JP2018098334A - Coil component and manufacturing method thereof, and electronic circuit having coil component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coil component in which disconnection of a wire is prevented.SOLUTION: A coil component comprises: a core having a winding core part 21 and a flange part 22; terminal electrodes 31 and 32 provided to the flange part 22; wires W1 and W2 wound to the winding core part 21, and in which an end part is connected to the terminal electrodes 31 and 32; and a protection resin 50 covering at least one part of the wires W1 and W2. Each of the wires W1 and W2, includes: a coil part C wound to the winding core part 21; a line connection part A connected to the terminal electrodes 31 and 32; and an overhead wire part B positioned between the coil part C and the line connection part A, and does not come into contact with a core 20. The protection resin 50 covers at least one part of the overhead wire part B and the line connection part A.EFFECT: Since the protection resin 50 is provided to the overhead wire part B in which line disconnection easily occurs in accordance with stress, or to the line connection part A in which peeling easily occurs in accordance with a physical impact, the stress to the coil component can be softened.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a coil component and a manufacturing method thereof, and more particularly, to a coil component that hardly breaks such as a broken wire and a manufacturing method thereof. The present invention also relates to an electronic circuit including such a coil component.

  A surface mount type coil component using a drum core is used in many electronic devices as an electronic component for noise suppression. In recent years, in order to further improve the reliability of the entire electronic circuit including the coil component, a moisture-proof coating resin may be applied to a substrate on which the coil component or the like is mounted. When the moisture-proof coating resin is applied, the electronic components mounted on the substrate are protected from moisture, so that the reliability of the entire electronic circuit is improved.

  However, as pointed out in Patent Document 1, when the moisture-proof coating resin contacts the wire of the coil component, a strong stress is applied to the wire due to a temperature change, and the wire may be disconnected in some cases.

JP 2008-159610 A

  In order to solve such a problem, Patent Document 1 proposes a method for strictly positioning a wire so that the positional relationship between the wire and the core satisfies a predetermined condition. However, in order to perform such exact positioning, a complicated and precise manufacturing process is required, so that the manufacturing efficiency is lowered and the manufacturing cost is increased. Further, the core size and the wire diameter are decreasing year by year, and it is not easy to perform such exact positioning itself.

  The wire breakage may be caused not only by the moisture-proof coating resin but also by physical impact or the like. Further, when a physical impact is applied to the coil component, there is a possibility that the connection portion between the wire and the terminal electrode may be peeled off, or the core or the top plate may be cracked or chipped.

  As described above, in the conventional coil component, sufficient countermeasures have not been taken against the stress on the coil component that may occur during or after mounting.

  Accordingly, an object of the present invention is to provide a coil component that can relieve stress on the coil component that may occur at the time of mounting or after mounting without requiring a complicated and precise manufacturing process, a manufacturing method thereof, and such a coil. To provide an electronic circuit with components.

  The coil component according to the present invention includes a core having a winding core portion and a flange portion, a terminal electrode provided on the flange portion, a wire wound around the winding core portion, and an end portion connected to the terminal electrode; A protective resin that covers at least a part of the wire, and the wire includes a coil portion wound around the core portion, a connecting portion in contact with the terminal electrode, the coil portion, and the connecting portion. The protection resin covers at least a part of the overhead wire portion and the connecting wire portion.

  According to the present invention, since the protective resin is provided on the overhead wire portion that is likely to be disconnected due to stress and the connecting portion that is likely to be peeled off due to physical impact, the protective resin may be provided during or after mounting on the substrate. The stress on the coil component can be reduced. In addition, the manufacturing process is not complicated because it is not necessary to strictly position the wires. Thereby, it becomes possible to improve the reliability of coil components, suppressing the increase in manufacturing cost.

  In this invention, it is preferable that the said protective resin covers the whole said overhead wire part so that the said overhead wire part may not be exposed. According to this, it becomes possible to prevent the disconnection in an overhead wire part more effectively.

  The coil component according to the present invention further includes a top plate connected to the flange, and the top plate has a lower surface facing the core side and an upper surface located on the opposite side of the lower surface, and the top plate It is preferable that at least a part of the lower surface is covered with the protective resin. According to this, it becomes possible to relieve the physical impact applied through the top plate. In addition, the application position of the protective resin is easily controlled by the presence of the top plate.

  In this case, the flange portion is located on the inner surface on which the core portion is provided, the outer surface located on the opposite side of the inner surface, the upper surface facing the top plate, and the opposite side of the upper surface. And the upper surface of the flange has an upper surface to which the top plate is connected, and a lower surface that is set back from the upper surface and forms a space between the top plate, The terminal electrode is continuously formed across the lower step surface, the outer surface and the lower surface of the flange portion, and the connecting portion of the terminal electrode is connected to a portion formed on the lower step surface, It is preferable that at least a part of the space is filled with the protective resin. According to this, the connecting portion of the wire is more reliably protected. In addition, since the wire is connected to the upper surface side of the collar portion on which the top plate is provided, connection failure with the substrate does not occur due to the presence of the protective resin.

  Furthermore, in this case, the protective resin may be provided on the upper surface of the top plate, between the lower surface of the top plate and the core portion, and on the outer surface of the flange portion. Thus, if it is the structure where a wire is connected to the upper surface side of a collar part, it will become possible to cover most coil components with protective resin.

  In the present invention, the Young's modulus at normal temperature of the protective resin is preferably 20000 MPa or less. According to this, it is possible to sufficiently relax the stress applied to the wire due to temperature change.

  The coil component manufacturing method according to the present invention includes a core having a winding core portion and a flange portion, a terminal electrode provided on the flange portion, a coil portion wound around the winding core portion, and the terminal electrode. Prepare a coil component including a connecting wire portion, a wire positioned between the coil portion and the connecting wire portion, including an overhead wire portion that does not contact the core, and a top plate connected to the flange portion. And a step of covering at least a part of the overhead wire portion and the connection portion of the wire with a protective resin.

  ADVANTAGE OF THE INVENTION According to this invention, the coil components by which the overhead wire part and the connection part of the wire were covered with protective resin can be manufactured easily. In addition, since the protective resin is supplied to the coil components including the top plate, the connecting surface between the collar and the top plate is not covered with the protective resin, and the presence of the top plate allows the application of the protective resin. Position control becomes easy.

  The electronic circuit according to the present invention further includes a substrate, the coil component mounted on the substrate, and a moisture-proof coating resin that covers at least a part of the wire, and the Young's modulus of the protective resin is the moisture-proof coating. It is characterized by being lower than the Young's modulus of the resin. According to this, since the stress applied from the moisture-proof coating resin to the wire due to the temperature change is relaxed by the protective resin, it is possible to prevent the wire from being disconnected.

  According to the present invention, it is possible to alleviate stress on a coil component that may occur during or after mounting on a substrate without going through a complicated and precise manufacturing process. Thereby, it becomes possible to improve the reliability of coil components.

FIG. 1 is a schematic perspective view showing an appearance of a coil component 10 according to a preferred embodiment of the present invention. FIG. 2 is an exploded perspective view of the coil component 10. FIGS. 3A and 3B are diagrams for explaining a state in the vicinity of the ends of the wires W1 and W2, where FIG. 3A is a diagram viewed from the y direction, and FIG. 3B is a diagram viewed from the z direction. FIG. 4 is a schematic cross-sectional view showing a modification of the coil component 10. FIG. 5 is a top view showing a part of the substrate 100 on which the coil component 10 is mounted. FIG. 6 is a cross-sectional view showing a part of an electronic circuit 200 in which the coil component 10 is mounted on the substrate 100.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic perspective view showing an appearance of a coil component 10 according to a preferred embodiment of the present invention. FIG. 2 is an exploded perspective view of the coil component 10.

  As shown in FIGS. 1 and 2, the coil component 10 according to the present embodiment includes a core 20 having a winding core portion 21 and flange portions 22 and 23, four terminal electrodes 31 to 34 provided on the flange portion, Two wires W <b> 1 and W <b> 2 that are wound around the core portion 21 of the core 20 and whose end portions are respectively connected to the corresponding terminal electrodes 31 to 34, and a top plate 40 that covers the core 20 are provided.

  The core 20 is an integral drum core made of a magnetic material such as ferrite, and the axial direction of the winding core 21 is the x direction. On both sides of the core part 21 in the x direction, flange parts 22 and 23 are provided, respectively. The flange portions 22 and 23 are respectively provided with inner side surfaces 22i and 23i provided with the core portion 21, outer side surfaces 22o and 23o positioned on the opposite side of the inner side surfaces 22i and 23i, and upper surfaces 22t and 23t having step shapes. The lower surfaces 22b and 23b are located opposite to the upper surfaces 22t and 23t. The inner side surfaces 22i, 23i and the outer side surfaces 22o, 23o all constitute a yz plane, and the upper surfaces 22t, 23t and the lower surfaces 22b, 23b all have an xy plane.

Upper surface 22t of the flange portion 22 includes an upper surface 22t ₁ positioned at the center of the y-direction, has a set-back two lower surface 22t ₂ from the top surface 22t _1, the upper surface 22t ₁ is lower surfaces It protrudes in the z-direction from 22t _2. Similarly, the upper surface 23t of the flange portion 23, an upper surface 23t ₁ positioned at the center of the y-direction, has two lower surface 23t ₂ which is set back from the upper surface 23t _1, the upper surface 23t ₁ protrudes from the lower surface 23t ₂ in the z direction. Upper stage surfaces 22t ₁ and 23t ₁ are surfaces to which the top plate 40 is connected.

  The top plate 40 has a lower surface 41 facing the core 20 side and an upper surface 42 located on the opposite side of the lower surface 41. Both the lower surface 41 and the upper surface 42 of the top plate 40 constitute an xy plane, and the coil component 10 can be handled by using the upper surface 42 of the top plate 40 as a suction surface when mounted on the substrate. Further, if a magnetic material is used as the material of the top plate 40, the core 20 and the top plate 40 can constitute a closed magnetic path. However, it is not essential that the top plate 40 is made of a magnetic material. The connection method of the top plate 40 is not particularly limited, and for example, an adhesive may be used.

When the top plate 40 is connected to the core 20, a space S is formed between the lower surface 41 of the top plate 40 and the lower step surfaces 22 t ₂ and 23 t ₂ of the flange portions 22 and 23. The height of the space S in the z direction is defined by the difference in height between the lower step surfaces 22t ₂ and 23t ₂ and the upper step surfaces 22t ₁ and 23t _{1 in} the z direction. As will be described later, the space S accommodates part of the terminal electrodes 31 to 34 and the ends of the wires W1 and W2.

The terminal electrodes 31 to 34 have upper portions 31t to 34t, lower portions 31b to 34b, and side portions 31s to 34s, respectively. Top 31t of the terminal electrodes 31 and 32, 32t is a portion that covers the lower surface 22t ₂ of the flange portion 22, the upper terminal electrode 33 and 34 33t, 34t is a portion covering the lower surface 23t ₂ of the flange portion 23 is there. Lower portions 31 b and 32 b of the terminal electrodes 31 and 32 are portions that cover the lower surface 22 b of the flange portion 22, and lower portions 33 b and 34 b of the terminal electrodes 33 and 34 are portions that cover the lower surface 23 b of the flange portion 23. The side portions 31 s and 32 s of the terminal electrodes 31 and 32 are portions that cover the outer surface 22 o of the flange portion 22, and the side portions 33 s and 34 s of the terminal electrodes 33 and 34 are portions that cover the outer surface 23 o of the flange portion 23. is there. Accordingly, the terminal electrodes 31 to 34 are continuously formed across the lower step surfaces 22t ₂ and 23t ₂ , the outer surfaces 22o and 23o, and the lower surfaces 22b and 23b of the flange portion 22 or 23.

  The wires W <b> 1 and W <b> 2 are coated conductive wires in which a core material such as copper is coated with an insulating coating, and are wound around the core portion 21 of the core 20 with the same number of turns. One end of the wire W1 is connected to the upper part 31t of the terminal electrode 31, and the other end of the wire W1 is connected to the upper part 33t of the terminal electrode 33. One end of the wire W2 is connected to the upper part 32t of the terminal electrode 32, and the other end of the wire W2 is connected to the upper part 34t of the terminal electrode 34. Thereby, since both ends of the wires W1 and W2 are accommodated in the space S formed between the flange portions 22 and 23 and the top plate 40, a structure in which physical impact is difficult to be applied from the outside. Yes. The wires W1 and W2 and the terminal electrodes 31 to 34 can be connected by welding or thermocompression bonding. However, the coil component 10 according to the present embodiment has an upper surface 22t opposite to the lower surfaces 22b and 23b which are mounting surfaces. Since the wires W1 and W2 are connected on the 23t side, it is not necessary to consider the interference between the substrate and the connecting portion. Therefore, it is preferable to use welding with higher connection strength.

  With such a configuration, the coil component 10 according to the present embodiment can be used as a surface mount type common mode filter.

  FIGS. 3A and 3B are diagrams for explaining a state in the vicinity of the ends of the wires W1 and W2, where FIG. 3A is a diagram viewed from the y direction, and FIG. 3B is a diagram viewed from the z direction. In consideration of the visibility of the drawings, the top plate 40 is omitted in FIGS. 3 (a) and 3 (b).

  As shown in FIG. 3, the wires W <b> 1 and W <b> 2 have three portions including a connecting portion A, an overhead wire portion B, and a coil portion C. The connecting portion A is a portion in contact with the terminal electrodes 31 to 34 and is a portion fixed to the terminal electrodes 31 to 34 by welding or thermocompression bonding. The coil part C is a part wound around the core part 21. The overhead wire portion B is a portion that is located between the connecting portion A and the coil portion C and is wired in the air without contacting the core 20. And in the coil component 10 by this embodiment, the whole overhead wire part B is covered with the protective resin 50 so that the overhead wire part B may not be exposed. Thereby, the overhead wire portion B that is most likely to be disconnected can be protected by the protective resin 50.

  Further, in the present embodiment, the protective resin 50 also enters the space S, and a part of the connecting portion A is covered with the protective resin 50 by the protective resin 50 that has entered the space S. As a result, the connecting portion A that easily peels off from the terminal electrodes 31 to 34 is protected by the protective resin 50.

  As the protective resin 50, it is preferable to use a resin material having a Young's modulus as low as possible, and it is particularly preferable that the Young's modulus at room temperature is 20000 MPa or less. If the Young's modulus at room temperature is 20000 MPa or less, even if the moisture-proof coating resin described later is applied after mounting on the substrate, the overhead wire portions of the wires W1, W2 from the moisture-proof coating resin due to temperature change This is because the stress applied to B is sufficiently relaxed, so that disconnection of the wires W1, W2 in the overhead wire portion B can be prevented. Room temperature is 25 ° C.

  As a material of the protective resin 50, an epoxy-based resin or the like can be used. After supplying the uncured protective resin 50 using a dispenser or the like, it may be thermally cured. The supply of the uncured protective resin 50 needs to be performed after the connection of the wires W1 and W2 is completed, and it is particularly preferable that the uncured protective resin 50 be performed after the connection of the top plate 40 is completed. If the protective resin 50 is supplied after the connection of the top plate 40 is completed, the protective resin 50 does not widen the gap between the core 20 and the top plate 40, and the surface tension of the lower surface 41 of the top plate 40 is increased. Thus, it is possible to suppress the spread of the protective resin 50.

  In the present invention, it is not essential for the protective resin 50 to cover the entire overhead wire portion B, and it is sufficient if it covers at least a portion of the overhead wire portion B and at least a portion of the connecting portion A. However, since the overhead wire portion B is the portion where breakage is most likely to occur, it is preferable to cover the entire overhead wire portion B with the protective resin 50.

  In addition, it is not essential that the coil component 10 according to the present invention includes the top plate 40, but if the top plate 40 is used and the protective resin 50 is applied after the top plate 40 is connected to the core 20, excessive protection is provided. Since the resin 50 stays on the lower surface 41 of the top plate 40 due to surface tension, the application position of the protective resin 50 can be easily controlled.

  Thus, the application range of the protective resin 50 is not particularly limited as long as it covers at least a part of the overhead wire part B and at least a part of the connection part A. Therefore, as shown in FIG. 4, most of the coil component 10 excluding the lower portions 31 b to 34 b of the terminal electrodes 31 to 34, that is, the upper surface 42 of the top plate 40, the lower surface 41 of the top plate 40, and the core portion 21. The outer side surfaces 22o and 23o of the flange portions 22 and 23 may be provided so as to cover them. The lower portions 31b to 34b of the terminal electrodes 31 to 34 are exposed from the protective resin 50 because the lower portions 31b to 34b of the terminal electrodes 31 to 34 are connection portions with the substrate.

  FIG. 5 is a top view showing a part of the substrate 100 on which the coil component 10 according to the present embodiment is mounted.

  As shown in FIG. 5, a mounting area 10 </ b> A for the coil component 10 is defined on the surface of the substrate 100. The mounting region 10A is provided with land patterns P1 to P4 connected to the terminal electrodes 31 to 34, respectively, and corresponding wiring patterns L1 to L4 are connected to the land patterns P1 to P4, respectively. The wiring patterns L1 and L2 constitute a pair of differential signal lines IN, and the wiring patterns L3 and L4 constitute a pair of differential signal lines OUT. If the coil component 10 is mounted in the mounting region 10A, a common mode filter is inserted between the differential signal line IN and the differential signal line OUT, so that common mode noise superimposed on the differential signal is reduced. Can be removed.

  FIG. 6 is a cross-sectional view showing a part of an electronic circuit 200 in which the coil component 10 is mounted on the substrate 100.

  As shown in FIG. 6, when the coil component 10 is mounted on the mounting region 10 </ b> A, the terminal electrodes 31 to 34 and the land patterns P <b> 1 to P <b> 4 are electrically and mechanically connected by the solder 60. Specifically, after supplying the solder 60 to the land patterns P <b> 1 to P <b> 4, the coil component 10 is mounted on the mounting region 10 </ b> A and the solder 60 is melted by reflow, whereby the coil component 10 is fixed on the substrate 100. . The coil component 10 can be handled by adsorbing the upper surface 42 of the top plate 40.

  Here, when handling the coil component 10, physical impact may be applied to various portions of the coil component 10, and in some cases, a crack or chipping may occur in a part of the coil component 10, or the wires W <b> 1 and W <b> 2 may be joined. The line part may peel off. However, in this embodiment, since the protective resin 50 is embedded in various portions of the coil component 10, particularly the space S, such physical destruction is prevented.

  After the coil component 10 is mounted on the substrate 100, a moisture-proof coating resin 70 shown in FIG. 6 is applied to the surface of the substrate 100. Thereby, since the wires W1 and W2 and the terminal electrodes 31 to 34 are covered with the moisture-proof coating resin 70, corrosion caused by moisture is less likely to occur, and the reliability of the electronic circuit 200 is improved.

  On the other hand, when the temperature change is repeated, the moisture-proof coating resin 70 expands or contracts, and stress is applied to the coil component 10. When such stress is directly applied to the overhead wire portion B of the wires W1 and W2, there is a possibility that the overhead wire portion B is disconnected. Such a problem is particularly likely to occur when the Young's modulus of the moisture-proof coat resin 70 is high. However, in this embodiment, since the overhead wire portion B of the wires W1 and W2 is covered with the protective resin 50 having a low Young's modulus, the stress applied to the overhead wire portion B is relieved, and disconnection can be prevented. it can. Therefore, in order to obtain the above effect, the protective resin 50 having a Young's modulus lower than that of the moisture-proof coating resin 70 to be used may be used.

  Further, as the material of the protective resin 50, a material having a smaller thermal expansion coefficient than that of the moisture-proof coating resin 70 is used. The peeling of the solder 60 and the top plate 40 can be prevented. That is, if the protective resin 50 having a small thermal expansion coefficient is applied to the lower part of the core part 21, the protective resin 50 is interposed in the space between the substrate 100 and the core part 21 after mounting. There is less room for the moisture-proof coating resin 70 having a large thermal expansion coefficient to enter this space. As a result, the coil component 10 is pushed up by the expansion of the moisture-proof coating resin 70 that has entered the space, and as a result, the phenomenon that separation occurs between the terminal electrodes 31 to 34 and the land patterns P1 to P4 can be prevented. it can. In addition, if the protective resin 50 having a small thermal expansion coefficient is applied to the upper part of the core part 21, the protective resin 50 is interposed in the space between the top plate 40 and the core part 21. There is less room for the moisture-proof coating resin 70 having a large thermal expansion coefficient to enter the space. Thereby, the top plate 40 is pushed up by the expansion of the moisture-proof coating resin 70 that has entered the space, and as a result, the phenomenon that the top plate 40 peels from the core 20 can be prevented.

  Thus, the electronic circuit 200 on which the coil component 10 according to the present embodiment is mounted can prevent the coil component 10 from being damaged at the time of mounting, and the overhead wire portion B by the moisture-proof coating resin 70 even after mounting. Can be prevented.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. Needless to say, it is included in the range.

  For example, in the above embodiment, the case where the coil component is a common mode filter has been described as an example. However, the subject of the present invention is not limited to this, and can be applied to other types of coil components. It is.

10 coil component 10A mounting region 20 core 21 core portion 22 the flange portion 22b, 23b lower surface 22i, 23i inner surface 22o, 23o outer surface 22t, 23t top _22t 1, 23t ₁ upper surface _22t 2, 23t ₂ lower surface 31 -34 Terminal electrodes 31b-34b Lower 31s-34s Sides 31t-34t Upper 40 Top plate 41 Lower surface 42 Upper surface 50 Protective resin 60 Solder 70 Moisture-proof coating resin 100 Substrate 200 Electronic circuit A Connecting portion B Overhead wire portion C Coil portion L1 ~ L4 Wiring pattern P1 ~ P4 Land pattern S Space W1, W2 Wire

Claims (8)

A core having a winding core portion and a flange portion;
A terminal electrode provided on the collar,
A wire wound around the core and having an end connected to the terminal electrode;
A protective resin covering at least a part of the wire,
The wire is a coil portion wound around the winding core portion, a connecting portion that is in contact with the terminal electrode, and an overhead wire portion that is located between the coil portion and the connecting portion and is not in contact with the core Including
The coil component, wherein the protective resin covers at least a part of the overhead wire portion and the connecting wire portion.   The coil component according to claim 1, wherein the protective resin covers the entire overhead wire portion so that the overhead wire portion is not exposed. Further comprising a top plate connected to the buttocks,
The top plate has a lower surface facing the core side, and an upper surface located on the opposite side of the lower surface,
The coil component according to claim 1 or 2, wherein at least a part of the lower surface of the top plate is covered with the protective resin. The flange portion includes an inner surface provided with the winding core portion, an outer surface located on the opposite side of the inner surface, an upper surface facing the top plate, and a lower surface located on the opposite side of the upper surface. Have
The upper surface of the flange has an upper surface to which the top plate is connected, and a lower step surface that is set back from the upper surface and forms a space between the top plate,
The terminal electrode is continuously formed across the lower step surface, the outer side surface and the lower surface of the flange portion, and the connecting portion of the terminal electrode is connected to a portion formed on the lower step surface,
The coil component according to claim 3, wherein at least a part of the space is filled with the protective resin.   The coil according to claim 4, wherein the protective resin is provided on the upper surface of the top plate, between the lower surface of the top plate and the core portion, and on the outer surface of the flange portion. parts.   The coil component according to any one of claims 1 to 5, wherein the protective resin has a Young's modulus at room temperature of 20000 MPa or less. A core having a core part and a collar part, a terminal electrode provided on the collar part, a coil part wound around the core part, a connecting part in contact with the terminal electrode, and the coil part and the connecting line Preparing a coil component that includes a wire including an overhead wire portion that is not in contact with the core, and a top plate that is connected to the flange portion;
And a step of covering at least a part of the overhead wire portion and the connecting wire portion of the wire with a protective resin. A substrate,
The coil component according to any one of claims 1 to 6 mounted on the substrate;
A moisture-proof coating resin covering at least a part of the wire,
An electronic circuit, wherein the Young's modulus of the protective resin is lower than the Young's modulus of the moisture-proof coating resin.

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