers 16a to 16d, and the marking insulating paste layer 18 is, for example, a glass paste in which glass powder is contained in varnish. In addition, the insulating paste that is the material for the outer layer insulating paste layers 15a, 15b, and the marking insulating paste layer 18 can be photosensitive or non-photosensitive. In addition, the insulating paste that is the material for the marking insulating paste layer 18 can contain pigments, whereby each surface of the laminated inductor component 10 can be identified.

[0076] In addition, the photosensitive conductive paste forming the coil conductor patterns 12a to 12c and the external electrode patterns 13a to 13e is, for example, a paste in which metal powders such as Ag, Cu, Au, and glass powder are contained in varnish. Bi, Li, Na, K, Mg, Ca, Sr, Ba, Co, Zn, B, Pb, Al, Zr, P, V, etc. may be added to the glass powder contained in the insulating paste and the conductive paste.

[0077] Next, the structure of the coil conductor layers 12a to 12c sintered by firing a conductive paste containing such metal powders and glass powder through a firing process will be described.

[0078] Figure 3 (a) to Figure 3 (d) show the structure of the coil conductor layers 12a to 12c sintered at each firing temperature t1 to t3 and firing times T1, T2 in a cross-section (transverse section) orthogonal to the extending direction of the coil conductor layers 12a to 12c.

[0079] The firing temperatures t1 to t3 are t1 < t2 < t3, and the firing times T1, T2 are T1 < T2. That is, the degree of sintering progress of the coil conductor layers 12a to 12c at the completion of the firing process progresses from Figure 3 (a) to Figure 3 (b), from Figure 3 (b) to Figure 3 (c), and from Figure 3 (b) to Fig. (d).

[0080] As shown in Figure 3 (a) to Figure 3 (d), the coil conductor layers 12a to 12c include a metal part M sintered from the metal powders contained in the conductive paste and a glass part GLA sintered from the glass powder. In addition, the glass part GLA includes an internal glass GLAi contained in the metal part M and an exposed glass GLAo exposed from the metal part M.

[0081] In addition, the substrate 11 includes a peripheral glass GLB as the glass of the substrate 11 within 10 μm around the coil conductor layers 12a to 12c. It can be seen that in Figure 3 (a) and Figure 3 (b) where the sintering is relatively not carried out, the glass part GLA not only includes the internal glass GLAi but also the exposed glass GLAo. On the other hand, in Figure 3 (c) and Figure 3 (d) where the sintering progresses, the glass part GLA does not include the exposed glass GLAo and only includes the internal glass GLAi. In addition, it can be seen that the outer periphery of the metal part M is smoothed in proportion to the progress of sintering.

[0082] Using Figure 5The schematic diagram shown illustrates the details of the sintering process of the coil conductor layers 12a to 12c. As Figure 5 (a) shows, before firing, the coil conductor patterns 12a to 12c are in a state where metal powder M and glass powder GLA are dispersed in a varnish 19 which is a photosensitive conductive paste after photocuring and serves as an adhesive.

[0083] If firing starts in this state, then as Figure 5 (b) shows, the varnish 19 burns and scatters, and the metal powder M sinters into the metal part M, and local contraction (necking) occurs, increasing the interface of adjacent metal parts M. At this time, the glass powder GLA also sinters into the glass part GLA, however, the part with a relatively low softening point in the glass part GLA softens and starts to flow at the interface of the metal part M.

[0084] Next, as Figure 5 (c) shows, the sintering of the metal part M is further promoted by the softened glass part GLA flowing at the interface of the metal part M, and the particle size of the metal part M increases. Additionally, at this time, as the glass part GLA, an inclusion glass GLAi which has a relatively high softening point and a small flow amount and is included and sintered in the metal part M, and an exposed glass GLAo which has a relatively low softening point and flows and is sintered at the outer periphery of the metal part M are formed. Furthermore, the softening and flowing of the glass part GLA progresses faster than that of the exposed glass GLAo, and the part that is extruded to the periphery of the metal part M and sintered becomes the peripheral glass GLB of the base 11. Therefore, at this stage, a coil conductor layer 12a to 12c as shown in Figure 3 (a), Figure 3 (b) is formed, which includes the metal part M and the glass part GLA, and the glass part GLA includes the inclusion glass GLAi and the exposed glass GLAo. At this time, since the coil conductor layers 12a to 12c are formed in a state where they are surrounded by a partially softened peripheral glass GLB, the smoothing of the outer periphery of the coil conductor layers 12a to 12c composed of the metal part M and the exposed glass GLAo is promoted.

[0085] Then, as Figure 5 (d) shows, if firing further proceeds, the particle size of the metal part M further increases, and the exposed glass GLAo is extruded to the periphery of the metal part M to become the peripheral glass GLB. Thus, at this stage, a coil conductor layer 12a to 12c as shown in Figure 3 (c), Figure 3 (d) is formed, which includes the metal part M and the glass part GLA, and the glass part GLA only includes the inclusion glass GLAi. At this time, since the coil conductor layers 12a to 12c are formed in a state where the exposed glass GLAo is also extruded to the periphery of the metal part M, the outer periphery of the metal part M of the coil conductor layers 12a to 12c is smoothed.

[0086] As described above, the proportion of the glass GLAi contained in the glass part GLA can be controlled by the extrusion amount of the exposed glass GLAo (peripheral glass GLB formation), that is, the progress of sintering.

[0087] Figure 4 (a) to Figure 4 (d) show the structures of the coil conductor layers 12a to 12c sintered at each firing temperature t1 to t3 and each firing time T1, T2 when Bi is added to the glass powder of the conductive paste for forming the coil conductor layers 12a to 12c. By adding Bi, the softening temperature (softening point) of the glass part sintered from the glass powder is lower than that of the glass part sintered from the glass powder without adding Bi.

[0088] As a result, it can be known that when compared at the same firing temperature and firing time, Figure 3 compared with the coil conductor layers 12a to 12c of Figure 3 , the progress of sintering is faster, the proportion of the glass GLAi contained in the glass part GLA is larger, and the smoothing of the outer periphery of the coil conductor layers 12a to 12c is promoted. Thus, the proportion of the glass contained in the glass part GLA can also be adjusted according to the presence or absence of Bi added to the glass powder. In addition, the degree of decrease in the softening point of the glass part sintered from the glass powder added with Bi is substantially proportional to the addition amount of Bi. Therefore, the above-mentioned proportion of the contained glass can also be adjusted according to the addition amount of Bi added to the glass powder.

[0089] In addition, from the above description, it can be seen that the softening point of the part of the glass powder contained in the coil conductor patterns 12a to 12c that does not become the contained glass GLAi but becomes the exposed glass GLAo and the peripheral glass GLB is relatively low and the fluidity is relatively high. Therefore, in the coil conductor layers 12a to 12c, the softening point of the exposed glass GLAo and the softening point of the peripheral glass GLB are below the softening point of the contained glass GLAi. In addition, the softening point of the peripheral glass GLB is below the softening point of the exposed glass GLAo. That is, for the softening point, the peripheral glass GLB ≤ the exposed glass GLAo ≤ the contained glass GLAi. In addition, if the glass of the base 11 further outside than the peripheral glass such as the central part and the outer edge part of the base 11 is set as the peripheral glass, it is preferable that the softening point of the peripheral glass GLB is lower than the softening point of the peripheral glass. In this case, since the coil conductor layers 12a to 12c are formed in a state surrounded by the relatively easily softened peripheral glass GLB, the smoothing of the outer periphery of the coil conductor layers 12a to 12c is promoted, and since there is the relatively difficult-to-soften peripheral glass, the strength and shape stability of the base 11 are improved.

[0090] In addition, the filling element added to the glass powder to lower the softening point of the glass part is not limited to Bi, and can be any one of Bi, Li, Na, K, Mg, Ca, Sr, Ba, Co, Zn, B, Pb, Al, Zr, P, and V. That is, it is preferable that the peripheral glass GLB contains one or more of the above filling elements. At this time, it is preferable that the concentration of the filling element (the total value of the concentrations of the above filling elements) is higher in the peripheral glass GLB than in the outer glass. In addition, from the viewpoint of the softening point during the sintering process, when the glass powder contained in the conductor paste forming the coil conductor patterns 12a to 12c contains one or more of the above filling elements, for the concentration of the filling element, the peripheral glass GLB ≥ the exposed glass GLAo ≥ the internally contained glass GLAi.

[0091] In addition, as Figure 6 shown, if in the region exceeding 10 μm around the coil conductor layers 12a to 12c, that is, in the outer glass, the softening point decreases, there may be a short circuit between the adjacent coil conductor layers 12a to 12c due to the excessive flow of the metal part M. Therefore, it is preferable that the above filling element is not contained in the outer glass or the concentration of the filling element is lower than that of the peripheral glass GLB.

[0092] In addition, since the higher the concentration of the filling element in the glass, the lower the concentration of Si in the glass, for the concentration of Si, the peripheral glass GLB < the outer glass.

[0093] In addition, in the laminated inductor component 10, it is preferable that the metal part M contained in the coil conductor layers 12a to 12c forms a plurality of crystals, and the average particle diameter of the crystals is 0.5 μm or more and 15.0 μm or less. Since the grain boundaries that inhibit current flow are reduced when the average particle diameter of the above crystals is 0.5 μm or more, low resistance of the coil 12 can be achieved. In addition, when the average particle diameter of the above crystals is 15.0 μm or less, excessive enlargement of the crystals can be suppressed and the smoothing of the outer periphery of the coil conductor layers 12a to 12c can be promoted.

[0094] The average particle diameter of the crystals can be analyzed by OIM (Orientation Imaging Microscopy), which is an image analysis device. In addition, when it cannot be measured by OIM, FIB (Focused ion beam) and SIM (Scanning ion Microscopy) can also be used for analysis.

[0095] In addition, in the latter case, as Figure 7As shown, specifically in the cross-sectional images of the coil conductor layers 12a to 12c, the area of the crystal 20 of the metal part M is calculated, and the diameter d of a perfect circle with the same area as this area is calculated. Based on this as the particle size, the average particle size is calculated. When calculating the average particle size, for example, five cross-sectional images of the coil conductor layers 12a to 12c can be obtained from the cross-section passing through the central part of the substrate 11, and the arithmetic mean of the particle sizes of the crystals 20 in this image can be calculated.

[0096] In addition, as a method for measuring the softening point, a part containing each glass is cut out as a sample from the substrate 11 or the coil conductor layers 12a to 12c, and it is only necessary to confirm the molten state using a high-temperature microscope. Specifically, the sample is observed using a high-temperature microscope in a vacuum and heated using near-infrared rays or the like, and the softening state of the sample is confirmed. The point at which softening starts is set as the softening point.

[0097] In addition, Figure 8 is a diagram showing the state after the firing process in an embodiment of the multilayer inductor component 10. In Figure 8 , the concentration of the filling element contained in the glass is represented by shading. Except for the part of the coil conductor layer, the lighter part is the area where the concentration of the filling element is higher, and the darker area is the area where the concentration of the filling element is lower. In the above embodiment, an insulating paste containing glass powder and a conductive paste containing metal powder and glass powder are used to form a laminate in which coil conductor patterns formed of the conductive paste are arranged between a plurality of insulating paste layers formed of the insulating paste. In addition, in the above embodiment, the laminate is fired through a firing process, and the above metal powder and the above glass powder are sintered into a metal part and a glass part, respectively. Further, in the above embodiment, the glass powder contained in the above conductive paste uses a material with a lower softening point than the glass powder contained in the above insulating paste.

[0098] As Figure 8 shown, it can be seen that in the process of firing the above laminate, an internally contained glass GLAi ( Figure 8 the part of A) formed by sintering the glass powder contained in the above conductive paste and contained in the metal part, a peripheral glass GLB ( Figure 8 the part of B) formed by extruding the glass powder contained in the above conductive paste to the periphery of the metal part and sintering it, and an outer peripheral glass formed by sintering the glass powder contained in the above insulating paste ( Figure 8 the part of C) are formed. In addition, it can be seen that for the concentration of the filling element, the peripheral glass GLB > the outer peripheral glass.

[0099] In addition, if the direction orthogonal to the plane in which the coil conductor layers 12a to 12c extend on the substrate 11 ( Figure 9If the outermost glass in the vertical direction of the paper surface (of [the layer stack type inductor component 10]) is set as the outer layer glass, then in the layer stack type inductor component 10, the glass contained in the insulator layer 18 (marking layer) becomes the outer layer glass. Here, the concentration of Si in the peripheral glass is lower than the concentration of Si in the outer layer glass, that is, when the concentration of the aforementioned filling element in the outer layer glass is lower than the concentration of the filling element in the peripheral glass, the clarity of the insulator layer 18 located on the outermost side of the substrate 11 is improved. At this time, as Figure 10 shown, if the alignment mark 21 used when singling the mother laminate into the insulator layer 18 is formed, then due to the improvement in the clarity of the insulator layer 18, the visibility of the alignment mark 21 is improved and the singling accuracy is improved.

[0100] On the other hand, when the concentration of Si in the peripheral glass is higher than the concentration of Si in the outer layer glass, a filler for improving mechanical strength can be added to the outer layer glass, and the strength of the substrate 11 is improved.

[0101] In the layer stack type inductor component configured as described above, the following effects can be obtained.

[0102] (1) The coil conductor layers 12a to 12c include a metal part M and a glass part GLA, and the glass part GLA includes an embedded glass GLAi contained in the metal part M. In this structure, due to the embedded glass GLAi, the surface area of the coil conductor layers 12a to 12c is increased. That is, the coil 12 can be made to have a low resistance without using voids, and the aforementioned various problems will not occur.

[0103] In addition, for example, in the layer stack type inductor component 10, in order to improve the acquisition efficiency of inductance, when the inner diameters of the coil conductor layers 12a to 12c are enlarged and the outer peripheries of the coil conductor layers 12a to 12c approach the outer periphery of the substrate 11, there are no voids in the coil conductor layers 12a to 12c either, so a reduction in the strength of the substrate 11 can be suppressed.

[0104] (2) Preferably, in a cross-section orthogonal to the extending direction of the coil conductor layers 12a to 12c, a cross-section in which the proportion of the above-mentioned embedded glass in the glass part GLA is less than 50% by area is included. In this structure, since the surface area of the coil conductor layers 12a to 12c is also increased by exposing the glass GLAo, further low-resistance of the coil 12 can be achieved.

[0105] (3) Preferably, in a cross-section orthogonal to the extending direction of the coil conductor layers 12a to 12c, the cross-section includes the glass portion GLA in which the proportion of the glass contained therein is 50% or more by area ratio. In this structure, the surface area of the coil conductor layers 12a to 12c is increased, and the smoothing of the outer periphery of the metal portion M of the coil conductor layers 12a to 12c is promoted. Therefore, the generation of eddy currents caused by the unevenness in the generation direction of the magnetic flux in the central portion of the coil 12 can be suppressed, and the loss at high frequencies can be reduced. In addition, the reduction in the mechanical strength of the coil 12 can be prevented.

[0106] (4) Preferably, in a cross-section orthogonal to the extending direction of the coil conductor layers 12a to 12c, the cross-section includes the glass portion GLA in which the proportion of the glass GLAi contained therein is 100% by area ratio. In this structure, the smoothing of the outer periphery of the metal portion M of the coil conductor layers 12a to 12c can be further promoted.

[0107] (5) Preferably, in a cross-section orthogonal to the extending direction of the coil conductor layers 12a to 12c, the cross-section includes the cross-section in which the proportion of the contained glass GLAi relative to the coil conductor layers 12a to 12c is 1.0% or more and 20.0% or less by area ratio. In this structure, since the proportion of the above-mentioned contained glass GLAi is 20.0% or less, the smooth flow of current in the coil conductor layers 12a to 12c is promoted. In addition, since the proportion of the above-mentioned contained glass GLAi is 1.0% or more, the surface area of the coil conductor layers 12a to 12c can be increased. Furthermore, the above-mentioned area ratio is preferably achieved by the central cross-section of the longest straight portion of the coil conductor layers 12a to 12c, and is preferably achieved by the cross-section of the outermost coil conductor layer 12a or the coil conductor layer 12b. In these structures, the effects of the above-mentioned area ratio are most significant.

[0108] (6) Preferably, the softening point of the peripheral glass GLB is lower than the softening point of the outer peripheral glass. In this structure, since the coil conductor layers 12a to 12c are formed in a state of being surrounded by the relatively easily softened peripheral glass GLB, the smoothing of the outer periphery of the coil conductor layers 12a to 12c is promoted.

[0109] (7) Preferably, the softening point of the peripheral glass GLB is equal to or lower than the softening point of the contained glass GLAi. In this structure, since the coil conductor layers 12a to 12c are formed in a state of being surrounded by the relatively easily softened peripheral glass GLB, the smoothing of the outer periphery of the coil conductor layers 12a to 12c is promoted.

[0110] (8) Preferably, the peripheral glass GLB contains more than one filling element, and the concentration of the filling element in the peripheral glass GLB is higher than that in the outer peripheral glass. In this structure, since the coil conductor layers 12a to 12c are formed in a state of being surrounded by the peripheral glass GLB that is relatively easily softened, the smoothing of the outer peripheries of the coil conductor layers 12a to 12c is promoted.

[0111] (9) Preferably, the concentration of Si in the peripheral glass GLB is lower than the concentration of Si in the outer peripheral glass. In this structure, since the coil conductor layers 12a to 12c are formed in a state of being surrounded by the peripheral glass GLB that is relatively easily softened, the smoothing of the outer peripheries of the coil conductor layers 12a to 12c is promoted.

[0112] (10) Preferably, the concentration of Si in the peripheral glass GLB is lower than the concentration of Si in the outer layer glass contained in the outermost insulator layer 18. In this structure, since the clarity of the outermost part of the substrate 11 is improved and the visibility of the alignment mark 21 is improved, the singulation accuracy is improved.

[0113] (11) It is also possible to make the concentration of Si in the peripheral glass GLB higher than the concentration of Si in the outer layer glass. In this structure, the strength of the substrate 11 is increased.

[0114] (12) Preferably, the average grain diameter of the crystals of the metal part M contained in the coil conductor layers 12a to 12c is 0.5 μm or more and 15.0 μm or less. In this structure, since the grain boundaries that inhibit the flow of electrons are reduced, the low resistance of the coil conductor layers 12a to 12c can be achieved, and the excessive enlargement of the crystals is suppressed and the smoothing of the outer peripheries of the coil conductor layers 12a to 12c is promoted.

[0115] (13) Preferably, the substrate 11 is a sintered body. In this structure, the strength of the substrate 11 is increased.

[0116] (14) Preferably, the outer surface of the substrate 11 includes a mounting surface 11a on which both the first external electrode 13x and the second external electrode 13y are arranged, a first end surface 11b on which only the first external electrode 13x is arranged, and a second end surface 11c on which only the second external electrode 13y is arranged. In this structure, when mounting the stacked inductor component 10 on a substrate, the mounting solder forms solder feet at the first end surface 11b and the second end surface 11c, and the fixing force toward the substrate of the stacked inductor component 10 can be increased. In addition, in this case, it is preferable that the mounting surface 11a, the first end surface 11b, and the second end surface 11c are orthogonal to the plane (main surface of the insulator layer) in which the coil conductor layers 12a to 12c extend.

[0117] In this structure, the magnetic flux generated by the coil 12 is difficult to be cut off by the first external electrode 13x and the second external electrode 13y, and it is possible to suppress the decrease in the Q value caused by eddy current loss.

[0118] (15) Preferably, the softening point of the peripheral glass GLB is below the softening point of the glass portion GLA (including the internal glass GLAi and the exposed glass GLAo). With this structure, since the coil conductor layers 12a to 12c are formed in a state of being surrounded by the relatively easily softened peripheral glass GLB, the smoothing of the outer peripheries of the coil conductor layers 12a to 12c is promoted.

[0119] (16) The laminated inductor component 10 is preferably manufactured by a manufacturing method having: a step of forming a laminate in which coil conductor patterns 12a to 12c made of a conductive paste are arranged between a plurality of insulating paste layers made of an insulating paste, using the insulating paste containing glass powder and the conductive paste containing metal powder and glass powder; and a step of firing the laminate to sinter the metal powder and the glass powder into the metal portion M and the glass portion GLA, respectively. The glass powder contained in the conductive paste uses a material having a lower softening point than the glass powder contained in the insulating paste. In the step of firing the laminate, the internal glass GLAi formed by including the glass powder contained in the conductive paste in the metal portion M and sintering it, and the peripheral glass GLB formed by extruding the glass powder contained in the conductive paste to the periphery of the metal portion M and sintering it are formed. In this method, due to the internal glass GLAi and the peripheral glass GLB formed in the step of firing the laminate, the surface area of the coil conductor layers 12a to 12c sintered from the coil conductor patterns 12a to 12c increases, and the smoothing of the outer peripheries is promoted.

[0120] In addition, the above-described embodiments can be modified as follows.

[0121] · The metal portion M of the coil conductor layers 12a to 12c may also be formed of a good conductor other than Ag, such as Cu or Au. In addition, the insulator layers 15a, 15b, 16a to 16c, and 18 may not be glass, but may have a structure including ferrite, resin, etc. That is, the base 11 may also be a sintered body other than glass or a structure other than the sintered body. In addition, if the base 11 is a sintered body, the strength of the base 11 is increased. In addition, the electroplating applied to the external electrode is not particularly limited, and may be a single body or an alloy of Sn, Ni, Ag, Cu, Pd, Au, and further a multilayer structure formed by combining a plurality of them.

[0122] · The insulator layer 16, the opening 17 of the insulator layer 16, and the via hole 14 may also be formed by a manufacturing method other than photolithography, such as crimping of an insulating material sheet, spin coating, or laser processing or drilling after applying an insulating paste.

[0123] · Preferably, the ratio of the width w to the thickness t of the cross-section of the coil conductor layers 12a to 12c, i.e., the aspect ratio t / w, is high. Due to the skin effect, high-frequency current mainly passes through the inner side surfaces of the winding shapes of the coil conductor layers 12a to 12c. Therefore, if the thickness t is large, the resistance to high-frequency current can be reduced. Additionally, if the width w is small, the inner diameter portion of the winding shapes of the coil conductor layers 12a to 12c can be relatively widened, and the acquisition efficiency of inductance can be improved.

[0124] · The shape of the external electrode is not particularly limited. It can be a shape formed on the first end face and its adjacent four faces, and the second end face and its adjacent four faces, or it can be a shape formed only on the mounting surface.

[0125] · The relationship between the stacking direction and the mounting surface is not particularly limited either. It can also be a structure in which the stacking direction is orthogonal to the mounting surface.

[0126] · The external dimensions are not particularly limited. For example, based on the long side dimension and the short side dimension in the mounting surface, they can be sizes such as 1005, 0804, 0603, 0402, etc., or other ratios. Additionally, the height dimension is arbitrary and can be the same as the long side dimension and the short side dimension, or a dimension different from them.

[0127] Description of Reference Numerals

[0128] 11... Substrate, 12... Coil, 13... External Electrode, 14... Via Hole, 15a, 15b... Insulator Layer / Insulating Paste Layer for Outer Layer, 16a to 16d... Insulator Layer / Insulating Paste Layer, 20... Crystal, GLAi... Glass Inside, GLAo... Exposed Glass, GLB... Peripheral Glass.

Claims

1. A stacked inductor component, comprising: A substrate, which is an insulator and includes a plurality of insulator layers; and A coil having a plurality of coil conductor layers, wherein, The plurality of coil conductor layers are formed in the substrate with the insulator layers of the substrate interposed therebetween, and the plurality of coil conductor layers are electrically connected to each other via via holes in the substrate. The substrate contains glass. If the glass of the substrate within 10 μm around the coil conductor layer is defined as peripheral glass and the glass of the substrate further outside than the peripheral glass is defined as outer peripheral glass, the softening point of the peripheral glass is lower than the softening point of the outer peripheral glass.

2. A stacked inductor component, comprising: A substrate, which is an insulator and includes a plurality of insulator layers; and Coil, having a plurality of coil conductor layers, wherein, The plurality of coil conductor layers are formed in the substrate with the insulator layers of the substrate interposed therebetween, and the plurality of coil conductor layers are electrically connected to each other via via holes in the substrate. The substrate contains glass. If the glass of the substrate within 10 μm around the coil conductor layer is defined as peripheral glass and the glass of the substrate further outside than the peripheral glass is defined as outer peripheral glass, the peripheral glass contains one or more elements among Bi, Li, Na, K, Mg, Ca, Sr, Ba, Co, Zn, B, Pb, Al, Zr, P, V, and with respect to the concentration of at least any one of the above elements, the peripheral glass has a higher concentration than the outer peripheral glass.

3. The stacked inductor component according to claim 2, wherein The concentration of Si in the peripheral glass is lower than the concentration of Si in the outer peripheral glass.

4. The stacked inductor component according to claim 2, wherein If the glass on the outermost side in the direction orthogonal to the plane in which the coil conductor layer extends in the substrate is defined as outer layer glass, the concentration of Si in the peripheral glass is higher than the concentration of Si in the outer layer glass.

5. The stacked inductor component according to claim 4, wherein The outer layer glass contains pigments. Fillers for improving mechanical strength are added to the outer layer glass.

6. The stacked inductor component according to claim 2, wherein The metal parts included in the plurality of coil conductor layers form a plurality of crystals, and the average particle diameter of the plurality of crystals is 0.5 μm or more and 15.0 μm or less.

7. The stacked inductor component according to claim 2, wherein The substrate is a sintered body.

8. The stacked inductor component according to claim 2, wherein A first external electrode and a second external electrode are further provided. The first external electrode and the second external electrode are arranged along the outer surface of the substrate and are electrically connected to the first end and the second end of the coil respectively. The outer surface includes a mounting surface on which both the first external electrode and the second external electrode are arranged, a first end surface on which only the first external electrode among the first external electrode and the second external electrode is arranged, and a second end surface on which only the second external electrode among the first external electrode and the second external electrode is arranged. The mounting surface, the first end surface, and the second end surface are parallel to the direction in which the coil conductor layers are arranged.

9. The stacked inductor component according to claim 8, wherein, the mounting surface is parallel to the winding axis of the coil, the first external electrode is formed in an L shape from the mounting surface toward the first end face, the second external electrode is formed in an L shape from the mounting surface toward the second end face, the first external electrode and the second external electrode are coated, the coating is a multi-layer structure, the coating is applied with a Ni coating and a Sn coating in sequence starting from the first external electrode and the second external electrode sides, the long side dimension and the short side dimension of the mounting surface are one of the following: 1005, 0804, 0603, 0402, the height dimension of the substrate is the same as or different from the long side dimension or the short side dimension of the mounting surface.

10. The stacked inductor component according to claim 8, wherein, the long side dimension and the short side dimension of the mounting surface are one of the following: 1005, 0804, 0603, 0402.

11. The stacked inductor component according to claim 2, wherein, regarding the total value of the concentration of the above elements, the peripheral glass is higher than the outer peripheral glass.

12. The stacked inductor component according to claim 2, wherein, the coil conductor layer contains a metal element and a glass part.

13. The stacked inductor component according to claim 12, wherein the coil conductor layer contains an inclusion glass, and the inclusion glass is a glass included in the metal element, in a cross-section orthogonal to the extending direction of the coil conductor layer, the proportion of the inclusion glass in the glass part is a cross-section with an area ratio of less than 50%.

14. The stacked inductor component according to claim 12, wherein, the coil conductor layer contains an inclusion glass, and the inclusion glass is a glass included in the metal element, in a cross-section orthogonal to the extending direction of the coil conductor layer, the proportion of the inclusion glass in the glass part is a cross-section with an area ratio of 50% or more.

15. The stacked inductor component according to claim 12, wherein, the coil conductor layer contains an inclusion glass, and the inclusion glass is a glass included in the metal element, in a cross-section orthogonal to the extending direction of the coil conductor layer, the proportion of the inclusion glass in the glass part is a cross-section with an area ratio of 100%.

16. The stacked inductor component according to claim 12, wherein, the coil conductor layer contains an inclusion glass, and the inclusion glass is a glass included in the metal element, in a cross-section orthogonal to the extending direction of the coil conductor layer, the proportion of the inclusion glass in the coil conductor layer is a cross-section with an area ratio of 1.0% or more and 20.0% or less.

17. The stacked inductor component according to claim 16, wherein, the cross-section is the central cross-section of the longest straight part of the coil conductor layer, the coil conductor layer having the cross-section is the outermost coil conductor layer.

18. The stacked inductor component according to claim 2, wherein, the coil conductor layers are respectively in a shape that wraps less than one turn, The above coil conductor layer contains Ag, Cu, or Au, At least a part of the above coil conductor layer is surrounded by the peripheral glass.

Images