JP4185452B2 - Multilayer electronic components - Google Patents

Description

The present invention relates to a multilayer electronic component such as a chip inductor.

  An example of the multilayer electronic component is a chip inductor used in a mobile phone or the like. In general, a multilayer chip inductor has a laminate in which an insulating sheet and a plurality of conductor patterns constituting a coiled conductor are laminated, and each conductor pattern is connected to each other through a via hole formed in the insulating sheet. (For example, refer to Patent Document 1). Among the conductor patterns, the conductor patterns located on both ends of the coiled conductor and corresponding to the input / output ends are formed so as to be drawn to the edge of the insulating sheet. And this conductor pattern is connected to the terminal electrode which consists of silver etc. formed in the end surface of the laminated body by which an insulating sheet is laminated | stacked in the part pulled out to the edge of the insulating sheet. A plating film is formed on the surface of the terminal electrode by electroplating or the like.

In manufacturing such a multilayer chip inductor, in general, firing is performed after laminating an insulating sheet and a conductor pattern. The completed multilayer chip inductor is usually mounted on the circuit board by being reflowed at a melting temperature of solder of about 183 ° C. or higher. That is, a multilayer chip inductor is mounted on a solder printed with a metal mask or the like on a circuit board, and then the multilayer chip inductor is fixed on the circuit board by heating.
JP 2003-109820 A

  7 to 9 are diagrams showing conventional multilayer chip inductors 50 including those described in Patent Document 1. In FIG. In the multilayer chip inductor 50, the conductor pattern 52 of the multilayer body 51 and the insulating portion 53 made of an insulating sheet contract due to heating during firing. At this time, since the contraction ratio of the conductor pattern 52 is larger than the contraction ratio of the insulating portion 53, a gap 54 is generated between the conductor pattern 52 and the insulating portion 53 as shown in FIG. Then, when the terminal electrode 55 is subsequently formed on the end surface of the multilayer body 51, there is a possibility that a through hole 56 connected to the gap 54 is formed in the terminal electrode 55. If the terminal electrode 55 is subjected to electroplating in this state, the surface of the terminal electrode 55 is shielded by the plating film 57 while moisture remains in the gap 54 or the through hole 56.

  When such a multilayer chip inductor 50 is fixed (mounted) on the circuit board 58 (strictly, on the land 59 of the circuit board 58) by reflow as shown in FIG. The water staying in the holes 56 is vaporized and thermally expanded by heating during reflow. When the accumulated moisture is thermally expanded, the internal pressure of the gap 54 and the through hole 56 is increased, and as shown in FIG. 8B, the plating film 57 and the solder 60 are destroyed, and the vaporized moisture is destroyed. The film 57 and part of the solder 60 are ejected to the outside of the terminal electrode 55. Then, the multilayer chip inductor 50 is displaced from a desired fixed position on the circuit board 58 as shown in FIG. 9A due to the reaction of the jet output of vaporized water or the like, or as shown in FIG. 9B. Therefore, the circuit board 58 may be raised and may not be mounted on the circuit board 58 with high accuracy. Further, when the vaporized water is ejected to the outside of the terminal electrode 55, the molten solder 60 may be scattered at the same time and reach the terminals of nearby electrical components. When the solder 60 that reaches the terminal of the electrical component is rapidly cooled, a short circuit is caused and the circuit operation is disabled. Therefore, the conventional multilayer chip inductor 50 has not been sufficiently reliable.

  In recent years, lead-free solder is frequently used as reflow solder. However, since lead-free solder has a high melting temperature, it is necessary to increase the reflow temperature, and the above-described disadvantages of the prior art appear more remarkably. . Such a problem may occur not only in chip inductors but also in multilayer electronic components such as chip beads and LC components. Therefore, there is a need for a more reliable multilayer electronic component at present.

The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide a highly reliable multilayer electronic component that can prevent solder from being scattered in a reflow process when mounted on a circuit board. To do.

The multilayer electronic component of the present invention includes a main body formed of an insulating material, a coiled conductor formed inside the main body, and a pair of end faces of the main body, each end of the coiled conductor. A pair of terminal electrodes connected to each other, and a plating film covering the surface of the terminal electrode, and the thickness of the terminal electrode is the thickest at the central part, and becomes thinner from the central part toward the edge, and the coil shape The end portion of the conductor is located at substantially the center in the width direction of the end surface, the length in the width direction of the end portion is larger than the length in the width direction in the other part of the coiled conductor, and the terminal electrode The end portion is not more than ½ of the length in the width direction of the end face so that the end portion is not positioned on the edge side . In addition, “insulating material” in this specification refers to an insulating magnetic material such as a nonmagnetic material or ferrite.

For example, the thickness of the terminal electrode of a multilayer electronic component such as a multilayer chip inductor is the thickest in the center in manufacturing, and becomes thinner from the center toward the edge. In the multilayer electronic component of the present invention, the end portion of the coiled conductor connected to the terminal electrode is located in the center portion of the terminal electrode having a large film thickness, and the width direction of the end surface on which the terminal electrode is formed in the main body portion Since the length is ½ or less of the length, the end portion is not positioned on the edge side of the terminal electrode where the film thickness becomes extremely thin, and there is a slight gap between the end portion and the main body portion. Even if it occurs, it is possible to prevent the generation of through holes in the terminal electrode. Therefore, it is possible to reduce the possibility of the solder scattering in the reflow process. Moreover, the length of the width direction of an edge part is larger than the length of the width direction in the other site | part of a coil-shaped conductor. Thereby, an increase in DC resistance of the coiled conductor can be prevented.

The coiled conductor is formed by firing a conductor paste, and the metal content of the conductor paste forming the end of the coiled conductor is 86.0 to 93.0% by weight, and the ends are spaced apart from each other. In the region defined by the inner wall surface of the main body part surrounding the part, the ratio of the cross-sectional area occupied by the end part is preferably 80% or more.

The metal content of the conductor paste that forms the end of the coiled conductor is 86.0 to 93.0% by weight, so that after firing, the inner wall surface of the main body that surrounds the end with a gap therebetween In the region to be defined, the cross-sectional area ratio occupied by the end portion can be 80% or more. Thus, in the region defined by the inner wall surface of the main body part that surrounds the end part with a gap therebetween, the ratio of the cross-sectional area occupied by the end part is 80% or more. The gap with the inner wall surface of the portion can be reduced, and the possibility that a through hole is generated in the terminal electrode can be further reduced. Therefore, it is possible to reduce the possibility of the solder scattering in the reflow process.

The plating film preferably has a Cu layer having a thickness of 2.2 μm or more, a Ni layer having a thickness of 1.5 μm or more, and a Sn layer having a thickness of 3.0 μm or more. Alternatively, the plating film preferably has a Ni layer having a thickness of 3.2 μm or more and a Sn layer having a thickness of 3.0 μm or more.

  Thus, a plating film having a Cu layer thickness of 2.2 μm or more, a Ni layer thickness of 1.5 μm or more, and a Sn layer thickness of 3.0 μm or more, or a Ni layer thickness of 3.2 μm or more, By shielding the terminal electrode with a plating film having a Sn layer thickness of 3.0 μm or more, the through-hole is reliably shielded even if a slight through-hole is formed in the terminal electrode. The ejection of water vaporized in the process can be prevented. Therefore, it is possible to reduce the possibility of the solder scattering in the reflow process.

  In the plated film having the Cu layer, the Ni layer, and the Sn layer, the Cu layer has a thickness of 8.0 μm or less, the Ni layer has a thickness of 4.0 μm or less, and the Sn layer has a thickness of 8.0 μm or less. In the plated film having a layer, the thickness of the Ni layer is preferably 7.0 μm or less, and the thickness of the Sn layer is preferably 8.0 μm or less. As a result, the manufacturing cost can be suppressed, and it is possible to prevent the multilayer electronic component from becoming large and having different sizes.

  ADVANTAGE OF THE INVENTION According to this invention, the highly reliable multilayer electronic component which can prevent scattering of solder in the reflow process at the time of mounting on a circuit board is realizable.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals, and redundant description is omitted. In the present embodiment, a multilayer chip inductor will be described as an example of a multilayer electronic component.

  FIG. 1 is a perspective view showing a multilayer chip inductor (hereinafter abbreviated as inductor) according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the inductor shown in FIG. The inductor 1 includes a rectangular parallelepiped main body 2 formed of an insulating material, and a pair of external electrodes 3 and 3 formed on a pair of end faces in the longitudinal direction of the main body 2. The external electrodes 3 and 3 are composed of a terminal electrode 10 mainly composed of silver and a plating film 11 formed so as to cover the surface of the terminal electrode 10 and made of Cu, Ni and Sn, or Ni and Sn. Has been.

  A coiled conductor 5 is formed inside the main body 2. As will be described in detail later, the main body 2 is a laminate in which conductor patterns 6 and magnetic green sheets 7 constituting the coiled conductor 5 are alternately laminated in the direction of the arrow Z shown in FIGS. It is formed by firing. As shown in FIG. 2, the end portions 5 a and 5 b of the coiled conductor 5 are drawn to the edge of the main body 2 and are connected to the terminal electrodes 10 and 10, respectively. In addition, although this embodiment demonstrates the case where the main-body part 2 is formed from a magnetic material as an insulating material, the main-body part 2 may be formed from the nonmagnetic material as an insulating material.

  FIG. 3 is a cross-sectional view of the inductor 1 shown in FIG. 1 taken along the line III-III and shows an end face of the main body 2. FIG. 4 is a schematic view of the inductor 1 shown in FIG. 3 taken along the line IV-IV. 3 and 4 show the end portion 5b side of the inductor 1, the end portion 5a has the same configuration as the end portion 5b, and hence is hereinafter referred to as the end portions 5b and 5a. Give an explanation.

As shown in FIG. 4, the end portions 5b and 5a are portions expanded in the width direction (X direction) substantially orthogonal to the laminating direction (Z direction) of the conductor pattern 6 described later, as shown in FIG. Furthermore, it is located at the approximate center of the main body 2 in the width direction. Further, the length L ₁ in the width direction of the end portion 5 b is equal to or less than ½ of the length L ₂ in the width direction of the main body portion 2.

  FIG. 5 is an enlarged view of region A shown in FIG. The conductor pattern 6 is surrounded by an inner wall surface of the main body portion 2 with a gap therebetween, but the end portions 5b and 5a which are part of the conductor pattern 6 are similarly surrounded by the inner wall surface of the main body portion 2 with a gap therebetween. It is. And in the area | region 4a defined by the inner wall face of the main-body part 2, the cross-sectional area ratio which the edge parts 5b and 5a occupy is 80% or more.

  FIG. 6 is a diagram illustrating a stacked state during manufacturing. As shown in FIG. 6, in the main body 2, conductor patterns 6 constituting the coiled conductor 5 and magnetic green sheets 7 are alternately laminated, and further, conductor patterns 6 are formed above and below in the lamination direction. A plurality of magnetic green sheets 8 that are not formed are laminated.

  As the magnetic green sheets 7 and 8, for example, those formed by binding magnetic powder such as ferrite powder with a binder into a sheet shape are used. The thickness of the magnetic green sheets 7 and 8 is, for example, about 20 μm.

  For the formation of the conductor pattern 6, for example, a conductor paste formed by kneading silver powder with a binder is used. The conductor pattern 6 is formed on the magnetic green sheet 7 so as to be connected to each other in a coil shape when laminated together with the magnetic green sheet 7. In the main body 2 according to the present embodiment, the conductor pattern 6 including the ends 5a and 5b of the coiled conductor 5 is substantially parallel to the side connecting the pair of terminal electrodes 10 and 10 of the magnetic green sheet 7, Further, the magnetic green sheet 7 is drawn to the edge and exposed to the end face of the magnetic green sheet 7. Further, the other conductor pattern 6 is formed with 1/2 turn of the coiled conductor 5 with respect to each magnetic green sheet 7. As described above, the end portions 5a and 5b are located at substantially the center in the width direction of the magnetic green sheet 7 (the width direction of the main body portion 2), and the length in the width direction is the other length of the coiled conductor 5. It is formed so as to be larger than the portion and ½ or less of the length of the magnetic green sheet 7 in the width direction.

  The conductor patterns 6 formed on the plurality of magnetic green sheets 7 as described above are connected to each other through through holes 9 formed in the magnetic green sheets 7 to form a coil shape. The coiled conductor 5 is configured. In addition, the conductor pattern 6 positioned at the end portions 5a and 5b of the coiled conductor 5 is connected to the terminal electrodes 10 and 10 at the edge of the magnetic green sheet 7 (see FIG. 2).

  Next, a method for manufacturing the inductor 1 will be described.

  First, using a magnetic material such as Ni—Cu—Zn based ferrite, Ni—Cu—Zn—Mg based ferrite, or Ni—Cu based ferrite, a plurality of magnetic green sheets 7 and 8 are prepared by a known method.

  Next, a through hole 9 is formed at a predetermined position of the magnetic green sheet 7 by laser processing or the like. Then, using the above-described conductor paste, a conductor pattern (conductive layer) 6 is formed on the magnetic green sheet (insulating layer) 7 by screen printing, for example, and then dried. When printing the conductor paste, as described above, the end portions 5a and 5b of the coiled conductor 5 are larger in the center in the width direction of the magnetic green sheet 7 than the length in the width direction in other parts, and It forms so that it may become 1/2 or less of the length of the width direction of the magnetic body green sheet 7. FIG. The conductor paste is formed by kneading silver powder with a binder, and the metal content of the conductor paste used for the end portions 5a and 5b is 86.0 to 93.0% by weight. The general metal content of the conductor paste is 74.0 to 82.0% by weight, but the inner wall surface of the main body 2 can be reduced while suppressing the manufacturing cost by setting it to 86.0 to 93.0% by weight. In the region 4a defined by the above, the cross-sectional area occupied by the end portions 5a and 5b can be 80% or more. In order to improve the balance between the manufacturing cost and the characteristics of the end portions 5a and 5b, the metal content of the conductor paste used for the end portions 5a and 5b is 88.0 to 91.0% by weight. It is desirable to do.

Next, the magnetic green sheet 8 and the magnetic green sheet 7 with the conductor pattern 6 are laminated and pressure-bonded. In this case, first, a plurality of magnetic green sheets 8 are laminated, a plurality of magnetic green sheets 7 with a conductor pattern 6 are laminated on the magnetic green sheets 8, and a magnetic body with the conductor patterns 6 is further laminated. A plurality of magnetic green sheets 8 are laminated on the green sheet 7. Thereby, the conductor pattern 6 on the magnetic green sheet 7 is protected. In addition, it is preferable that the pressure applied in the case of pressure bonding shall be about 650-1000 kg / cm < ² >, for example.

  The through hole 9 of the magnetic green sheet 7 is formed in a portion where the ends of the adjacent conductor patterns 6 overlap each other, and the conductive pattern 6 is spirally formed through the through hole 9 by stacking the magnetic green sheets 7. Connected.

  Usually, at the stage where these magnetic green sheets 7 and 8 are laminated, a wafer is formed in which a plurality of coiled conductors 5 are arranged. By cutting the wafer into a predetermined shape and size, A plurality of unfired laminated bodies each containing one coiled conductor 5 are obtained. Thereafter, the laminate is fired at a predetermined temperature to obtain the main body 2.

  The main body 2 is generally a rectangular parallelepiped so that the position where the external electrodes 3 and 3 are formed is easy to specify. For example, after firing, the length in the longitudinal direction is 1.6 mm, and the width and height are about 0.8 mm. It cuts so that it may become. In this case, the end portions 5 a and 5 b of the coiled conductor 5 are cut so as to be located on the end surface in the longitudinal direction of the main body portion 2. The firing temperature is, for example, about 870 ° C.

  Next, the terminal electrodes 10 and 10 are formed by applying and baking a conductor paste mainly composed of silver on the end face of the main body 2 where the ends 5a and 5b of the coiled conductor 5 are exposed. Then, electroplating is performed on the surfaces of the terminal electrodes 10, 10 to form plated films 11, 11, which are external electrodes 3, 3. At this time, the plating films 11 and 11 are formed using Cu, Ni and Sn, or Ni and Sn. At that time, when Cu, Ni and Sn are used, the thickness of the Cu layer is 2.2 μm or more, the thickness of the Ni layer is 1.5 μm or more, the thickness of the Sn layer is 3.0 μm or more, and Ni and Sn are used. In this case, the plating film is formed with a Ni layer thickness of 3.2 μm or more and a Sn layer thickness of 3.0 μm or more. Thus, the inductor 1 according to this embodiment is completed.

  In the inductor 1 according to this embodiment, the end portions 5a and 5b of the coiled conductor 5 are not more than ½ of the length in the width direction of the main body portion 2 at the thick central portion of the terminal electrodes 10 and 10. By being formed, the end portions 5a and 5b are not positioned on the edge side of the terminal electrodes 10 and 10 where the film thickness becomes extremely small. Therefore, even when a slight gap is generated between the end portions 5a and 5b and the inner wall surface of the main body 2, it is possible to prevent the generation of the through-holes 56 connected to the gap as shown in FIG. it can.

  Further, since the cross-sectional area ratio occupied by the end portions 5b and 5a in the region 4a of the main body 2 is 80% or more, the gap between the conductor pattern 6 and the main body 2 can be suppressed. The possibility that through holes are generated in the terminal electrodes 10 and 10 is reduced.

  When the plating films 11 and 11 are made of Cu, Ni, and Sn, the Cu layer is formed with a thickness of 2.2 μm or more, the Ni layer is formed with a thickness of 1.5 μm or more, and the Sn layer is formed with a thickness of 3.0 μm or more. In the case of consisting of Sn, the Ni layer is formed with a thickness of 3.2 μm or more, and the Sn layer is formed with a thickness of 3.0 μm or more, so that even though some through holes are formed in the terminal electrodes 10, 10, Therefore, it is possible to prevent the water vaporized in the reflow process from being ejected.

  Therefore, the inductor 1 according to the present embodiment is provided with a plurality of characteristic configurations as described above, so that the problem to be solved by the present invention, that is, the scattering of solder in the reflow process when mounted on the circuit board. Can be reliably prevented. Thereby, it can mount in a favorable state on a circuit board, and can be made extremely excellent in reliability.

  Further, in the inductor 1 according to the present embodiment, the lengths in the width direction of the end portions 5 a and 5 b are larger than the lengths in the width direction at other portions of the coiled conductor 5. For this reason, it is possible to prevent the DC resistance of the coiled conductor 5 from increasing and to improve the electrical characteristics.

  In addition, when forming the plating films 11 and 11 using Cu, Ni, and Sn, in order to shield the said through-hole more firmly, the thickness of Cu layer is 2.5 micrometers or more, and the thickness of Ni layer is used. It is desirable that the thickness is 2.0 μm or more and the thickness of the Sn layer is 3.0 μm or more.

  When the plating films 11 and 11 are formed using Cu, Ni, and Sn, the thickness of the Cu layer is 8.0 μm or less, the thickness of the Ni layer is 4.0 μm or less, and the thickness of the Sn layer is 8.0 μm. When formed using Ni and Sn, the thickness of the Ni layer is preferably 7.0 μm or less and the thickness of the Sn layer is preferably 8.0 μm or less. As a result, the manufacturing cost can be suppressed, and the inductor 1 can be prevented from becoming large and having different sizes.

  The preferred embodiment of the present invention has been described in detail above, but the present invention is not limited to the above embodiment. For example, a terminal electrode conductor paste mainly composed of silver is applied to the end face of the laminate before firing, which is composed of the conductor pattern 6 and the magnetic green sheets 7 and 8, and the laminate is then used as the terminal electrode conductor paste. At the same time, it may be fired at a predetermined temperature. Further, instead of the sheet lamination method as in the above embodiment, a printing method in which insulating layers and conductor layers are alternately printed and laminated may be used. Furthermore, the present invention is not limited to an inductor as a multilayer electronic component, and the same effect can be obtained when applied to an LC component having both an inductor and a capacitor, chip beads, and the like.

Hereinafter, examples of the multilayer electronic component according to the present invention will be described in detail with reference to Tables 1 to 10. In addition, this invention is not limited to these Examples at all.
(Example 1)

  First, according to the manufacturing method described above as Example 1, a multilayer chip inductor as a multilayer electronic component according to the present invention was manufactured. Hereinafter, the manufacturing process will be described in detail with specific numerical values.

  First, a magnetic green sheet mainly composed of Ni—Cu—Zn ferrite was prepared. And the conductor paste which has silver as a main component was screen-printed on the surface of this magnetic body green sheet. At this time, the end of the coiled paste was formed in the approximate center of the magnetic green sheet.

  When the conductive paste is fired as described later, it becomes a conductive pattern constituting a coiled conductor. In the conductor pattern after firing, the pattern width (the length in the X direction in FIG. 2) is about 150 μm, the thickness (the length in the Z direction in FIG. 2) is about 20 μm, and the inner diameter of the pattern (the length in the Y direction in FIG. 2). In addition, the metal content of the conductor paste forming the end of the coiled conductor was 88% by weight, and the metal content of other parts of the coiled conductor was 81% by weight. It was.

  On the other hand, the magnetic green sheet was designed so that the thickness in the stacking direction (the length in the Z direction in FIG. 2) of the above-mentioned region (region 4a shown in FIG. 5) after firing was about 30 μm.

  Such magnetic green sheets were laminated to form a wafer in which a plurality of coiled conductors were arranged. Then, it cut | disconnected by the dicer to length 1.6mm of a longitudinal direction, width and height 0.8mm, and obtained the some unbaking laminated body in which the coil-shaped conductor was each incorporated. Thereafter, barrel polishing was applied to the edge portion of the laminate. And it baked at about 870 degreeC in air | atmosphere, and obtained the main-body part of the multilayer chip inductor. The width of the end of the coiled conductor (the length in the X direction in FIG. 3) is 0.27 mm, which is equal to or less than ½ of the width of the main body 0.75 mm after firing. Designed.

  Next, a conductive paste mainly composed of silver was applied to a pair of end faces of the main body, and then baked at about 700 ° C. to form a pair of end electrodes. Thereafter, electroplating with Cu, Ni and Sn was performed to form a plating film covering each terminal electrode.

  A large number of multilayer chip inductors were manufactured as described above. As a result of examining the thickness of the Cu layer, the Ni layer and the Sn layer in the plating film by sampling, the Cu layer was 2.9 to 4.4 μm, the Ni layer was 1.7 to 2.2 μm, Sn The layer was 4.1-5.6 μm.

  Then, using these plural chip inductors, a reflow experiment was carried out with a profile at a peak temperature of 250 ° C., and the number of the soldered solders in the terminal electrode was examined. As a result, even if an experiment was conducted on 40000 pieces, 0 pieces were found to cause solder scattering.

Example 1 described above is a multilayer chip that satisfies all the three conditions of the formation position and width at the end of the coiled conductor, the metal content at the end of the coiled conductor, and the thickness of each layer of the plating film. It is an experimental result about an inductor. Then, next, with reference to Tables 1-10, the experimental result about Examples 2-11 which changed the said 3 conditions is demonstrated.
(Example 2)

  Table 1 shows that the metal content at the end of the coiled conductor is 74 to 82% by weight in the same manner as in the conventional product, and the thickness of each layer of the plating film is the same as that in the conventional product, using the same manufacturing method as in Example 1 above. Similarly, in a multilayer chip inductor manufactured with a Cu layer thickness of 0.8 to 2.2 μm, a Ni layer thickness of 0.5 to 1.8 μm, and a Sn layer thickness of 4.1 to 5.6 μm, the end of the coiled conductor The number of scattered solder in the reflow experiment when the length of the width is changed is shown.

In Example 2, the experiment was performed on five types of samples (sample Nos. ₁ to 5) having different widths L1 of the end portions of the coiled conductors. Then, 6000 experiments were performed on each sample, and the number of solder splashes was examined. The width _{L 2} of the main body are the same as in the above embodiment 0.75 mm.

In Table 1, sample no. 1 has the width (0.51 mm) of the conventional product. The widths 2 to 5 are shorter than the conventional products. As shown in Table 1, sample no. 1 has a ratio (L ₁ / L ₂ ) to the width L ₂ of the main body portion of about 2/3, and the number of solder scattering was 46 out of 6000. On the other hand, Sample No. with a ratio (L ₁ / L ₂ ) to the width L _{2 of the} main body portion being 1/2 or less. 2-5, sample no. Compared to 1, it was confirmed that the number of solder splashes was greatly reduced.
( Reference example )

  Table 2 shows that the width of the end of the coiled conductor is the same as that of the conventional product (0.75 mm) by the same manufacturing method as in Example 1, and the thickness of each layer of the plating film is also the same as that of the conventional product. In the multilayer chip inductor manufactured in the same manner, the number of scattered solder in a reflow experiment when the metal content (% by weight) at the end of the coiled conductor is changed is shown.

In this reference example , an experiment was performed on eight types of samples (sample Nos. 6 to 13) having different metal contents at the ends of the coiled conductor. Then, 6000 experiments were performed on each sample, and the number of solder splashes was examined.

In Table 2, sample no. No. 6 has the same metal content (80% by weight) as the conventional product. The metal content of 7 to 13 is higher than that of the conventional product. As shown in Table 2, Sample No. with a metal content of 86% by weight or more was used. Samples Nos. 9 to 13 have a metal content of less than 86% by weight. Compared to 6-8, it was confirmed that the number of solder splashes significantly decreased.
( Reference example )

  Table 3 shows that the width of the end of the coiled conductor is the same as that of the conventional product and the metal content of the end of the coiled conductor is the same as that of the conventional product by the same manufacturing method as in Example 1 above. In the multilayer chip inductor manufactured as described above, the number of scattered solder in the reflow experiment when the Cu layer thickness and the Ni layer thickness of the plating film are changed is shown. In the plating film, the Sn layer thickness was 4.1 to 5.6 μm.

In this reference example , an experiment was performed on nine types of samples (sample Nos. 14 to 22) having different Cu layers and Ni layers of the plating film. Then, 6000 experiments were performed on each sample, and the number of solder splashes was examined.

In Table 3, sample no. No. 14 has the same Cu film thickness and Ni layer thickness of the plating film as the conventional product. The Cu layer and the Ni layer of the plating film in 15 to 22 are more than the thickness of the conventional product. As shown in Table 3, the sample Nos. Having a Cu layer thickness of 2.2 μm or more and a Ni layer thickness of 1.5 μm or more. 18 to 22 are sample Nos. Compared to 14-17, it was confirmed that the number of solder scattering greatly decreased.
( Reference example )

  Table 4 shows that the width of the end of the coiled conductor is the same as that of the conventional product by the same manufacturing method as in Example 1, and the metal content of the end of the coiled conductor is the same as that of the conventional product. In the manufactured multilayer chip inductor, the number of scattered solder in the reflow experiment when the Ni layer thickness of the plating film is changed is shown. In the multilayer chip inductor of Example 5, the plating film was composed of two layers of the Ni layer and the Sn layer, and the Sn layer thickness was 4.1 to 5.6 μm.

In this reference example , an experiment was performed on seven types of samples (sample Nos. 23 to 29) having different Ni layers of the plating film. Then, 6000 experiments were performed on each sample, and the number of solder splashes was examined.

In Table 4, sample no. No. 25 has a Ni layer thickness of the plating film similar to the conventional product. As shown in Table 3, as shown in Table 4, a sample No. having a Ni layer thickness of 3.2 μm or more was used. 26-29 are sample Nos. Compared to 23 to 25, it was confirmed that the number of solder scattering greatly decreased.
(Example 6)

  Table 5 shows that the thickness of each layer of the plating film is the same as that of the conventional product by the same manufacturing method as in Example 1, and the width of the end portion of the coiled conductor is good in Example 2 above. In the multilayer chip inductor manufactured as 0.24 mm, the number of scattered solder in the reflow experiment when the metal content (% by weight) at the end of the coiled conductor is changed is shown.

  In Example 6, eight types of samples (samples Nos. 30 to 37) having different metal contents at the ends of the coiled conductor were tested. Then, 6000 experiments were performed on each sample, and the number of solder splashes was examined.

In Table 5, sample no. 30 has the same metal content (80% by weight) as the conventional product. The metal content of 31 to 37 is higher than that of the conventional product. As shown in Table 5, Sample No. with a metal content of 86% by weight or more was used. Samples Nos. 33 to 37 have a metal content of less than 86% by weight. Compared to 30-32, it was confirmed that the number of solder splashes significantly decreased.
(Example 7)

  Table 6 shows the results obtained in Example 2 in which the metal content at the end of the coiled conductor is the same as that of the conventional product, using the same manufacturing method as in Example 1 above, and the width of the end of the coiled conductor is as in Example 2. 3 shows the number of scattered solder in a reflow experiment in the case of changing the thickness of the Cu layer and the Ni layer of the plating film in the multilayer chip inductor manufactured as 0.24 mm in which the thickness was good. In the plating film, the Sn layer thickness was 4.1 to 5.6 μm.

  In Example 7, nine types of samples (sample Nos. 38 to 46) having different Cu layers and Ni layers of the plating film were tested. Then, 6000 experiments were performed on each sample, and the number of solder splashes was examined.

In Table 6, sample no. No. 38 has the same Cu layer thickness and Ni layer thickness of the plating film as the conventional product. The Cu layer and the Ni layer of the plating film in 39 to 46 are more than the thickness of the conventional product. As shown in Table 6, a sample No. having a Cu layer thickness of 2.2 μm or more and a Ni layer thickness of 1.5 μm or more. 42 to 46 are sample Nos. Compared to 38 to 41, it was confirmed that the number of solder splashes significantly decreased.
( Reference example )

  Table 7 shows the results of Example 3 in which the end portion of the coiled conductor was made the same as the conventional product by the same manufacturing method as in Example 1, and the metal content at the end of the coiled conductor was the same as in Example 3. 3 shows the number of scattered solder in a reflow experiment in the case of changing the thickness of the Cu layer and the Ni layer of the plating film in the multilayer chip inductor manufactured with 91% by weight. In the plating film, the Sn layer thickness was 4.1 to 5.6 μm.

In this reference example , an experiment was performed on nine types of samples (sample Nos. 47 to 55) in which the Cu layer and the Ni layer of the plating film were different. Then, 6000 experiments were performed on each sample, and the number of solder splashes was examined.

In Table 7, sample no. 47 has the same Cu layer thickness and Ni layer thickness of the plating film as the conventional product. The Cu layer and the Ni layer of the plating film in 48 to 55 are not less than the thickness of the conventional product. As shown in Table 7, a sample No. having a Cu layer thickness of 2.2 μm or more and a Ni layer thickness of 1.5 μm or more. 51-55 are sample Nos. Compared to 47 to 50, it was confirmed that the number of solder splashes significantly decreased.
Example 9

Table 8 shows that the thickness of each layer of the plating film was the same as that of the conventional product by the same manufacturing method as in Example 1, and the metal content at the end of the coiled conductor was good in Example 3 above. in multilayer chip inductor was prepared as a 91 wt% shows the scattered number of solder reflow experiment of varying the length L ₁ of the width of the end portion of the coiled conductor.

In Example 9, experiments were performed on five types of samples (sample Nos. 56 to 60) having different widths at the ends of the coiled conductors. Then, 6000 experiments were performed on each sample, and the number of solder splashes was examined. The width _{L 2} of the main body are the same as in the above embodiment 0.75 mm.

In Table 8, sample no. 56 has the width (0.51 mm) of the conventional product. The widths 57-60 are shorter than the conventional products. As shown in Table 8, sample no. _No. 56 has a ratio (L ₁ / L ₂ ) to the width L ₂ of the main body portion of about 2/3, and the number of solder scattering was 19 out of 6000. On the other hand, Sample No. with a ratio (L ₁ / L ₂ ) to the width L _{2 of the} main body portion being 1/2 or less. In Samples 57-60, Sample No. Compared to 56, it was confirmed that the number of solder splashes significantly decreased.
(Example 10)

Table 9 shows that the plating layer was formed with the Cu layer thickness of 2.5 to 4.91 μm, the Ni layer thickness of 1.5 to 3.1 μm, and the Sn layer thickness of 4.1 to 5. Reflow when the length L ₁ of the end of the coiled conductor is changed in a multilayer chip inductor having a metal content of 6 μm and the end of the coiled conductor manufactured in the same manner as the conventional product. The number of scattered solder in the experiment is shown.

In Example 10, an experiment was performed on five types of samples (sample Nos. 61 to 65) having different widths at the end portions of the coiled conductor. Then, 6000 experiments were performed on each sample, and the number of solder splashes was examined. The width _{L 2} of the main body are the same as in the above embodiment 0.75 mm.

In Table 9, sample no. 61 has the width (0.51 mm) of the conventional product. The widths 62 to 65 are shorter than the conventional products. As shown in Table 9, sample no. 61 had a ratio (L ₁ / L ₂ ) to the width L ₂ of the main body portion of about 2/3, and the number of solder scattering was 21 out of 6000. On the other hand, Sample No. with a ratio (L ₁ / L ₂ ) to the width L _{2 of the} main body portion being 1/2 or less. 62-65, sample no. Compared to 61, it was confirmed that the number of solder splashes significantly decreased.
( Reference example )

  Table 10 shows that the Cu film thickness 2.5 to 4.91 μm, the Ni layer thickness 1.5 to 3.1 μm, and the Sn layer thickness 4.1 to 5. Reflow when the metal content (% by weight) at the end of the coiled conductor is changed in a multilayer chip inductor with a width of 6 μm and the width of the end of the coiled conductor manufactured in the same manner as the conventional product The number of scattered solder in the experiment is shown.

In this reference example , an experiment was performed on eight types of samples (sample Nos. 66 to 73) having different metal contents at the ends of the coiled conductor. Then, 6000 experiments were performed on each sample, and the number of solder splashes was examined.

  In Table 10, sample no. No. 66 has the same metal content (80% by weight) as the conventional product. The metal content of 67 to 73 is higher than that of the conventional product. As shown in Table 5, Sample No. with a metal content of 86% by weight or more was used. Nos. 69 to 73 are sample Nos. With a metal content of less than 86% by weight. Compared to 66-68, it was confirmed that the number of solder splashes significantly decreased.

  As mentioned above, although Examples 1-11 were demonstrated, Of three conditions of the formation position and width length in the edge part of a coiled conductor, the metal content of the edge part of a coiled conductor, and the thickness of each layer of a plating film It was confirmed that solder scattering can be reduced by satisfying at least one condition. Furthermore, it was confirmed that by satisfying all of the above three conditions, a highly reliable multilayer electronic component capable of reliably preventing solder scattering can be realized.

1 is a perspective view showing a multilayer chip inductor as a multilayer electronic component according to an embodiment of the present invention. It is sectional drawing of the multilayer chip inductor shown in FIG. FIG. 3 is a cross-sectional view of the multilayer chip inductor shown in FIG. 1 taken along the line III-III. FIG. 4 is a schematic view of a cross section taken along line IV-IV of the multilayer chip inductor shown in FIG. 3. It is an enlarged view of the area | region A shown in FIG. It is a figure which shows the lamination | stacking state at the time of manufacture of a multilayer chip inductor. It is a figure which shows the conventional multilayer chip inductor. It is a figure which shows the conventional multilayer chip inductor. It is a figure which shows the conventional multilayer chip inductor.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Multilayer chip inductor (multilayer type electronic component), 2 ... Main-body part, 3, 3 ... External electrode, 5 ... Coiled conductor, 5a, 5b ... End part, 6 ... Conductor pattern (conductive layer), 7, 8 ... magnetic green sheet (insulating layer), 10 ... terminal electrode, 11 ... plated film, 50 ... multilayer chip inductor (multilayer electronic component), 51 ... multilayer body, 52 ... conductor pattern, 53 ... insulator, 54 ... Gaps, 55 ... terminal electrodes, 56 ... through holes, 57 ... plated film, 58 ... circuit board, 60 ... solder.

Claims (5)

A main body formed of an insulating material;
A coiled conductor formed inside the main body,
A pair of terminal electrodes formed on a pair of end faces of the main body and connected to each end of the coiled conductor;
A plating film covering the surface of the terminal electrode,
The film thickness of the terminal electrode is the thickest at the central part, and thins from the central part toward the edge,
The end of the coiled conductor is located at the approximate center in the width direction of the end face,
The length in the width direction of the end portion is larger than the length in the width direction in other portions of the coiled conductor, and the end portion is not positioned on the edge side of the terminal electrode. der 1/2 or less of the length of the width direction of the end face is,
The conductor portion constituting the end portion of the coiled conductor is located in a different layer from the remaining conductor portion of the coil conductor excluding the conductor portion,
The coiled conductor is formed by firing a conductor paste,
The metal content of the conductor paste that forms the conductor portion that constitutes the end portion of the coiled conductor is 86.0 to 93.0% by weight to form the remaining conductor portion of the coil conductor. Different from the metal content of the conductor paste,
In the region defined by the inner wall surface of said main body portion at a gap surrounding the said end portion, the multilayer electronic component section area ratio occupied by the end, characterized in der Rukoto 80% or more. The plated film, and more thickness 2.2μm of Cu layer, the thickness 1.5μm and Ni layers, the multilayer electronic component according to claim 1, characterized in that it has a thickness 3.0μm or more Sn layers . 3. The multilayer electronic component according to claim 2, wherein the Cu layer has a thickness of 8.0 μm or less, the Ni layer has a thickness of 4.0 μm or less, and the Sn layer has a thickness of 8.0 μm or less. The plating film, the multilayer electronic component according to claim 1, characterized in that it has a higher thickness 3.2μm of Ni layer, and a thickness 3.0μm or more Sn layers. The multilayer electronic component according to claim 4, wherein the Ni layer has a thickness of 7.0 μm or less, and the Sn layer has a thickness of 8.0 μm or less.

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