JP2009117665A - Laminated inductor and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated inductor capable of making compatible both the suppression of the occurrence of inter-layer separation and reduction in connection failure, and to provide a manufacturing method of the laminated inductor. <P>SOLUTION: The laminated inductor 10 includes: a laminate 12; and a coil arranged in the laminate 12 and formed by electrically connecting a plurality of strip-shaped conductor patterns. The conductor patterns have a pair of broad faces S1, S2, intersecting the lamination direction and mutually opposing. The laminate 12 is arranged at the edge of the conductor pattern at the side of the broad face S1. Therefore, the conductor patterns have an overlapping part 20a overlapping with the laminate 12 at the edge and the other non-overlapping sections 20b when viewed from the lamination direction. A gap V is formed between one portion of a region in the non-overlapping section 20b in the broad face S1 and the laminate 12. The conductor patterns are connected to a through-hole conductor via a connection conductor provided on the broad face S1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a multilayer inductor and a method for manufacturing the same.

Conventionally, a step of preparing a magnetic green sheet, a step of forming a conductor pattern on the magnetic green sheet, and an auxiliary magnetic material surrounding the conductor pattern on the magnetic green sheet and thicker than the thickness of the conductor pattern A method for manufacturing a multilayer inductor including a step of forming a layer is known (see, for example, Patent Document 1).
Japanese Patent Publication No. 7-123091

  In recent years, for example, a multilayer inductor used as a choke coil for a power source of a mobile phone has a good direct current superposition characteristic with little decrease in inductance value even when a large direct current (for example, about 1 A to 5 A) is passed. (A DC resistance value is small).

  As a technique for reducing the DC resistance value of the multilayer inductor, it is conceivable to increase the width of the conductor pattern constituting the coil disposed inside the multilayer inductor. However, in this case, if the outer diameter of the coil is not changed, the inductance value becomes small. Therefore, in general, increasing the thickness of the conductor pattern is performed.

  At this time, when a multilayer inductor having a large conductor pattern thickness is manufactured by a general sheet lamination method as a multilayer inductor manufacturing method, a conductor paste is applied in a predetermined pattern on a green sheet and dried. Thus, when multiple sheets of green sheets with conductive coatings formed on them are stacked, the thickness of the conductive coatings is increased, so the entire green sheet stack with green sheets stacked is uniform. Can not be crimped to. For this reason, in the manufactured multilayer inductor, variations in electrical characteristics or delamination may occur.

  Therefore, in order to solve this problem, in the conventional method of manufacturing a multilayer inductor as described in Patent Document 1, an auxiliary material that surrounds the periphery of the conductor pattern and is thicker than the thickness of the conductor pattern on the magnetic green sheet. A magnetic material layer is formed. However, in the multilayer inductor manufactured as described above, one of the wide surfaces of the strip-shaped conductor pattern is separated from the multilayer body. For this reason, conductor patterns adjacent in the stacking direction are not electrically connected by the through-hole conductor, and connection failure may occur.

  On the other hand, it is also conceivable to form an auxiliary magnetic material layer that surrounds the periphery of the conductor pattern and is thinner than the thickness of the conductor pattern on the magnetic green sheet (see, for example, Japanese Patent No. 3582454). However, in this case, the entire green sheet laminate in which the green sheets are laminated cannot be uniformly crimped, and there is a problem that delamination occurs in the manufactured multilayer inductor.

  An object of the present invention is to provide a multilayer inductor capable of achieving both suppression of delamination and reduction of connection failure, and a method for manufacturing the same.

  A multilayer inductor according to the present invention includes a multilayer body formed by laminating a plurality of insulator layers, first and second external electrodes respectively disposed on the outer surface of the multilayer body, and a plurality of strip-shaped conductors The coil is configured to be electrically connected to each other, and is arranged inside the laminated body, and the first lead that is electrically connected to one end of the coil and electrically connected to the first outer conductor. A conductor and a second lead conductor that is electrically connected to the other end of the coil and electrically connected to the second external electrode, and the conductor patterns are arranged to face each other in the stacking direction of the stacked body. The first and second wide surfaces are provided, and a part of the multilayer body is disposed at the edge of the conductor pattern on the first wide surface side, and a part of the multilayer body is disposed at the edge. When the conductor pattern is viewed from the stacking direction, An overlapping portion in which the conductor pattern is overlapped with a portion arranged at the edge of the body, and a non-overlapping portion that is a portion other than the overlapping portion, and the region of the non-overlapping portion of the first wide surface A gap is formed between a part and the laminate, and the conductor pattern has an end connected to a through-hole conductor extending in the lamination direction. The conductor pattern and the through-hole conductor The connection conductor is connected via a connection conductor provided only at the end, and the connection conductor is larger than the through-hole conductor when viewed from the stacking direction, and is a region in a non-overlapping portion of the first wide surface. It is arranged inside.

  In the multilayer inductor according to the present invention, a part of the multilayer body is arranged at the edge of the conductor pattern on the first wide surface side. Such a configuration is brought about by forming a ceramic coating film so as to cover the edge of the conductive coating film when the multilayer inductor according to the present invention is manufactured. Therefore, compared to the conventional manufacturing method in which the auxiliary magnetic material layer is formed so as to surround the conductor pattern, when a plurality of green sheets are laminated, the ceramic coating film formed on one green sheet And an area where the one green sheet and another adjacent green sheet are in contact with each other, and the ceramic coating formed on the one green sheet by the edge of the conductive coating and the one green sheet Combined with the fact that other adjacent green sheets are more strongly pressed, delamination is less likely to occur in the manufactured multilayer inductor. In the multilayer inductor according to the present invention, the conductor pattern is connected to the first through-hole conductor via the connection conductor provided on the first wide surface, and the connection conductor is viewed from the lamination direction. In addition, it is larger than the through-hole conductor, and is disposed in a region in the non-overlapping portion of the first wide surface. For this reason, the connection pattern reliably connects the conductor pattern and the through-hole conductor, and the connection reliability is greatly improved. Therefore, it is possible to achieve both suppression of delamination and reduction of connection failure.

  On the other hand, the multilayer inductor manufacturing method according to the present invention includes a green sheet preparing step of preparing a green sheet, a through hole forming step of forming a through hole penetrating in the thickness direction in the green sheet, and a conductive paste through hole. A conductive coating film forming step for forming a belt-shaped conductive coating film by applying a conductive paste in a predetermined pattern on the green sheet and drying, and covering the edge of the conductive coating film and the conductive coating film The ceramic coating film that forms a ceramic coating film whose height from the green sheet is higher than the height of the conductive coating film from the green sheet by applying and drying the ceramic slurry so as to expose the upper surface other than the edge of By forming a conductive paste on the exposed surface of the conductive coating film and drying the conductive paste only on the edge of the conductive coating film, Height from over bets is characterized in that it comprises a connecting conductive coating film forming step of forming a high connection conductive coating than the height of the ceramic coating of the green sheet.

  In the method for manufacturing a multilayer inductor according to the present invention, the ceramic coating film is formed so as to cover the edge of the conductive coating film and to expose the upper surface other than the edge of the conductive coating film. Is higher than the height of the conductive coating film from the green sheet. Therefore, compared to the conventional manufacturing method in which the auxiliary magnetic material layer is formed so as to surround the conductor pattern, when a plurality of green sheets are laminated, the ceramic coating film formed on one green sheet And an area where the one green sheet and another adjacent green sheet are in contact with each other, and the ceramic coating formed on the one green sheet by the edge of the conductive coating and the one green sheet Combined with the fact that other adjacent green sheets are more strongly pressed, delamination is less likely to occur in the manufactured multilayer inductor. In the multilayer inductor manufacturing method according to the present invention, a conductive conductive coating film for connection is formed on the exposed surface of the conductive coating film so that the height from the green sheet is higher than the height of the ceramic coating film from the green sheet. ing. Therefore, when a plurality of green sheets are stacked, the conductive conductive film for connection formed on the exposed surface of the conductive film in one green sheet is crushed by another green sheet adjacent to the one green sheet. The conductive coating film for connection securely connects the conductive coating film on one green sheet to the portion filled in the through hole formed on the other green sheet in the conductive coating film on the other green sheet. Connection reliability is greatly improved. Therefore, it is possible to achieve both suppression of delamination and reduction of connection failure.

  Preferably, the shrinkage ratio during firing of the conductive conductive coating film is smaller than the shrinkage ratio during firing of the conductive paint film. In this way, since the conductive film for connection is less likely to shrink during firing, the conductive film on one green sheet and the other green sheet among the conductive films on the other green sheet even after firing. The connection with the portion filled in the formed through hole can be reliably maintained. As a result, connection failures can be further reduced.

  The multilayer inductor manufacturing method according to the present invention includes a green sheet preparing step of preparing a green sheet, a through hole forming step of forming a through hole penetrating in the thickness direction in the green sheet, and a conductive paste through hole. A first conductive coating film forming step for forming a strip-shaped first conductive coating film by applying a conductive paste in a predetermined pattern on the green sheet and then drying the conductive paste; The ceramic sheet is applied so as to cover the edge of the first conductive film and the upper surface other than the edge of the first conductive coating film is exposed and dried, so that the height from the green sheet is the green sheet of the first conductive coating film. A first ceramic coating film forming step for forming a first ceramic coating film that is higher than the height of the film and a band-shaped nth conductive film (where n is an integer of 2 or more) The nth conductive coating film forming step, the nth ceramic coating film forming step for forming the nth ceramic coating film, and the connecting conductive coating film forming step, The conductive paste is applied in a predetermined pattern on the exposed surface of the mth conductive film (where m is an integer satisfying m = n-1) and the mth ceramic coating, and then dried. The band-shaped nth conductive coating film is overlapped with the mth conductive coating film when viewed from the direction and the height from the green sheet is higher than the height of the mth ceramic coating film from the green sheet. In the nth ceramic coating film forming step, the ceramic slurry is applied and dried so as to cover the edge portion of the nth conductive coating film and expose the upper surface other than the edge portion of the nth conductive coating film. The height from the green sheet is the nth conductive coating The nth ceramic coating film is formed so as to be higher than the height of the green sheet, and in the conductive coating film forming step for connection, the conductive coating film is on the exposed surface of the nth conductive coating film. It is characterized in that a conductive coating film for connection is formed in which the height from the green sheet is higher than the height from the green sheet of the nth ceramic coating film by applying a conductive paste only to the end of the substrate and drying. To do.

  In the manufacturing method of the multilayer inductor according to the present invention, the nth ceramic coating film is formed so as to cover the edge of the nth conductive coating film and to expose the upper surface other than the edge of the conductive coating film, The height of the nth ceramic coating film from the green sheet is higher than the height of the nth conductive coating film from the green sheet. Therefore, in comparison with the conventional manufacturing method in which the auxiliary magnetic material layer is formed so as to surround the conductor pattern, when the plurality of green sheets are stacked, the nth nth formed on one green sheet is formed. The area of contact between the ceramic coating and the other green sheet adjacent to the one green sheet increases, and the nth ceramic formed on the one green sheet by the edge of the nth conductive coating Combined with the fact that the coating film and the other green sheet adjacent to the one green sheet are more strongly pressed, delamination hardly occurs in the manufactured multilayer inductor. In the multilayer inductor manufacturing method according to the present invention, on the exposed surface of the nth conductive coating film, the height from the green sheet is higher than the height of the nth ceramic coating film from the green sheet. A conductive coating film is formed. Therefore, when a plurality of green sheets are stacked, another conductive green sheet adjacent to the green sheet is connected to the conductive conductive film formed on the exposed surface of the nth conductive film in the green sheet. By this conductive film for connection, the nth conductive film in one green sheet and the through hole formed in the other green sheet among the first conductive films in the other green sheet are filled. The connected portion is securely connected, and the connection reliability is greatly improved. Therefore, it is possible to achieve both suppression of delamination and reduction of connection failure.

  Preferably, the shrinkage rate at the time of firing the conductive conductive film for connection is smaller than the shrinkage rate at the time of firing the first to nth conductive paint films. If it does in this way, since it will become difficult to shrink | contract the conductive film for a connection at the time of baking, even after baking, the nth conductive film in one green sheet and the 1st conductive film in another green sheet The connection with the portion filled in the through hole formed in the other green sheet can be reliably maintained. As a result, connection failures can be further reduced.

  According to the present invention, it is possible to provide a multilayer inductor capable of achieving both suppression of delamination and reduction of connection failure and a method for manufacturing the same.

  Preferred embodiments of the present invention will be described with reference to the drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and a duplicate description is omitted.

(Configuration of multilayer inductor)
First, the configuration of the multilayer inductor 10 according to the present embodiment will be described with reference to FIGS. As shown in FIGS. 1 and 2, the multilayer inductor 10 includes a substantially rectangular parallelepiped multilayer body 12, a pair of external electrodes 14 and 16 formed on both side surfaces of the multilayer body 12 in the longitudinal direction, Inside the body 12, a conductor pattern C1 to C12 is provided with a coil L that is electrically connected to each other.

  The laminated body 12 has a pair of main surfaces 12a and 12b facing each other so as to be substantially parallel to each other. One of the main surfaces 12a and 12b is a surface facing the external substrate when the multilayer inductor 10 is mounted on the external substrate (not shown).

  As shown in FIG. 2, the laminated body 12 is formed by laminating magnetic layers A1 to A4, nonmagnetic layer B1, magnetic layers A5 to A7, nonmagnetic layer B2, and magnetic layers A8 to A12 in this order. It is composed by. That is, the upper surface of the magnetic layer A1 constitutes the main surface 12a of the multilayer body 12, the lower surface of the magnetic layer A12 constitutes the main surface 12b of the multilayer body 12 (see FIG. 2), and the main surfaces 12a and 12b. The facing direction (hereinafter referred to as the facing direction) of the laminated body 12 (hereinafter referred to as the stacking direction) of the stacked body 12 (magnetic layers A1 to A12 and nonmagnetic layers B1 and B2) in the present embodiment.

  The magnetic layers A1 to A12, the nonmagnetic layers B1 and B2, and magnetic films F1 to F10 described later function as an insulator having electrical insulation. The magnetic layers A1 to A12 and the magnetic films F1 to F10 may be formed using ferrite such as Ni—Cu—Zn based ferrite, Cu—Zn based ferrite, or Ni—Cu—Zn—Mg based ferrite, for example. it can. The nonmagnetic layers B1 and B2 can be formed using nonmagnetic ferrite such as Cu—Zn nonmagnetic ferrite, for example. In the actual multilayer inductor 1, the boundaries of the magnetic layers A1 to A12, the nonmagnetic layers B1 and B2, and the magnetic films F1 to F10 are integrated so as not to be visible.

  A conductor pattern C1 and a lead conductor D1 are formed on the surface of the magnetic layer A2. The conductor pattern C1 is disposed so as to be positioned at one end of the coil L. A lead conductor D1 is integrally formed at one end of the conductor pattern C1. The lead conductor D1 is drawn to the edge of the magnetic layer A2 on the side where the external electrode 12 is formed, and its end is exposed at the end face of the magnetic layer A2. For this reason, the conductor pattern C1 is electrically connected to the external electrode 12 through the lead conductor D1. The other end of the conductor pattern C1 is electrically connected to a columnar through-hole conductor E1 formed through the magnetic layer A2 in the thickness direction (that is, extending along the stacking direction). For this reason, the conductor pattern C1 is electrically connected to the corresponding conductor pattern C2 through the through-hole conductor E1 and the connection conductor G1 (described in detail later) in a stacked state.

  A conductor pattern C2 and a magnetic film F1 are formed on the surface of the magnetic layer A3. The conductor pattern C2 has a strip shape, corresponds to approximately one turn of the coil L, and is wound spirally on the magnetic layer A3. One end of the conductor pattern C2 is provided with a connection conductor G1 on the surface, and this connection conductor G1 is connected to the through-hole conductor E1 in a stacked state. That is, the conductor pattern C2 has an end connected to the through-hole conductor E1 via the connection conductor G1. The other end of the conductor pattern C2 is electrically connected to a columnar through-hole conductor E2 formed through the magnetic layer A3 in the thickness direction (that is, extending along the stacking direction). For this reason, the conductor pattern C2 is electrically connected to the corresponding conductor pattern C3 through the through-hole conductor E2 and the connection conductor G2 (details will be described later) in a stacked state.

  A conductor pattern C3 and a magnetic film F2 are formed on the surface of the magnetic layer A4. The conductor pattern C3 has a strip shape, corresponds to approximately one turn of the coil L, and is wound spirally on the magnetic layer A4. A connection conductor G2 is provided on one surface of the conductor pattern C3, and the connection conductor G2 is connected to the through-hole conductor E2 in a stacked state. That is, the conductor pattern C3 has an end connected to the through-hole conductor E2 via the connection conductor G2. The other end of the conductor pattern C3 is electrically connected to a cylindrical through-hole conductor E3 formed through the magnetic layer A4 in the thickness direction (that is, extending along the stacking direction). For this reason, the conductor pattern C3 is electrically connected to the corresponding conductor pattern C4 through the through-hole conductor E3 and the connection conductor G3 (details will be described later) in a stacked state.

  A conductor pattern C4 and a magnetic film F3 are formed on the surface of the nonmagnetic material layer B1. The conductor pattern C4 has a strip shape, which corresponds to approximately one turn of the coil L, and is wound spirally on the nonmagnetic layer B1. One end of the conductor pattern C4 is provided with a connection conductor G3 on its surface, and this connection conductor G3 is connected to the through-hole conductor E3 in a stacked state. That is, the conductor pattern C4 has an end connected to the through-hole conductor E3 through the connection conductor G3. The other end of the conductor pattern C4 is electrically connected to a columnar through-hole conductor E4 formed through the nonmagnetic layer B1 in the thickness direction (that is, extending along the stacking direction). For this reason, the conductor pattern C4 is electrically connected to the corresponding conductor pattern C5 through the through-hole conductor E4 and the connection conductor G4 (details will be described later) in a stacked state.

  A conductor pattern C5 and a magnetic film F4 are formed on the surface of the magnetic layer A5. The conductor pattern C5 has a strip shape, which corresponds to approximately one turn of the coil L, and is wound spirally on the magnetic layer A5. A connection conductor G4 is provided on the surface of one end of the conductor pattern C5, and this connection conductor G4 is connected to the through-hole conductor E4 in a stacked state. That is, the conductor pattern C5 has an end connected to the through-hole conductor E4 through the connection conductor G4. The other end of the conductor pattern C5 is electrically connected to a cylindrical through-hole conductor E5 formed through the magnetic layer A5 in the thickness direction (that is, extending along the stacking direction). Therefore, the conductor pattern C5 is electrically connected to the corresponding conductor pattern C6 through the through-hole conductor E5 and the connection conductor G5 (details will be described later) in a stacked state.

  A conductor pattern C6 and a magnetic film F5 are formed on the surface of the magnetic layer A6. The conductor pattern C6 has a strip shape, which corresponds to approximately one turn of the coil L, and is wound spirally on the magnetic layer A6. One end of the conductor pattern C6 is provided with a connection conductor G5 on its surface, and this connection conductor G5 is connected to the through-hole conductor E5 in a stacked state. That is, the conductor pattern C6 has an end connected to the through-hole conductor E5 through the connection conductor G5. The other end of the conductor pattern C6 is electrically connected to a columnar through-hole conductor E6 formed through the magnetic layer A6 in the thickness direction (that is, extending along the stacking direction). Therefore, the conductor pattern C6 is electrically connected to the corresponding conductor pattern C7 through the through-hole conductor E6 and the connection conductor G6 (described later in detail) in a stacked state.

  A conductor pattern C7 and a magnetic film F6 are formed on the surface of the magnetic layer A7. The conductor pattern C7 has a strip shape, which corresponds to approximately one turn of the coil L, and is wound spirally on the magnetic layer A7. One end of the conductor pattern C7 is provided with a connection conductor G6 on its surface, and this connection conductor G6 is connected to the through-hole conductor E6 in a stacked state. That is, the conductor pattern C7 has an end connected to the through-hole conductor E6 via the connection conductor G6. The other end of the conductor pattern C7 is electrically connected to a columnar through-hole conductor E7 formed through the magnetic layer A7 in the thickness direction (that is, extending along the stacking direction). For this reason, the conductor pattern C7 is electrically connected to the corresponding conductor pattern C8 through the through-hole conductor E7 and the connection conductor G7 (described in detail later) in a stacked state.

  A conductor pattern C8 and a magnetic film F7 are formed on the surface of the nonmagnetic material layer B2. The conductor pattern C8 has a strip shape, corresponds to approximately one turn of the coil L, and is wound spirally on the nonmagnetic layer B2. One end of the conductor pattern C8 is provided with a connection conductor G7 on its surface, and this connection conductor G7 is connected to the through-hole conductor E7 in a stacked state. That is, the conductor pattern C8 has an end connected to the through-hole conductor E7 via the connection conductor G7. The other end of the conductor pattern C8 is electrically connected to a columnar through-hole conductor E8 formed through the nonmagnetic layer B2 in the thickness direction (that is, extending along the stacking direction). For this reason, the conductor pattern C8 is electrically connected to the corresponding conductor pattern C9 through the through-hole conductor E8 and the connection conductor G8 (details will be described later) in a stacked state.

  A conductor pattern C9 and a magnetic film F8 are formed on the surface of the magnetic layer A8. The conductor pattern C9 has a strip shape, corresponds to approximately one turn of the coil L, and is wound spirally on the magnetic layer A8. One end of the conductor pattern C9 is provided with a connection conductor G8 on its surface, and this connection conductor G8 is connected to the through-hole conductor E8 in a stacked state. That is, the conductor pattern C9 has an end connected to the through-hole conductor E8 via the connection conductor G8. The other end of the conductor pattern C9 is electrically connected to a cylindrical through-hole conductor E9 formed through the magnetic layer A8 in the thickness direction (that is, extending along the stacking direction). For this reason, the conductor pattern C9 is electrically connected to the corresponding conductor pattern C10 through the through-hole conductor E9 and the connection conductor G9 (described in detail later) in a stacked state.

  A conductor pattern C10 and a magnetic film F9 are formed on the surface of the magnetic layer A9. The conductor pattern C10 has a strip shape, corresponds to approximately one turn of the coil L, and is wound spirally on the magnetic layer A9. One end of the conductor pattern C10 is provided with a connection conductor G9 on its surface, and this connection conductor G9 is connected to the through-hole conductor E9 in a stacked state. That is, the conductor pattern C10 has an end connected to the through-hole conductor E9 via the connection conductor G9. The other end of the conductor pattern C10 is electrically connected to a columnar through-hole conductor E10 formed through the magnetic layer A9 in the thickness direction (that is, extending along the stacking direction). For this reason, the conductor pattern C10 is electrically connected to the corresponding conductor pattern C11 through the through-hole conductor E10 and the connection conductor G10 (details will be described later) in a stacked state.

  A conductor pattern C11 and a magnetic film F10 are formed on the surface of the magnetic layer A10. The conductor pattern C11 has a strip shape, which corresponds to approximately 3/8 turn of the coil L, and is formed in an L shape on the magnetic layer A10. One end of the conductor pattern C11 is provided with a connection conductor G10 on the surface thereof, and this connection conductor G10 is connected to the through-hole conductor E10 in a stacked state. That is, the conductor pattern C11 has an end connected to the through-hole conductor E10 via the connection conductor G10. The other end of the conductor pattern C11 is electrically connected to a columnar through-hole conductor E11 formed through the magnetic layer A10 in the thickness direction (that is, extending along the stacking direction). For this reason, the conductor pattern C11 is electrically connected to the corresponding conductor pattern C12 through the through-hole conductor E11 in a stacked state.

  A conductor pattern C12 and a lead conductor D2 are formed on the surface of the magnetic layer A11. One end of the conductor pattern C12 includes a region electrically connected to the through-hole electrode E11 in a stacked state. A lead conductor D2 is integrally formed at the other end of the conductor pattern C12. The lead conductor D2 is drawn to the edge of the magnetic layer A11 on the side where the external electrode 14 is formed, and its end is exposed at the end face of the magnetic layer A11. For this reason, the conductor pattern C12 is electrically connected to the external electrode 14 through the lead conductor D2.

  Here, the configuration of the conductor patterns C2 to C11 will be described in more detail with reference to FIGS. 3 to 5 show only a part of the conductor patterns C2 to C11, the configurations of the conductor patterns C2 to C11 described below are common.

  The conductor patterns C2 to C11 are set to have a thickness of 20 μm or more, and are preferably set to have a thickness of about 40 μm to 80 μm. When the thickness of the conductor patterns C2 to C11 is less than 20 μm, the cross sectional area of the conductor patterns C2 to C11 tends to be relatively small, and the DC resistance value of the multilayer inductor 10 tends to be large. 10 is not suitable for high current applications.

  The conductor patterns C2 to C11 include a pair of wide surfaces S1 and S2 that face each other in the stacking direction, and a peripheral side surface S3 that connects the wide surface S1 and the wide surface S2 over the entire circumference of the pair of wide surfaces S1 and S2. Have. The conductor patterns C2 to C11 are arranged in the laminate 12 so that the wide surface S1 is close to the main surface 12a and the wide surface S2 is close to the main surface 12b (see particularly FIG. 4).

  As shown in FIGS. 3 to 5, the peripheral side surface S3 of the conductor patterns C2 to C11 is an uneven surface in which the concave portions 18a and the convex portions 18b are alternately arranged in the stacking direction. The concave portion 18a and the convex portion 18b extend along the circumferential direction of the peripheral side surface S3 over the entire circumference of the peripheral side surface S3. As shown in FIGS. 4 and 5, a part of the laminated body 12 (magnetic films F <b> 1 to F <b> 10) enters the recess 18 a. Therefore, as shown in FIG. 5, the conductor patterns C2 to C11 and the portions of the laminate 12 (magnetic films F1 to F10) that have entered the recess 18a and the conductor patterns C2 to C11 when viewed from the lamination direction. And a non-overlapping part 20b which is a part other than the overlapping part 20a. On the other hand, the convex part 18b has a tapered tip. The tip of the convex portion 18b substantially coincides with the edges of the wide surfaces S1, S2 when viewed from the stacking direction. Therefore, the bottom of the recess 18a overlaps the wide surfaces S1 and S2 when viewed from the stacking direction.

  The width W1 (see FIG. 5) of the conductor patterns C2 to C11 is set to be larger than 60 μm, and is preferably set to be about 200 μm to 300 μm. The width W2 (see FIG. 5) of the overlapping portion 20a is set to be 20 μm or more and smaller than the width W3 (see FIG. 5) of the non-overlapping portion 20b. When the width W2 of the overlapping portion 20a is less than 20 μm, the anchor effect (an effect that makes it difficult for the laminated body 12 to be peeled off from the uneven peripheral side surface S3) is exhibited sufficiently. There is a tendency not to be. When the width W2 of the overlapping portion 20a is equal to or larger than the width W3 of the non-overlapping portion 20b, the cross-sectional areas of the conductor patterns C2 to C11 are relatively small, and the DC resistance value of the multilayer inductor 10 tends to increase. Such a multilayer inductor 10 is not suitable for large current applications.

  Of the wide surface S1 of the conductor patterns C2 to C11, the region S1a in the overlapping portion 20a is in contact with the multilayer body 12 (magnetic films F1 to F10) as shown in FIG. On the other hand, the region S1b in the non-overlapping portion 20b of the wide surface S1 of the conductor patterns C2 to C11 is not in contact with the multilayer body 12 (magnetic films F1 to F10) as shown in FIG. In addition, a portion corresponding to the through-hole conductors E1 to E10 in the region S1b has a columnar shape or a truncated hemispherical shape, and is larger than the through-hole conductors E1 to E10 when viewed from the stacking direction. To G10 are arranged. That is, the connection conductors G1 to G10 are provided only at the ends of the conductor patterns C2 to C11. Note that a gap V is formed between a part of the region S1b (that is, a region indicated by hatching in FIG. 3) excluding the portion where the connection conductors G1 to G10 are disposed and the multilayer body 12. (See FIG. 5).

  The wide surface S2 of the conductor patterns C2 to C11 is in contact with the multilayer body 12 as shown in FIGS.

  The conductor patterns C1 to C12 and the lead conductors D1 and D2 described above can be formed using a metal material such as Ag, for example. The conductor patterns C1 and C12 and the lead conductors D1 and D2 can be set to have a thickness of about 10 μm to 25 μm, and the conductor patterns C1 and C12 can be set to have a width of about 200 μm to 300 μm. can do.

(Manufacturing method of multilayer inductor)
Subsequently, a method for manufacturing the multilayer inductor 10 according to the present embodiment will be described with reference to FIGS. 6 to 9 show only a part of a magnetic green sheet GS1 and a non-magnetic green sheet GS2, which will be described later, but will be described later on the magnetic green sheet GS1 or on the non-magnetic green sheet GS2. The steps of forming the conductive coatings H1 to H4 and the magnetic coatings I1 to I4 are common.

  First, a magnetic slurry, a non-magnetic slurry, a conductor paste, and a connecting conductor paste are prepared. Specifically, the magnetic slurry is, for example, a magnetic powder such as Ni-Cu-Zn ferrite powder, Cu-Zn ferrite powder or Ni-Cu-Zn-Mg ferrite powder is kneaded together with a binder and a solvent. It is obtained by doing. The nonmagnetic material slurry is obtained, for example, by kneading nonmagnetic material powder such as Cu—Zn-based nonmagnetic ferrite powder together with a binder and a solvent. The conductor paste and the connecting conductor paste are prepared, for example, by blending a conductor powder together with a binder and an organic solvent at a predetermined ratio and then kneading. As the conductor powder, Ag, an Ag alloy, Cu, Cu alloy, or the like can be usually used, but it is more preferable to use Ag having a low resistivity. In addition, a three-roll, a homogenizer, a sand mill, etc. can be used for kneading | mixing. Moreover, in order to make the shrinkage ratio after firing of the conductor paste for connection lower than the shrinkage ratio after firing of the conductor paste, for example, the type and amount of the binder and the solvent are changed between the conductor paste and the conductor paste for connection. Yes.

  Subsequently, for example, using a doctor blade method or a printing method, the magnetic material slurry is applied onto a support such as a PET film to form the magnetic material green sheet GS1 (see FIG. 9) to be the magnetic material layers A1 to A12. . Further, for example, by using a doctor blade method or a printing method, a nonmagnetic material slurry is applied on a support such as a PET film to form a nonmagnetic material green sheet GS2 (FIGS. 6 to 9) to become nonmagnetic material layers B1 and B2. Reference). The thickness of the magnetic green sheet GS1 and the non-magnetic green sheet GS2 can be set to about 10 μm to 30 μm, for example. Then, through holes (through holes) TH (see FIG. 9) penetrating the magnetic green sheet GS1 and the non-magnetic green sheet GS2 in the thickness direction are formed at predetermined positions by laser processing or the like, and conductors are formed in the through holes TH. Fill with paste.

  Subsequently, a conductive paste is applied in a predetermined pattern on the magnetic green sheet GS1 to be the magnetic layer A2, and dried at about 40 ° C. to 80 ° C. for less than 1 hour, whereby the conductive pattern C1 and the lead conductor D1 A band-shaped conductive coating film is formed. Similarly, a conductive paste is applied in a predetermined pattern on the magnetic green sheet GS1 serving as the magnetic layer A11 and dried to form a strip-shaped conductive coating film serving as the conductor pattern C12 and the lead conductor D2. The conductive coating film that becomes the conductor patterns C1, C12 and the lead conductors D1, D2 can have a thickness of about 10 μm to 25 μm. The conductive coating film that becomes the conductor patterns C1, C12 The width can be set to about 200 μm to 300 μm.

  Subsequently, on the magnetic green sheet GS1 to be the magnetic layers A3 to A10 and on the nonmagnetic green sheet GS2 to be the nonmagnetic layers B1 and B2, the conductive coating film and the magnetic film to be the conductor patterns C2 to C11 Magnetic coating films to be F1 to F10 are formed. Specifically, first, as shown in FIG. 6, the conductor pastes are respectively formed on the magnetic green sheets GS1 to be the magnetic layers A3 to A10 and the nonmagnetic green sheets GS2 to be the nonmagnetic layers B1 and B2. The belt-shaped conductive coating film H1 is formed by applying in a predetermined pattern and drying at about 40 ° C. to 80 ° C. for less than 1 hour. The thickness of the conductive coating film H1 can be set to about 15 μm to 30 μm, and the width can be set to about 200 μm to 300 μm.

  Then, the magnetic material slurry is applied so as to cover the edge H1a of the conductive coating film H1 and expose the upper surface of the central portion H1b other than the edge H1a of the conductive coating film H1, and at about 40 ° C. to 80 ° C. for 1 hour. The magnetic coating film I1 is formed by drying less. The thickness of the magnetic coating film I1 is set to be larger than the thickness of the conductive coating film H1, and is preferably set to about 20 μm to 40 μm. That is, the height of the magnetic coating film I1 from the magnetic green sheet GS1 or the nonmagnetic green sheet GS2 is higher than the height of the conductive coating film H1 from the magnetic green sheet GS1 or the nonmagnetic green sheet GS2. ing.

  The width T1 of the edge H1a of the conductive coating film H1 is preferably set to about 20 μm to 40 μm. The width T2 of the central portion H1b of the conductive coating film H1 is preferably set to about 150 μm to 270 μm.

  Next, as shown in FIG. 7, a conductive paste is applied in the same pattern as the conductive coating film H1 on the exposed surface of the conductive coating film H1 and the magnetic coating film I1, and at about 40 ° C. to 80 ° C. By drying for less than 1 hour, a strip-like conductive coating film H2 is formed. The conductive coating film H2 can be set to have the same thickness and width as the conductive coating film H1.

  Then, the magnetic material slurry is applied so as to cover the edge H2a of the conductive coating film H2 and to expose the upper surface of the central portion H2b other than the edge H2a of the conductive coating film H2, and at about 40 ° C. to 80 ° C. for 1 hour. The magnetic coating film I2 is formed by drying less. The thickness of the magnetic coating film I2 is set to be larger than the thickness of the conductive coating film H2, and is preferably set to be approximately the same as the thickness of the magnetic coating film I1. That is, the height of the magnetic coating film I2 from the magnetic green sheet GS1 or the nonmagnetic green sheet GS2 is higher than the height of the conductive coating film H2 from the magnetic green sheet GS1 or the nonmagnetic green sheet GS2. ing.

  Next, as shown in FIG. 7, similarly to the conductive coating film H2 and the magnetic coating film I2, the conductive coating film H3, the magnetic coating film I3, the conductive coating film H4, and the magnetic coating film I4 are arranged in this order. Form. Therefore, the height of the magnetic coating film I4 located at the uppermost position among the magnetic coating films I1 to I4 from the magnetic green sheet GS1 or the nonmagnetic green sheet GS2 is the uppermost position among the conductive coating films H1 to H4. The height of the conductive coating film H4 located at the height from the magnetic green sheet GS1 or the non-magnetic green sheet GS2 is higher.

  Subsequently, as shown in FIG. 8, a conductive paste for connection is applied on the exposed surface of the conductive coating film H4 located at the uppermost position among the conductive coating films H1 to H4 so as to form a hemispherical shape. The conductive coating film H5 for connection is formed by drying at about ~ 80 ° C for less than 1 hour. In other words, the conductive conductive film H5 for connection is not applied on the magnetic coating film I4 and is formed only at the end of the conductive coating film H4.

  The height of the conductive conductive film H5 for connection from the magnetic green sheet GS1 or the non-magnetic green sheet GS2 is the magnetic green sheet GS1 of the magnetic coating film I4 located at the uppermost position among the magnetic coating films I1 to I4. Alternatively, the height is higher than the height from the nonmagnetic green sheet GS2. The thickness of the conductive conductive film H5 for connection can be set to about 10 μm to 30 μm.

  Subsequently, the magnetic green sheet GS1 to be the magnetic layers A1 to A12 and the nonmagnetic green sheet GS2 to be the nonmagnetic layers B1 and B2 are stacked in the order shown in FIG. 2, and pressure is applied in the stacking direction. To form a green sheet laminate (not shown). At this time, as shown in FIG. 9, the conductive conductive film H5 for connection is crushed by another green sheet adjacent in the laminating direction, and the conductive conductive film H5 for connection and the conductive conductive film H1 in the other green sheet Of these, the portion filled in the through hole TH of the other green sheet is connected.

  Subsequently, the green sheet laminate is cut into units of chips, and then fired at about 850 ° C. to 900 ° C. for 10 hours or more to produce the laminate 12. For example, the length of the laminate 12 in the longitudinal direction after firing is approximately 2.5 mm, the width is approximately 2.0 mm, and the height is approximately 1.0 mm. Thus, the magnetic green sheet GS1 becomes each magnetic layer A1 to A12, the nonmagnetic green sheet GS2 becomes each nonmagnetic layer B1, B2, and the conductive coating H1 to H4 becomes each conductor pattern C2 to C11. The magnetic coating films I1 to I4 become the magnetic films F1 to F10, and the connecting conductive coating film H5 becomes the connection conductors G1 to G10. In addition, the shrinkage | contraction rate at the time of baking of an electrically conductive coating film is set to about 15%-25%, for example, and the shrinkage ratio at the time of baking of each green sheet GS1, GS2 and a magnetic body coating film is about 10%-about 20%. Is set to Further, since the conductive paste and the conductive paste for connection are different as described above, the shrinkage rate during firing of the conductive conductive film H5 for connection is smaller than the shrinkage rate during firing of the conductive paint film. Yes.

  Subsequently, external electrodes 14 and 16 are formed on the laminate 12. As a result, the multilayer inductor 10 is formed. The external electrodes 14 and 16 are baked at a predetermined temperature (for example, 700 to 800 ° C.) after transferring a conductor paste mainly composed of Ag, Cu, or Ni to both side surfaces of the laminate 12 in the longitudinal direction, It is formed by plating. For electroplating, for example, Cu, Ni and Sn can be used.

(Function)
By the way, in the conventional method of manufacturing a multilayer inductor, an auxiliary magnetic material layer that surrounds the conductor pattern and is thicker than the conductor pattern is formed on the magnetic green sheet. However, in the multilayer inductor manufactured as described above, one of the wide surfaces of the strip-shaped conductor pattern is separated from the multilayer body. For this reason, conductor patterns adjacent in the stacking direction are not electrically connected by the through-hole conductor, and connection failure may occur.

  On the other hand, it is also conceivable to form an auxiliary magnetic material layer that surrounds the conductor pattern and is thinner than the conductor pattern on the magnetic green sheet. However, in this case, the entire green sheet laminate in which the green sheets are laminated cannot be uniformly crimped, and there is a problem that delamination occurs in the manufactured multilayer inductor.

  These will be described in the light of this embodiment as follows. That is, the uppermost position of the conductive coating film H4 among the conductive coating films H1 to H4 from the magnetic green sheet GS1 or the nonmagnetic green sheet GS2 and the uppermost position of the magnetic coating films I1 to I4. The difference between the height of the magnetic coating film I4 from the magnetic green sheet GS1 or the nonmagnetic green sheet GS2 is the amount of protrusion X of the conductive coating film H4 from the magnetic coating film I4 (see FIG. 10A). 10), as shown in FIG. 10B, the smaller the protrusion amount X, the lower the delamination rate, but the higher the disconnection rate, while the larger the protrusion amount X, the more the wire breakage occurs. Although the generation rate decreases, the delamination generation rate increases. Therefore, conventionally, it has been difficult to achieve both suppression of delamination and reduction of connection failure.

  However, in the present embodiment as described above, the magnetic coating films I1 to I4 are respectively covered so as to cover the edges of the conductive coating films H1 to H4 and to expose the upper surfaces other than the edges of the conductive coating films H1 to H4. The height of the magnetic coating film I4 from the magnetic green sheet GS1 or the nonmagnetic green sheet GS2 is higher than the height of the conductive coating film H4 from the magnetic green sheet GS1 or the nonmagnetic green sheet GS2. It is high. Therefore, since the protrusion amount X becomes small, the area where the magnetic coating film I4 formed on one green sheet and another green sheet adjacent to the one green sheet increase, and the conductive coating film Combined with the fact that the magnetic coating film I4 and other green sheets are more strongly pressed by the edge of H4, delamination does not easily occur in the multilayer inductor 10. Moreover, in this embodiment, the conductive film H5 for connection is formed on the exposed surface of the conductive film H4 located in the uppermost position among the conductive films H1 to H4, and the magnetic property of the conductive film H5 for connection is formed. The height from the green body sheet GS1 or the nonmagnetic body green sheet GS2 is higher than the height from the magnetic body sheet GS1 or the nonmagnetic body green sheet GS2 of the magnetic coating film I4. Therefore, when the magnetic green sheet GS1 to be the magnetic layers A1 to A12 and the nonmagnetic green sheet GS2 to be the nonmagnetic layers B1 and B2 are laminated in the order shown in FIG. The conductive coating film H5 for connection, which is crushed by another green sheet adjacent in the stacking direction, and the portion filled in the through hole TH of the other green sheet in the conductive coating film H1 in the other green sheet. It is securely connected and connection reliability is greatly improved. Therefore, it is possible to achieve both suppression of delamination and reduction of connection failure.

  Moreover, in this embodiment, the shrinkage rate at the time of baking of the conductive film H5 for connection is smaller than the shrinkage rate at the time of baking of the conductive film. For this reason, the conductive conductive film H5 for connection is less likely to shrink during firing. Therefore, even after firing, the conductive paint film H4 on one green sheet and the other conductive sheets H1 on the other green sheets can be applied to other green sheets. The connection with the portion filled in the formed through hole TH can be reliably maintained. As a result, connection failures can be further reduced.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments. For example, in the present embodiment, the laminate 12 is composed of the magnetic layers A1 to A12 and the nonmagnetic layers B1 and B2. However, the present invention is not limited to this, and the entirety may be composed of a magnetic material. You may be comprised with the nonmagnetic material. However, from the viewpoint of further improving the DC superposition characteristics by suppressing the magnetic saturation and suppressing the decrease in the inductance value when a large current is passed, the magnetic layer A4 and the magnetic layer A4 are magnetically The laminated body 12 is preferably configured in such a manner that the nonmagnetic layer B1 is interposed between the magnetic layer A5 and the nonmagnetic layer B2 is interposed between the magnetic layer A7 and the magnetic layer A8. .

  In this embodiment, since the hemispherical conductive conductive film H5 is formed, the connection conductors G1 to G10 are columnar or truncated hemispherical. However, the present invention is not limited to this. That is, the connection conductors G1 to G10 can have various shapes such as a quadrangular prism shape, a truncated quadrangular pyramid shape (quadratic pyramid shape), a triangular prism shape, and a truncated triangular pyramid shape (triangular frustum shape).

  In the present embodiment, the conductive coating films H1 to H4 and the magnetic coating films I1 to I4 are alternately formed by four layers. From the viewpoint of improving the connection reliability by the connection conductors G1 to G10, the conductive coating films and What is necessary is just to form one or more magnetic coating films alternately.

  In the present embodiment, the convex portion 18b of the peripheral side surface S3 has a tapered shape that is sharpened toward the direction away from the conductor patterns C2 to C11. However, if the peripheral side surface S3 is an uneven surface, the convex portion 18b may not be sharpened.

FIG. 1 is a perspective view showing a multilayer inductor according to the present embodiment. FIG. 2 is an exploded perspective view for explaining the configuration of the multilayer body included in the multilayer inductor according to the present embodiment. FIG. 3 is an exploded perspective view showing a part of FIG. 2 in an enlarged manner. FIG. 4 is a cross-sectional view showing the stacked body taken along line IV-IV in FIG. FIG. 5 is an enlarged cross-sectional view of a part of FIG. FIG. 6 is a diagram illustrating a process for manufacturing the multilayer inductor according to the present embodiment. FIG. 7 is a view showing a step subsequent to FIG. FIG. 8 is a diagram showing a step subsequent to FIG. FIG. 9 is a diagram showing a step subsequent to FIG. (A) of FIG. 10 is a figure for demonstrating the protrusion amount X of a conductor coating film, (b) of FIG. 10 is the relationship between the protrusion amount X of a conductor coating film, a disconnection generation rate, and a crack generation rate. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Multilayer inductor, 12 ... Laminated body, 12a, 12b ... Main surface, 14, 16 ... External electrode, A1-A12 ... Magnetic body layer, B1, B2 ... Nonmagnetic body layer, C1-C12 ... Conductor pattern, E1 ~ E11 ... through-hole conductor, F1-F10 ... magnetic film, G1-G10 ... connecting conductor, H1-H4 ... conductive film, H5 ... conductive film for connection, I1-I4 ... magnetic film, TH ... through Hall, V ... Void.

Claims (5)

A laminate formed by laminating a plurality of insulator layers;
First and second external electrodes respectively disposed on the outer surface of the laminate;
A plurality of strip-shaped conductor patterns are configured to be electrically connected to each other, and a coil disposed inside the laminate,
A first lead conductor electrically connected to one end of the coil and electrically connected to the first outer conductor;
A second lead conductor electrically connected to the other end of the coil and electrically connected to the second external electrode;
The conductor pattern has first and second wide surfaces facing each other in the stacking direction of the stacked body,
A part of the laminate is disposed on an edge of the conductor pattern on the first wide surface side,
By arranging a part of the multilayer body at the edge, the conductor pattern has a portion disposed at the edge and the conductor pattern when viewed from the stacking direction. And overlapping portions and non-overlapping portions other than the overlapping portions,
A gap is formed between a part of the region in the non-overlapping portion of the first wide surface and the laminate,
The conductor pattern has an end connected to a through-hole conductor extending along the stacking direction,
The conductor pattern and the through-hole conductor are connected via a connection conductor provided only at the end of the conductor pattern,
The connection conductor is larger than the through-hole conductor when viewed from the stacking direction, and is disposed in a region in the non-overlapping portion of the first wide surface. Type inductor. A green sheet preparation process for preparing a green sheet;
A through hole forming step for forming a through hole penetrating in the thickness direction in the green sheet;
A conductive coating film forming step for forming a belt-shaped conductive coating film by filling the through-hole with the conductive paste and applying the conductive paste in a predetermined pattern on the green sheet and drying the conductive paste;
A ceramic slurry is applied and dried so as to cover an edge of the conductive coating and expose an upper surface other than the edge of the conductive coating, so that the height from the green sheet is the height of the conductive coating. A ceramic coating film forming step for forming a ceramic coating film higher than the height from the green sheet;
By applying and drying a conductive paste only on the exposed surface of the conductive coating film and on the edge of the conductive coating film, the height from the green sheet is high from the green sheet of the ceramic coating film. And a connecting conductive coating film forming step for forming a higher connecting conductive coating film.   3. The method for manufacturing a multilayer inductor according to claim 2, wherein a shrinkage rate during firing of the conductive conductive film for connection is smaller than a shrinkage rate during firing of the conductive paint film. A green sheet preparation process for preparing a green sheet;
A through hole forming step for forming a through hole penetrating in the thickness direction in the green sheet;
A first conductive coating film forming step of forming a strip-shaped first conductive coating film by filling the through-hole with a conductive paste and applying and drying the conductive paste on the green sheet in a predetermined pattern; ,
The ceramic slurry is applied and dried so as to cover the edge portion of the first conductive coating film and to expose the upper surface other than the edge portion of the first conductive coating film, so that the height from the green sheet is increased. A first ceramic coating film forming step of forming a first ceramic coating film higher than a height of the first conductive coating film from the green sheet;
An nth conductive coating film forming step of forming a strip-shaped nth (where n is an integer of 2 or more) conductive coating film;
An nth ceramic coating film forming step of forming an nth ceramic coating film;
A conductive coating film forming step for connection,
In the nth conductive coating film forming step, the predetermined pattern is formed on the exposed surface of the mth conductive coating film (where m is an integer satisfying m = n−1) and the mth ceramic coating film. The conductive paste is applied and dried, and when overlapped with the mth conductive coating film when viewed from the stacking direction, the height from the green sheet is from the green sheet of the mth ceramic coating film. Forming the nth conductive coating film so as to be higher than the height;
In the n-th ceramic coating film forming step, the ceramic slurry is applied and dried so as to cover an edge portion of the n-th conductive coating film and expose an upper surface other than the edge portion of the n-th conductive coating film. Then, the n-th ceramic coating film is formed so that the height from the green sheet is higher than the height of the n-th conductive coating film from the green sheet,
In the connecting conductive coating film forming step, a conductive paste is applied only to an end portion of the conductive coating film on the exposed surface of the n-th conductive coating film and dried, so that the height from the green sheet is increased. A method for manufacturing a multilayer inductor, comprising: forming the connection conductive coating film having a height higher than a height of the nth ceramic coating film from the green sheet.   5. The multilayer inductor according to claim 4, wherein a shrinkage ratio during firing of the connection conductive coating film is smaller than a shrinkage ratio during firing of the first to nth conductive paint films. Method.

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