JP2014187236A - Mounting structure of multilayer capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer capacitor in which audible sound can be reduced while obtaining high degree of freedom in circuit design, and to provide a mounting structure of a multilayer capacitor.SOLUTION: When the deviation amount of a first end point 13s where a first outermost internal conductor 13x closest to the first principal surface 12a of a laminate 12, out of internal conductors 13, 15 embedded in the laminate 12 of a multilayer capacitor 10, reaches the side face 12s of the laminate 12, is H1, and the deviation of a second end point 15s where a second outermost internal conductor 15x closest to the second principal surface 12b of the laminate 12 facing the mounting surface 22s of a circuit board 22 reaches the side face 12t, is H2, following relation is satisfied: H1>H2. The multilayer capacitor 10 is mounted on the circuit board in a state where the second principal surface 12b of the laminate 12 faces the mounting surface of the circuit board.

Description

  The present invention relates to a multilayer capacitor mounting structure.

  In recent years, miniaturization and high performance of electronic devices are rapidly progressing, and the capacity of multilayer capacitors is increasing correspondingly. High dielectric constant ceramics such as barium titanate are used as dielectric ceramic materials for large-capacity multilayer capacitors. These high dielectric constant ceramics have piezoelectricity and electrostrictive properties. For this reason, when the ceramic body is composed of high dielectric constant ceramics, mechanical distortion occurs with application of voltage (electric field). Therefore, when an AC voltage or a DC voltage on which an AC component is superimposed is applied to this type of multilayer capacitor, vibration due to mechanical distortion occurs in the ceramic body. When the vibration is transmitted to the circuit board, the circuit board vibrates. When the vibration sound generated by the vibration of the circuit board is in the audible frequency range of 20 Hz to 20 kHz, it can be heard by the human ear as an unpleasant audible sound. This pronunciation phenomenon is called “acoustic noise”.

  Various proposals have heretofore been made in order to prevent and reduce such audible sounds.

  For example, Patent Document 1 proposes that ceramic capacitors 1A and 1B having the same specifications are arranged on the front surface 2a and the back surface 2b of the circuit board 2 so as to be plane-symmetrical as shown in FIG. In this technique, the vibration transmitted from one capacitor to the circuit board and the vibration transmitted from the other capacitor to the circuit board cancel each other, thereby reducing the generation of audible sound.

JP 2000-23320 A

  However, the mounting form described in Patent Document 1 has a problem in that the degree of freedom in circuit design is impaired because it is necessary to mount two multilayer capacitors of equivalent specifications on the front and back surfaces of the circuit board.

  In view of such circumstances, the present invention is intended to provide a multilayer capacitor and a multilayer capacitor mounting structure capable of reducing audible sound while obtaining a high degree of freedom in circuit design.

  In order to solve the above-mentioned problems, the present invention provides a multilayer capacitor mounting structure configured as follows.

  A multilayer capacitor mounting structure is a mounting structure in which a multilayer capacitor is mounted on a circuit board. The circuit board has a mounting surface on which first and second lands are formed. The multilayer capacitor includes a multilayer body and first and second external electrodes. The stacked body has a rectangular parallelepiped shape, and the surface of the stacked body forming the rectangular parallelepiped has first and second main surfaces facing each other, first and second side surfaces facing each other, and first surfaces facing each other. 3 and 4th side. The laminated body is disposed along (a) a dielectric layer in which the first and second main surfaces are opposed to each other, and (b) along the main surface of the dielectric layer. A first inner conductor extending to the side surface, and (c) a second inner conductor disposed along the main surface of the dielectric layer and extending to the second side surface. The first external electrode covers the first side surface of the multilayer body and is connected to the first internal conductor. The second external electrode covers the second side surface of the multilayer body and is connected to the second internal conductor. In a cross section orthogonal to the first and second side surfaces of the stacked body and orthogonal to the first and second main surfaces, the relationship of H1> H2 is satisfied. Here, (i) of the first and second inner conductors reaching the first side surface or the second side surface of the first outermost inner conductor closest to the first main surface. Between the first imaginary straight line passing through the first outermost point closest to the first main surface of the first outermost inner conductor and parallel to the first main surface. The distance is H1, and (ii) the first side surface or the second side surface of the second outermost inner conductor closest to the second main surface among the first and second inner conductors is reached. A second imaginary straight line passing through a second outermost point closest to the second main surface of the second outermost inner conductor and parallel to the second main surface. Let H2 be the distance between them. The first external electrode is fixed to the first land in a state where the second main surface of the laminated body faces the mounting surface of the circuit board, and the second external electrode is the second external electrode. It is fixed to the land.

  In the above configuration, when the relationship of H1> H2 is satisfied, the multilayer body of the multilayer capacitor is closer to the second principal surface side than the first principal surface side in the vicinity of the first and second side surfaces. Since it contains a lot of internal conductors, rigidity is increased and distortion is difficult. When the multilayer capacitor is mounted on the circuit board so that the second main surface of the multilayer body of the multilayer capacitor faces the mounting surface of the circuit board, distortion vibration occurs from the multilayer capacitor to the circuit board through the hard, hard-to-distort part. Is propagated. Therefore, compared to the case where the multilayer capacitor is mounted on the circuit board so that the first main surface of the multilayer body of the multilayer capacitor faces the mounting surface of the circuit board, distortion vibration propagated from the multilayer capacitor to the circuit board is small. Become. As a result, audible sound is reduced.

  Preferably, the surface of the multilayer body of the multilayer capacitor includes a curved surface that connects the first and second main surfaces and the first and second side surfaces. In the cross section of the laminate, (i) the radius of curvature of the first imaginary circle passing through the three ends of the cross section of the curved surface closest to the first end point is R1, and (ii) the first R1> R2, where R2 is the radius of curvature of the second imaginary circle passing through both ends and the center of the cross section of the curved surface closest to the end point of 2. The second outermost inner conductor is included in the region of the second virtual circle.

  In this case, since the second outermost inner conductor is included in the region of the second virtual circle, the multilayer body of the multilayer capacitor has a portion on the second main surface side near the first and second side surfaces. Since rigidity increases, it becomes difficult to distort. Since the distortion is propagated from the multilayer capacitor to the circuit board through the portion which is not easily distorted, the vibration of the distortion propagated to the circuit board is reduced. As a result, the audible sound is reduced in the multilayer capacitor mounting structure.

  In addition, the present invention provides a multilayer capacitor series configured as follows.

  The multilayer capacitor string includes: (a) a tape body in which a storage portion is formed; (b) a cover tape that is attached to the tape body and covers the storage portion; and (c) a multilayer capacitor that is stored in the storage portion. With. The multilayer capacitor includes a multilayer body and first and second external electrodes. The surface of the laminated body has a rectangular parallelepiped shape, and the surface of the laminated body forming the rectangular parallelepiped faces the first and second main surfaces facing each other and the first and second side surfaces facing each other. And third and fourth side surfaces. The laminated body is disposed along (a) a dielectric layer in which the first and second main surfaces are opposed to each other, and (b) along the main surface of the dielectric layer. A first inner conductor extending to the side surface, and (c) a second inner conductor disposed along the main surface of the dielectric layer and extending to the second side surface. The first external electrode covers the first side surface of the multilayer body and is connected to the first internal conductor. The second external electrode covers the second side surface of the multilayer body and is connected to the second internal conductor. In a cross section orthogonal to the first and second side surfaces of the stacked body and orthogonal to the first and second main surfaces, the relationship of H1> H2 is satisfied. Here, (i) of the first and second inner conductors reaching the first side surface or the second side surface of the first outermost inner conductor closest to the first main surface. Between the first imaginary straight line passing through the first outermost point closest to the first main surface of the first outermost inner conductor and parallel to the first main surface. The distance is H1, and (ii) the first side surface or the second side surface of the second outermost inner conductor closest to the second main surface among the first and second inner conductors is reached. A second imaginary straight line passing through the second outermost point closest to the second main surface of the second outermost inner conductor and parallel to the second main surface. Let H2 be the distance between. The multilayer capacitor is housed in the housing portion in a state where the first main surface of the multilayer body faces the cover tape.

  In the above configuration, by peeling the cover tape and adsorbing the first main surface of the multilayer capacitor multilayer body, the second main surface of the multilayer capacitor multilayer body faces the mounting surface of the circuit board. A multilayer capacitor can be mounted on a circuit board. Since the multilayer capacitors are housed in the same orientation, it is easy to mount the multilayer capacitors in a direction that reduces audible sound.

  Preferably, the surface of the multilayer body of the multilayer capacitor includes a curved surface that connects the first and second main surfaces and the first and second side surfaces. In the cross section of the laminate, (i) the radius of curvature of the first imaginary circle passing through the three ends of the cross section of the curved surface closest to the first end point is R1, and (ii) the first R1> R2, where R2 is the radius of curvature of the second imaginary circle passing through both ends and the center of the cross section of the curved surface closest to the end point of 2. The second outermost inner conductor is included in the region of the second virtual circle.

  The present invention also provides a method of manufacturing a multilayer capacitor configured as follows.

  The manufacturing method of the multilayer capacitor includes (i) a first step of stacking an unfired ceramic green sheet and a conductive pattern to form a mother laminate, and (ii) on one side of the mother laminate in the stacking direction. By placing the second member on the other side of the mother laminate in the laminating direction and sandwiching the mother laminate between the first and second members in a state of being in contact with the mother laminate. A second step of pressing the mother laminated body in the mother lamination direction; and (iii) a third step of cutting the pressed mother laminated body to produce individual laminated bodies. In the second step, by changing the elasticity of the first member and the second member, only one of the first and second conductive patterns is arranged when seen through in the stacking direction. A step in the stacking direction from the surface of the peripheral region to the surface in the stacking direction of the effective region in which both the first and second conductive patterns overlap is one side and the other side of the stack in the stacking direction. Make them different. As a preferred embodiment, in the second step, the first member is a resin film, and the second member is a mold.

  When a multilayer capacitor is manufactured by the above method, a multilayer capacitor in which audible sound is reduced when mounted on a circuit board can be manufactured.

  The present invention also provides a multilayer capacitor configured as follows.

  The multilayer capacitor includes a multilayer body and first and second external electrodes. The stacked body has a rectangular parallelepiped shape, and the surface of the stacked body forming the rectangular parallelepiped has first and second main surfaces facing each other, first and second side surfaces facing each other, and first surfaces facing each other. 3 and 4th side. The laminated body is disposed along (a) a dielectric layer in which the first and second main surfaces are opposed to each other, and (b) along the main surface of the dielectric layer. A first inner conductor extending to the side surface, and (c) a second inner conductor disposed along the main surface of the dielectric layer and extending to the second side surface. The first external electrode covers the first side surface of the multilayer body and is connected to the first internal conductor. The second external electrode covers the second side surface of the multilayer body and is connected to the second internal conductor. In a cross section orthogonal to the first and second side surfaces of the stacked body and orthogonal to the first and second main surfaces, the relationship of H1> H2 is satisfied. Here, (i) of the first and second inner conductors reaching the first side surface or the second side surface of the first outermost inner conductor closest to the first main surface. Between the first imaginary straight line passing through the first outermost point closest to the first main surface of the first outermost inner conductor and parallel to the first main surface. The distance is H1, and (ii) the first side surface or the second side surface of the second outermost inner conductor closest to the second main surface among the first and second inner conductors is reached. A second imaginary straight line passing through a second outermost point closest to the second main surface of the second outermost inner conductor and parallel to the second main surface. Let H2 be the distance between them.

  When the multilayer capacitor is mounted on a circuit board with the second main surface of the multilayer body facing the mounting surface of the circuit board, audible sound is reduced.

  According to the present invention, audible sound can be reduced while obtaining a high degree of freedom in circuit design.

It is a perspective view of the mounting structure of a multilayer capacitor. Example 1 It is sectional drawing of the mounting structure of a multilayer capacitor. Example 1 It is sectional drawing of a multilayer capacitor. Example 1 It is sectional drawing of the laminated body of a multilayer capacitor. Example 1 It is sectional drawing of the laminated body of a multilayer capacitor. Example 1 It is sectional drawing which shows the manufacturing process of a multilayer capacitor. Example 1 It is sectional drawing which shows the manufacturing process of a multilayer capacitor. Example 1 It is sectional drawing which shows the manufacturing process of a multilayer capacitor. (Modification 1) It is explanatory drawing of the measurement of a vibration sound (audible sound). Example 1 It is (a) top view, (b) sectional view, (c) sectional view of a multilayer capacitor series. (Example 2) It is sectional drawing of the mounting structure of a multilayer capacitor. (Conventional example)

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  Example 1 A mounting structure 20 of the multilayer capacitor 10 of Example 1 will be described with reference to FIGS.

  FIG. 1 is a perspective view schematically showing a mounting structure 20 of the multilayer capacitor 10. 2 is a cross-sectional view taken along line AA in FIG. FIG. 3 is a cross-sectional view of the multilayer capacitor 10.

  As shown in FIGS. 1 and 2, in the mounting structure 20 of the multilayer capacitor 10, the multilayer capacitor 10 is mounted on a circuit board 22. First and second lands 24 and 26 are formed on the mounting surface 22 s of the circuit board 22.

  The multilayer capacitor 10 includes a multilayer body 12, a first external electrode 14, and a second external electrode 16. The laminated body 12 has a rectangular parallelepiped shape. That is, the surface of the laminate 12 includes first and second main surfaces 12a and 12b facing each other, first and second side surfaces 12s and 12t facing each other, and third and fourth side surfaces facing each other. 12m, 12n. Here, the rectangular parallelepiped shape includes a shape in which corners and ridge lines are rounded. The first external electrode 14 covers the first side surface 12s of the multilayer body 12 and the vicinity thereof. The second external electrode 16 covers the second side surface 12t of the multilayer body 12 and the vicinity thereof.

  Specifically, as shown in FIGS. 2 and 3, in the multilayer capacitor 10, the corners of the multilayer body 12 are rounded. That is, the laminate 12 includes the first curved surfaces 12u and 12v that connect the first main surface 12a and the first and second side surfaces 12s and 12t, the second main surface 12b, and the first and second surfaces. The second curved surfaces 12w and 12x connecting the side surfaces 12s and 12t are included. These curved surfaces 12u, 12v, 12w, 12x are covered with the first and second external electrodes 14,16.

  The multilayer body 12 includes a first internal conductor 13 and a second internal layer between dielectric layers laminated in a direction in which the first and second main surfaces 12a and 12b face each other (vertical direction in the drawing). A conductor 15 is disposed. The first inner conductor 13 extends to the first side surface 12 s and is connected to the first outer electrode 14. The second inner conductor 15 extends to the second side surface 12 t and is connected to the second outer electrode 16. The second inner conductors 13 and 15 include inner conductors having effective portions in which the first inner conductor 13 and the second inner conductor 15 overlap each other. Although not shown, the first and second inner conductors 13 and 15 may include a conductor having no effective portion.

The dielectric layer of the laminate 12 is a ceramic dielectric, and contains BaTiO ₃ as a main component. The main component may be CaTiO ₃ , SrTiO ₃ , CaZrO ₃ or the like. Further, a Mn compound, Mg compound, Si compound, Co compound, Ni compound, rare earth compound, or the like may be added as a subcomponent of the ceramic powder.

  The first and second inner conductors 13 and 15 are, for example, Ni, Cu, Ag, Pd, an Ag—Pd alloy, Au, or the like.

  The first and second external electrodes 14 and 16 include, for example, a sintered metal layer and a plating layer, and the sintered metal layer is baked with a paste such as Cu, Ni, Ag, Pd, Ag-Pd alloy, Au, or the like. Formed by. A plated layer is formed on the sintered metal layer, and an Sn plated layer is formed on the Ni plated layer. The plating layer may be Cu plating or Au plating. Note that the first and second external electrodes 14 and 16 may have only a plated layer without a sintered metal layer.

  As shown in FIG. 3, the first and second inner conductors 13 and 15 extend in parallel to each other in an effective region 12 c that overlaps each other when seen through from the stacking direction (vertical direction in the drawing). . On the other hand, the first and second inner conductors 13 in the peripheral regions 12d and 12e where only one of the first inner conductor 13 and the second inner conductor 15 is disposed when seen through from the stacking direction. , 15 are curved.

  As shown in FIGS. 1 and 2, in the mounting structure 20, the multilayer capacitor 10 is mounted on the mounting surface 22 s of the circuit board 22. That is, the first external electrode 14 of the multilayer capacitor 10 is fixed to the first land 24 of the circuit board 22 via the bonding material 19, and the second external electrode 16 of the multilayer capacitor 10 is fixed to the first land 24 of the circuit board 22. 2 lands 26 are fixed.

  For example, the multilayer capacitor 10 is mounted on the first and second lands 24 and 26 to which the conductive adhesive or solder paste as the bonding material 19 is previously applied by a method such as screen printing, and then passed through a reflow furnace. . As a result, the bonding material 19 is melted, a fillet is formed on the multilayer capacitor 10, and the multilayer capacitor 10 is fixed to the circuit board 22.

  In the mounting structure 20, the second main surface 12 b of the multilayer body 12 of the multilayer capacitor 10 faces the circuit board 22 and the mounting surface 22 s and is parallel to the mounting surface 22 s. That is, the second main surface 12 b of the multilayer body 12 of the multilayer capacitor 10 is closer to the mounting surface 22 s of the circuit board 22 than the first main surface 12 a of the multilayer body 12 of the multilayer capacitor 10.

  When a voltage is applied to the multilayer capacitor 10 of the mounting structure 20, the dielectric layer of the multilayer body 12 has an electrostrictive effect, so that it is sandwiched between the inner conductors 13 and 15 in the effective region of the multilayer body 12 of the multilayer capacitor 10. The capacitance forming portion that expands in the stacking direction contracts in a direction perpendicular to the stacking direction. When this distortion is transmitted to the circuit board 22 through the bonding material 19, the circuit board 22 bends. In particular, since the second curved surfaces 12w and 12x and the vicinity thereof are on the strain transmission path to the circuit board 22, the distortions of the second curved surfaces 12w and 12x and the vicinity thereof from the external electrodes 14 and 16 are reduced. It is easy to be transmitted to the circuit board 22 through the bonding material 19.

  When an AC voltage is applied to the multilayer capacitor 10, the circuit board 22 may vibrate and sound may be generated. In particular, a phenomenon in which an audible sound that is audible to the human ear is generated is called “squeaking”. In order to reduce this audible sound, H1 and H2 shown in FIGS. 4 and 5 are configured to satisfy the relationship of H1> H2.

  4 and 5 are cross sections orthogonal to the first and second side surfaces 12s and 12t, and orthogonal to the first and second main surfaces 12a and 12b, in particular, the third side surface 12m and the fourth side of the laminate 12. The cross section which passes along the middle (namely, center of the laminated body 12) of the side surface 12n of this is shown. In H1, the first outermost inner conductor 13x closest to the first main surface 12a of the first and second inner conductors 13 and 15 reaches the first side surface 12s or the second side surface 12t. The first imaginary straight line L1 passing through the first end point 13s and the first outermost point 13t closest to the first major surface 12a of the first outermost inner conductor 13x and parallel to the first major surface 12a; , That is, the length of a perpendicular line drawn from the first end point 13s to the first virtual straight line L1. In H2, the second outermost inner conductor 15x closest to the second main surface 12b of the first and second inner conductors 13 and 15 reaches the first side surface 12s or the second side surface 12t. The second imaginary straight line L2 passing through the second end point 15s and the second outermost point 15t closest to the second major surface 12b of the second outermost inner conductor 15x and parallel to the second major surface 12b; , That is, the length of the perpendicular drawn from the second end point 15s to the second virtual straight line L2.

  When the relationship of H1> H2 is satisfied, the multilayer body 12 of the multilayer capacitor 10 has a second mounting side, which is the mounting side, compared to the first curved surfaces 12u and 12v on the first main surface 12a side and the vicinity thereof. Since the rigidity in the vicinity of the second curved surfaces 12w and 12x on the main surface 12b side is increased, the distortion is less likely to occur, and the vibration of the distortion transmitted to the circuit board is reduced.

  In addition, as shown in FIG. 5, the radius of curvature of the first virtual circle 11a passing through both ends and the central three points of the curved surface 12u closest to the first end point 15s is R1, and the second end point 15s When the radius of curvature of the second imaginary circle 11b passing through both ends and the central three points of the closest curved surface 12x is R2, R1> R2, and the second imaginary circle 11b has a second radius within the region of the second imaginary circle 11b. The outermost inner conductor 15x is included.

  By satisfying the relationship of R1> R2, the second curved surfaces 12w and 12x on the second main surface 12b side and the rigidity in the vicinity thereof are changed to the second curved surfaces 12u and 12v on the first main surface 12a side. The rigidity of the multilayer capacitor 10 of the multilayer capacitor 10 is higher than that of the vicinity thereof, and the rigidity is further increased by including the inner conductor in the vicinity of the second curved surfaces 12w and 12x. It becomes difficult and the vibration of the distortion propagated to the circuit board is reduced. As a result, audible sound is reduced.

  4 and 5, the multilayer capacitor 10 is polished and exposed from the third or fourth side surface 12m, 12n (see FIG. 1) side of the multilayer body 12 to the center of the multilayer body 12. Can be observed. H1, H2, R1, and R2 can be determined by measuring the polished and exposed cross section using an optical microscope.

  Next, a method for manufacturing the multilayer capacitor 10 will be described with reference to the cross-sectional views of FIGS.

  First, as shown in FIG. 6, an unfired ceramic green sheet 11 and a conductive pattern 17 are laminated to form a mother laminated body 50. The mother laminated body 50 is an aggregate of laminated bodies of multilayer capacitors, and individual laminated bodies are obtained by cutting the mother laminated body 50. In the mother multilayer body 50, the dielectric layer of the multilayer capacitor multilayer body is formed by the unfired ceramic green sheet 11, and the first and second internal conductors of the multilayer capacitor multilayer body are formed by the conductive pattern 17. The mother laminate 50 is formed by laminating ceramic green sheets, in which a conductive pattern to be the first or second internal conductor is formed on the ceramic green sheets by a method such as screen printing or gravure printing, in an appropriate order. To do.

  Next, as shown in FIG. 7, the mother laminate 50 is pressed using a mold unit 60. The mold unit 60 is fitted to the first mold 62, the second mold 64 facing the first mold 62, the first mold 62, and the second mold 64. And a third mold 66 surrounding the periphery.

  The mother laminated body 50 is disposed between the first mold 62 and the second mold 64, and the mother laminated body is interposed via the first and second sheet members 63 and 65 which are the first and second members. 50 is sandwiched between the first mold 62 and the second mold 64 to press the mother stacked body 50 in the stacking direction (vertical direction in the drawing). That is, first and second sheet members having elasticity, such as resin, between the laminate 50 and the first mold 62 and between the laminate 50 and the second mold 64, respectively. 63 and 65 are arranged, and the mother laminated body 50 is pressed in the laminating direction in a state where the first and second sheet members 63 and 65 are in contact with the mother laminated body 50. For the press, a method such as a rigid press that mechanically applies pressure or a hydrostatic press that applies hydraulic pressure is used.

  Next, the pressed mother laminate is divided into chips by a method such as pressing and dicing to obtain an unfired laminate. Thereafter, when the unsintered multilayer body is fired, the multilayer body of the multilayer capacitor is completed.

  Next, first and second external electrodes are formed on the laminate. For example, one of the first and second side surfaces of the laminate is held on the pressure-sensitive adhesive sheet, and the other side surface is immersed in a conductive paste and dried to form a metal layer. A metal layer is similarly formed on the other side surface. A sintered metal layer is formed by baking the metal layer. Furthermore, Ni plating and Sn plating are performed on the sintered metal layer.

  The multilayer capacitor is completed through the above steps.

  Note that the external electrode may be formed using a conductive resin paste. When the conductive resin paste is used, the resin attenuates the vibration and can effectively suppress the audible sound.

  The multilayer capacitor multilayer body has a large thickness in the stacking direction in the effective region where the first and second inner conductors face each other, and in the peripheral region where only one of the first and second inner conductors exists. The thickness in the stacking direction is reduced. Therefore, a thickness difference occurs in the multilayer capacitor multilayer body. In particular, in the case of a large-capacity multilayer capacitor of 1 μF or more, the number of first and second inner conductors increases, so that the thickness difference is large. Therefore, when a mother laminate in which conductive patterns to be the first and second inner conductors are arranged between the laminated unfired ceramic green sheets is pressed in the laminating direction using only a mold, the thickness in the laminating direction is reduced. In a small area, sufficient pressure may not be applied and adhesion may be insufficient. Therefore, when the laminated body is pressed in the laminating direction via the first and second sheet members having elasticity, it is possible to apply a sufficient pressure even in a region where the thickness is small to make it adhere.

  However, when pressed through the elastic first and second sheet members, the peripheral area of the mother laminated body is small in thickness (density), so that it is depressed by pressure, and the mother laminated body is divided by this depression. A curved surface is formed in the laminated body. The conductive pattern disposed between the unfired ceramic green sheets bends inward from a thick region in the stacking direction to a thin region. When the conductive pattern bends inward, in the laminate obtained by dividing the mother laminate, the internal conductor formed by the conductive pattern moves away from the curved surface. When the inner conductor moves away from the curved surface, the rigidity in the vicinity of the curved surface decreases. When the rigidity in the vicinity of the curved surface is reduced, the audible sound is increased when the multilayer capacitor is mounted on the circuit board.

  When the thickness and material of the first and second sheet members are appropriately selected, the curvature radius of the first curved surface in contact with the first sheet member (first member), and the second sheet member (second sheet) The curvature radius of the second curved surface in contact with the member can be made different. For example, when the elasticity of the second sheet member is smaller than the elasticity of the first sheet member, the radius of curvature of the second curved surface in contact with the second sheet member is the first radius in contact with the first sheet member. It becomes smaller than the radius of curvature of the curved surface. In this case, the rigidity in the vicinity of the curved surface having the smaller curvature radius is greater than that in the vicinity of the curved surface having the larger curvature radius. Therefore, when a multilayer capacitor is mounted on a circuit board so that the curved surface with the smaller radius of curvature faces the land of the circuit board, the multilayer capacitor is mounted so that the curved surface with the larger radius of curvature faces the land of the circuit board. Compared with mounting on a circuit board, audible sound is reduced.

  As shown in the cross-sectional view of FIG. 8, between the mother laminate 50 and the first mold 62 and between the mother laminate 50 and the second mold 64. Only, that is, the sheet member 65 (second member) is disposed only between the mother laminate 50 and the second mold 64, and one side in the lamination direction of the mother laminate 50 is in contact with the sheet member 65, and the mother laminate The mother stacked body 50 may be pressed in the stacking direction with the other side of the stacking direction 50 in contact with the mold 62. In this case, the mold 62 is the first member.

  In this case, the mother laminated body is pressed in the laminating direction in a state where the mold is in contact with one main surface of the main surfaces on both sides in the laminating direction. On one main surface side in contact with the mold, the bending of the conductive pattern that becomes the inner conductor is suppressed, and the curvature radius of the curved surface becomes smaller than when the sheet member is interposed in the laminate formed from the mother laminate, The phenomenon that the rigidity is reduced near the curved surface is suppressed. As a result, when the multilayer capacitor was mounted so that the main surface in contact with the mold faced the mounting surface of the circuit board, the multilayer capacitor was mounted so that the main surface in contact with the sheet member faced the mounting surface of the circuit board. Compared to the case, the audible sound is reduced. That is, the main surface in contact with the sheet member is the first main surface, and the main surface in contact with the mold is the second main surface of the laminate.

  In addition, since a sufficient pressure can be applied to the region where the thickness of the laminate is small through the sheet member in contact with the other main surface of the laminate, the adhesion between the dielectric layer and the first or second internal conductor Can be secured.

  <Experimental Example> An experimental example in which the vibration sound (or audible sound) of the circuit board 22 on which the multilayer capacitor 10 is mounted will be described with reference to the explanatory diagram of FIG.

  As shown in FIG. 9, a sample 28 having a multilayer capacitor 10 mounted on a circuit board 22 is prepared, the sample 28 is placed in an anechoic box 72, and an AC voltage having a frequency of 3 kHz and a voltage of 1 Vp-p is applied. Applied to the multilayer capacitor 10. The sound collecting microphone 74 was disposed so as to face the circuit board 22 and collected, and the collected sound pressure level was measured using the sound collecting device 76 and the FET analyzer 78.

  Sample 28 has a length (dimension between the first and second side surfaces) of 2.0 mm, a width (dimension between the third and fourth side surfaces) of 1.25 mm, and a thickness (between the main surfaces). A multilayer capacitor 10 having a dimension) of 0.85 mm is prepared, solder paste is applied onto the lands 24 and 26 formed on the mounting surface 22s of the circuit board 22, the multilayer capacitor 10 is mounted, and then passed through a reflow furnace. Then, the multilayer capacitor 10 was produced by fixing it to the circuit board 22. The sample of Example 1 in which the multilayer capacitor 10 is mounted on the circuit board 22 so that the second main surface of the multilayer body of the multilayer capacitor 10 faces the mounting surface 22s of the circuit board 22, and the multilayer body of the multilayer capacitor 10 Measurement was performed on the sample of Comparative Example 1 in which the multilayer capacitor 10 was mounted on the circuit board 22 so that the first main surface was opposed to the mounting surface 22 s of the circuit board 22. As a result of the measurement, the sound pressure level of the sample of Example 1 was lower than the sound pressure level of the sample of Comparative Example 1.

  Example 2 A multilayer capacitor series 30 of Example 2 will be described with reference to FIG. FIG. 10A is a plan view of the multilayer capacitor series 30. FIG.10 (b) is sectional drawing cut | disconnected along line BB of Fig.10 (a). FIG.10 (c) is sectional drawing cut | disconnected along line CC of Fig.10 (a).

  As shown in FIGS. 10A and 10B, the multilayer capacitor series 30 includes a carrier tape 31 having a cover tape 34 attached to a tape body 32 and the multilayer capacitor 10 of the first embodiment. The tape body 32 has an elongated shape. The tape body 32 is formed with a feed hole 30x for conveyance and a recess 33 at predetermined intervals in the longitudinal direction. The recess 33 has an opening in the main surface 32 a of the tape body 32. A cover tape 34 is affixed to the main surface 32 a of the tape body 32, and the cover tape 34 covers the recess 33 in which the multilayer capacitor 10 is accommodated. The recess 33 is a storage portion in which the multilayer capacitor 10 is stored.

  As shown in FIG. 10C, in the multilayer capacitor 10, the first main surface 12a of the multilayer body 12 faces the cover tape 34, and the second main surface 12b of the multilayer body 12 faces the bottom surface 33a of the recess 33. It is housed in the recess 33 in a state of being opposed.

  When the multilayer capacitor 10 is housed in such a state where the directions are aligned, it is easy to mount the multilayer capacitor 10 so that audible sound is reduced. That is, when the multilayer capacitor 10 is taken out from the multilayer capacitor series 30 and mounted, the cover tape 34 is peeled off, and the first main surface 12a of the multilayer body 12 of the multilayer capacitor 10 housed in the concave portion 33 is adsorbed and laminated. The capacitor 10 is taken out from the storage unit 33. The multilayer capacitor 10 is arranged on the circuit board so that the second main surface 12b of the multilayer body 12 faces the mounting surface of the circuit board while the first main surface 12a of the multilayer body 12 is adsorbed. Can do. Thereby, the multilayer capacitor 10 can be easily mounted on the circuit board so that the audible sound is reduced.

  <Summary> The multilayer capacitor 10 described above can reduce audible sound while obtaining a high degree of freedom in circuit design.

  The present invention is not limited to the above embodiment, and can be implemented with various modifications.

DESCRIPTION OF SYMBOLS 10 Multilayer capacitor | condenser 11 Unbaked ceramic green sheet 11a 1st virtual circle 11b 2nd virtual circle 12 Laminated body 12a 1st main surface 12b 2nd main surface 12c Effective area | region 12d, 12e Peripheral area | region 12s 1st side surface 12t 2nd side surface 12m 3rd side surface 12n 4th side surface 12u, 12v 1st curved surface 12w, 12x 2nd curved surface 13 1st inner conductor 13s 1st end point 13t 1st intersection 13x 1st intersection Outermost inner conductor 14 First outer electrode 15 Second inner conductor 15s Second end point 15t Second intersection 15x Second outermost inner conductor 16 Second outer electrode 17 Conductive pattern 19 Bonding material 20 Mounting structure 22 Circuit board 22s Mounting surface 24 1st land 26 2nd land 26 External electrode 30 Multilayer capacitor connection 30x Through hole 31 Carrier -Loop 32 tape body 32a main surface 33 recess (storage portion)
34 Cover tape 50 Laminate 60 Mold unit 62 First mold (first member)
63 First sheet member (first member)
65 Second sheet member (second member)
64 Second mold 66 Third mold 72 Anechoic box 74 Sound collection microphone 76 Sound collection meter 78 Analyzer

Claims (7)

In the multilayer capacitor mounting structure in which the multilayer capacitor is mounted on the circuit board,
The circuit board has a mounting surface on which first and second lands are formed,
The multilayer capacitor includes a multilayer body and first and second external electrodes,
The stacked body has a rectangular parallelepiped shape, and the surface of the stacked body forming the rectangular parallelepiped has first and second main surfaces facing each other, first and second side surfaces facing each other, and first surfaces facing each other. 3 and a fourth side,
The laminate is
A dielectric layer in which the first and second main surfaces are stacked in a direction facing each other;
A first inner conductor disposed along a major surface of the dielectric layer and extending to the first side surface;
A second inner conductor disposed along the major surface of the dielectric layer and extending to the second side surface;
Have
The first external electrode covers the first side surface of the multilayer body and is connected to the first internal conductor;
The second external electrode covers the second side surface of the multilayer body and is connected to the second internal conductor;
In a cross section orthogonal to the first and second side surfaces of the laminate and orthogonal to the first and second main surfaces,
A first end point reaching the first side surface or the second side surface of the first outermost inner conductor closest to the first main surface of the first and second inner conductors; The distance between the first outermost inner conductor and the first imaginary straight line passing through the first outermost point closest to the first main surface and parallel to the first main surface is H1,
A second end point reaching the first side surface or the second side surface of the second outermost inner conductor closest to the second main surface of the first and second inner conductors; When the distance between the second imaginary straight line passing through the second outermost point closest to the second main surface in the second outermost inner conductor and parallel to the second main surface is H2,
Satisfies the relationship of H1> H2,
The first external electrode is fixed to the first land in a state where the second main surface of the laminated body faces the mounting surface of the circuit board, and the second external electrode is the second external electrode. A multilayer capacitor mounting structure, wherein the multilayer capacitor is fixed to a land. The multilayer body of the multilayer capacitor includes a curved surface that connects the first and second main surfaces and the first and second side surfaces;
In the cross section of the laminate,
The radius of curvature of the first imaginary circle passing through the center and three points at both ends of the curved surface closest to the first end point is R1,
When the radius of curvature of the second imaginary circle passing through the three points at both ends and the center of the curved surface closest to the second end point is R2,
R1> R2 and
2. The multilayer capacitor mounting structure according to claim 1, wherein the second outermost inner conductor is included in a region of the second virtual circle. A tape body in which a storage portion is formed;
A cover tape that is affixed to the tape body and covers the storage portion;
A multilayer capacitor stored in the storage unit;
In a multilayer capacitor series with
The multilayer capacitor includes a multilayer body and first and second external electrodes,
The stacked body has a rectangular parallelepiped shape, and the surface of the stacked body forming the rectangular parallelepiped has first and second main surfaces facing each other, first and second side surfaces facing each other, and first surfaces facing each other. 3 and a fourth side,
The laminate is
A dielectric layer in which the first and second main surfaces are stacked in a direction facing each other;
A first inner conductor disposed along a major surface of the dielectric layer and extending to the first side surface;
A second inner conductor disposed along the major surface of the dielectric layer and extending to the second side surface;
Have
The first external electrode covers the first side surface of the multilayer body and is connected to the first internal conductor;
The second external electrode covers the second side surface of the multilayer body and is connected to the second internal conductor;
In a cross section orthogonal to the first and second side surfaces of the laminate and orthogonal to the first and second main surfaces,
A first end point reaching the first side surface or the second side surface of the first outermost inner conductor closest to the first main surface of the first and second inner conductors; The distance between the first outermost inner conductor and the first imaginary straight line passing through the first outermost point closest to the first main surface and parallel to the first main surface is H1,
A second end point reaching the first side surface or the second side surface of the second outermost inner conductor closest to the second main surface of the first and second inner conductors; When the distance between the second imaginary straight line passing through the second outermost point closest to the second main surface in the second outermost inner conductor and parallel to the second main surface is H2,
Satisfies the relationship of H1> H2,
The multilayer capacitor is stored in the storage portion in a state where the first main surface of the multilayer body faces the cover tape. The multilayer body of the multilayer capacitor includes a curved surface that connects the first and second main surfaces and the first and second side surfaces;
In the cross section of the laminate,
The radius of curvature of the first imaginary circle passing through the center and three points at both ends of the curved surface closest to the first end point is R1,
When the radius of curvature of the second imaginary circle passing through the three points at both ends and the center of the curved surface closest to the second end point is R2,
R1> R2 and
4. The multilayer capacitor string according to claim 3, wherein the second outermost internal conductor is included in a region of the second virtual circle. 5. A first step of laminating an unfired ceramic green sheet and a conductive pattern to form a mother laminate;
A first member is disposed on one side of the mother laminate in the laminating direction, a second member is disposed on the other side of the mother laminate in the laminating direction, and between the first and second members A second step of pressing the mother laminate in the laminating direction by sandwiching the mother laminate in contact with the mother laminate;
Cutting the pressed mother laminate to produce individual laminates; and
With
In the second step,
By differentiating the elasticity of the first member and the second member,
The surface of the effective region where both the first and second conductive patterns overlap from the surface of the peripheral region where only one of the first and second conductive patterns is disposed when seen through in the stacking direction The method of manufacturing a multilayer capacitor, wherein the step in the stacking direction is different on one side and the other side of the stack in the stacking direction.   The method for manufacturing a multilayer capacitor according to claim 5, wherein in the second step, the first member is a resin film, and the second member is a mold. In a multilayer capacitor comprising a multilayer body and first and second external electrodes,
The stacked body has a rectangular parallelepiped shape, and the surface of the stacked body forming the rectangular parallelepiped has first and second main surfaces facing each other, first and second side surfaces facing each other, and first surfaces facing each other. 3 and a fourth side,
The laminate is
A dielectric layer in which the first and second main surfaces are stacked in a direction facing each other;
A first inner conductor disposed along a major surface of the dielectric layer and extending to the first side surface;
A second inner conductor disposed along the major surface of the dielectric layer and extending to the second side surface;
Have
The first external electrode covers the first side surface of the multilayer body and is connected to the first internal conductor;
The second external electrode covers the second side surface of the multilayer body and is connected to the second internal conductor;
In a cross section orthogonal to the first and second side surfaces of the laminate and orthogonal to the first and second main surfaces,
A first end point reaching the first side surface or the second side surface of the first outermost inner conductor closest to the first main surface of the first and second inner conductors; The distance between the first outermost inner conductor and the first imaginary straight line passing through the first outermost point closest to the first main surface and parallel to the first main surface is H1,
A second end point reaching the first side surface or the second side surface of the second outermost inner conductor closest to the second main surface of the first and second inner conductors; When the distance between the second imaginary straight line passing through the second outermost point closest to the second main surface in the second outermost inner conductor and parallel to the second main surface is H2,
A multilayer capacitor satisfying a relationship of H1> H2.

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