JP2010016217A - Surface-mounting coil component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-mounting coil component which can be improved in product strength and reliability with respect to a change in operation temperature environment and can be reduced in height. <P>SOLUTION: The surface-mounting coil component includes a drum-shaped ferrite core 14; at least one pair of external electrodes 15a and 15b which is formed on the lower surface of a lower flange 13 of the drum-shaped ferrite core 14 and is direct-mounted on the core; a winding 17 which is wound around a winding core 11 of the drum-shaped ferrite core 14 and has both end parts conduction-connected to the external electrodes 15a and 15b; and an organic filler-containing sheathing resin 18 which contains thermosetting resin and an inorganic filler and is filled in a space between an upper flange 12 and the lower flange 13 while covering the winding 17 between the upper flange 12 and the lower flange 13 of the drum-shaped ferrite core 14. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a surface mount coil component used for an electronic device or the like.

  Surface mount coil components used in electronic equipment include a drum-type ferrite core, at least a pair of core-attached external electrodes formed on the lower surface of the lower surface of the drum-type ferrite core, and a core of the drum-type ferrite core Between the upper arm and the lower arm while covering the winding between the upper arm and the lower arm of the drum type ferrite core 2. Description of the Related Art Surface mount coil components including an exterior resin filled in a space are known.

  In order to use such surface-mounted coil components for current-compatible coils (choke coils, etc.) for DC / DC power supplies in portable electronic devices such as portable telephones and digital still cameras, the desired inductor characteristics are ensured. However, there is a demand for low profile dimensions.

  By the way, portable electronic devices are often carried around and used, and the temperature environment of use is drastically changed. For this reason, it is desirable that the surface mount coil component mounted on the component mounting board accommodated in the portable electronic device has high reliability against changes in the operating temperature environment.

  However, since the exterior resin expands and contracts with changes in the operating temperature environment, stress is applied to the ridges of the drum type ferrite core due to the expansion and contraction. For this reason, especially when the external dimensions of the surface-mounted coil component are made low, the strength of the flange of the drum-type ferrite core cannot resist the stress, and cracks may occur in the portion of the flange.

In order to improve the reliability of the surface mount coil component with respect to changes in the operating temperature environment, for example, in Patent Document 1 below, the space between the upper and lower drums of the drum type ferrite core has a physical property at the time of curing. A surface mount coil component filled with a magnetic powder-containing exterior resin having a glass transition temperature of −20 ° C. or lower in the process of transition from a glass state to a rubber state in a change in rigidity is disclosed.
Japanese Patent Laid-Open No. 2005-210055

  A resin having a glass transition temperature of −20 ° C. or lower generally has a high Young's modulus and is excellent in cushioning properties. Therefore, even if the exterior resin expands as the operating temperature environment changes, the stress applied to the chin region is reduced. For this reason, the glass transition temperature in the process of changing from the glass state to the rubber state in the change in the rigidity with respect to the temperature as a physical property at the time of curing is −20 in the space region sandwiched between the upper and lower shells of the drum type ferrite core. The surface-mounted coil component of Patent Document 1 filled with an exterior resin at a temperature of 0 ° C. or less can prevent the occurrence of cracks in the heat cycle test and has high reliability against changes in the operating temperature environment.

  However, since the exterior resin is rich in cushioning properties, it is deformed when external stress such as impact is applied to the jaw part of the drum type ferrite core, and the strength of the heel cannot be countered by the external stress. In some cases, cracks occurred in these parts.

  Accordingly, an object of the present invention is to provide a surface mount coil component that is highly reliable with respect to changes in product strength and operating temperature environment and can be reduced in height.

In achieving the above object, the first of the surface mount coil component of the present invention,
A winding core whose winding axis is arranged perpendicular to the mounting surface, and upper and lower ridges formed integrally with the winding core at the upper and lower ends of the winding core, respectively, and the thickness of the upper ridge is 0.35 mm A drum type ferrite core (A) having a ratio of the outer diameter L2 of the upper collar to the core diameter L1 of 1.9 or more in terms of L2 / L1, and a lower edge of the drum type ferrite core. At least a pair of core-attached external electrodes (B) formed on the lower surface, and windings (C) wound around the core of the drum type ferrite core and having both ends electrically connected to the external electrodes And an inorganic filler-containing exterior resin (D) filled in a space between the upper and lower irons while covering a winding between the upper and lower irons of the drum-type ferrite core. In coil parts,
The inorganic filler-containing exterior resin (D) includes a thermosetting resin and an inorganic filler containing 20% by mass or more of a spherical filler with respect to 100 parts by mass of the inorganic filler-containing exterior resin (D), and contains an inorganic filler. Containing 70 to 90 parts by mass of the inorganic filler with respect to 100 parts by mass of the exterior resin (D);
It is characterized by that.

  According to the first surface mount coil component of the present invention, an inorganic filler-containing exterior resin (D) containing a thermosetting resin and an inorganic filler in a space between the upper and lower rims of the drum-type ferrite core. The strength of the product is improved, and even if a load is applied to the upper flange portion of the drum type ferrite core from the outside, damage to the upper flange portion can be prevented. And as an inorganic filler, what contains a spherical filler 20 mass% or more was used, and 70-90 mass parts of inorganic fillers were contained with respect to 100 mass parts of inorganic filler containing exterior resin (D). Since the fluidity at the time of filling with the filler-containing exterior resin (D) is not impaired, the productivity of the surface mount coil component is good. Furthermore, since the linear expansion coefficient between the inorganic filler-containing exterior resin (D) and the drum-type ferrite core (A) can be made closer, excellent durability can be obtained in the heat cycle test, and reliability against changes in the operating temperature environment Is expensive. Therefore, it is possible to obtain a surface mount coil component having a low profile and suitable for use in portable electronic devices such as a portable telephone and a digital still camera.

Further, the second of the surface mount coil component of the present invention includes a winding core whose winding axis is disposed perpendicular to the mounting surface, and an upper collar formed integrally with the winding core at each of upper and lower ends of the winding core, A drum type ferrite core comprising a lower collar, wherein the upper collar has a thickness of 0.35 mm or less and the ratio of the outer dimension L2 of the upper collar to the core diameter L1 is 1.9 or more in terms of L2 / L1 (A), at least a pair of core-attached external electrodes (B) formed on the lower surface of the lower arm of the drum-type ferrite core, and both ends of the core wound around the core of the drum-type ferrite core Covering the winding (C) electrically conductively connected to the external electrode and the winding between the upper and lower irons of the drum type ferrite core, the space between the upper and lower irons was filled A surface mount coil component having an inorganic filler-containing exterior resin (D). Te,
The inorganic filler-containing exterior resin (D) includes a thermosetting resin and an inorganic filler, and has a linear expansion coefficient of 5 to 20 ppm / ° C.
It is characterized by that.

  According to the second surface mount coil component of the present invention, an inorganic filler-containing exterior resin (D) containing a thermosetting resin and an inorganic filler in a space between the upper and lower rims of the drum-type ferrite core. The strength of the product is improved, and even if a load is applied to the upper flange portion of the drum type ferrite core from the outside, damage to the upper flange portion can be prevented. And by using what has a linear expansion coefficient of 5-20 ppm / degreeC as an inorganic filler containing exterior resin (D), the outstanding durability in a heat cycle test is obtained, and the reliability with respect to use temperature environment change is high. . Therefore, it is possible to obtain a surface mount coil component having a low profile and suitable for use in portable electronic devices such as a portable telephone and a digital still camera.

  In the first surface mount coil component of the present invention, it is preferable that at least a part of the spherical filler is a non-magnetic material.

  In the first and second surface mount coil components of the present invention, the glass transition temperature of the thermosetting resin is preferably 120 ° C. or higher. The coil component may be heated to about 100 ° C. during use, but if the glass transition temperature of the thermosetting resin is 120 ° C. or higher, the glass state can be maintained even during use, so that sufficient strength is obtained. And the occurrence of cracks can be further reduced.

  In the first and second surface-mounted coil components of the present invention, it is preferable that the inorganic filler contains ferrite. By including ferrite, the inductance value can be increased, and a surface mount coil component having desired inductor characteristics can be obtained.

  In the first and second surface mount coil components of the present invention, it is preferable that an average particle diameter D50 of the inorganic filler by a laser diffraction scattering method is 3 to 50 μm. According to this aspect, since the increase in the viscosity of the exterior resin (D) can be suppressed, the space between the upper and lower drums of the drum type ferrite core can be easily filled, and the surface mount coil component can be efficiently manufactured. Can do.

  According to the present invention, the space between the upper and lower shells of the drum-type ferrite core is filled with the inorganic filler-containing exterior resin (D) containing the thermosetting resin and the inorganic filler, so that the product strength Even if a load is applied to the upper flange portion of the drum type ferrite core from the outside, damage to the upper flange portion can be prevented. Moreover, since the linear expansion coefficient of this inorganic filler containing exterior resin (D) is close to the linear expansion coefficient of a drum type ferrite core (A), it has the outstanding durability in a heat cycle test, and with respect to a use temperature environment change. High reliability.

An embodiment of a surface mount coil component according to the present invention will be described with reference to the drawings.
1 is a perspective view seen from above showing the structure of the surface mount coil component of the present invention, FIG. 2 is a perspective view seen from below showing the structure of the surface mount coil component, FIG. It is a longitudinal cross-sectional view which shows the structure of the same surface mounting coil component.

  As shown in FIGS. 1 to 3, the surface mount coil component of the present invention is integrated with the core 11 in which the winding axis is arranged perpendicular to the substrate mounting surface and the core 11 at both upper and lower ends of the core 11. The drum type ferrite core 14 is composed of an upper rod 12 and a lower rod 13 formed in the above. The drum type ferrite core 14 has an upper collar 12 having a thickness d of 0.35 mm or less and an outer dimension L2 of the upper collar 12 with respect to the core diameter L1 (if the upper collar is circular, the diameter is a In this case, the ratio of the longer side in the vertical and horizontal directions) is L2 / L1, and the outer dimension is 1.9 or more. The requirement of the thickness d of the upper collar 12 is an indispensable requirement for reducing the height of the surface mount coil component, and the height dimension H can be made smaller (preferably, the height dimension H is 1.6 mm or less). The lower limit of the thickness d of the upper collar 12 is considered to change with the progress of the ferrite material processing technology and the sintering manufacturing technology, but should be as small as possible in terms of strength. If the ratio L2 / L1 of the outer diameter L2 of the upper collar with respect to the core diameter L1 is 1.9 or more, the maximum projecting dimension t in the radial direction from the outer circumference of the core 11 of the upper collar 12 (the outer circumference of the core) To the maximum outer diameter of the upper arm) can be made 1.0 mm or more, and the winding volume necessary for obtaining the choke characteristics can be ensured while suppressing the height dimension H.

A pair of external electrodes 15 a and 15 b directly attached to the core are formed on the lower surface of the lower flange 13 of the drum type ferrite core 14.
A winding 17 is wound around the core 11 of the drum type ferrite core 14 and both ends of the winding 17 are electrically connected to the external electrodes 15a and 15b by soldering or thermocompression bonding.
The space between the upper iron 12 and the lower iron 13 is filled with the inorganic filler-containing exterior resin 18 while covering the winding wire 17 between the upper iron 12 and the lower iron 13 of the drum type ferrite core 14. However, in the surface mount coil component of the present invention, the inorganic filler-containing exterior resin 18 is formed of a cured product of a resin composition containing a thermosetting resin and an inorganic filler.

  The thermosetting resin used for the inorganic filler-containing exterior resin 18 needs to have a glass state at room temperature when cured, and preferably has a glass transition temperature of 120 ° C. or higher, and 125 to 170 ° C. Is more preferable. Since the thermosetting resin in a glass state at normal temperature has high strength, even if external stress such as impact is applied to the upper collar 12 and the lower collar 13 of the drum type ferrite core 14, the upper collar 12 and the lower collar 13 are cracked. Hateful. In addition, the surface mount coil component may be heated to about 100 ° C. during use. However, if the glass transition temperature of the thermosetting resin is 120 ° C. or more, the glass state is maintained even in the temperature environment during use. Since it can be maintained, sufficient strength can be maintained.

  The type of thermosetting resin is not particularly limited, and examples thereof include polyamide resins, polyurethane resins, polycarbonate resins, polyethylene resins, polypropylene resins, urea resins, phenol resins, unsaturated polyester resins, polyimide resins, and melamine resins. . Among them, a resin that is liquid at normal temperature is preferable, and an epoxy resin is particularly preferable.

  The content of the thermosetting resin is preferably 10 to 30% by mass, more preferably 10 to 25% by mass, and more preferably 15 to 20% by mass. When the content of the thermosetting resin is within the above range, the product strength of the surface mount coil component can be improved.

  The inorganic filler used for the inorganic filler-containing exterior resin 18 is one that contains 20% by mass or more of spherical filler, preferably 40% by mass or more, more preferably 50% by mass or more. When the content of the inorganic filler is increased, the viscosity of the inorganic filler-containing exterior resin 18 before curing increases and fluidity at the time of filling is impaired, but an inorganic filler containing 20% by mass or more of a spherical filler should be used. Thus, an increase in viscosity can be suppressed even if the content of the inorganic filler is increased. The type of the spherical filler is not particularly limited, and examples thereof include spherical silica powder and spherical ferrite powder. It is preferable to use one containing at least a nonmagnetic spherical filler such as silica powder.

  The inorganic filler preferably contains ferrite. By including ferrite in the inorganic filler-containing exterior resin 18, the inductance value of the coil component can be increased, so that a surface-mounted coil component having desired inductor characteristics can be easily obtained. In addition, you may use a ferrite as a spherical filler.

  As for the average particle diameter of the inorganic filler, the average particle diameter D50 by laser diffraction scattering method is preferably 3 to 50 μm, and more preferably 5 to 25 μm. If the average particle diameter of the inorganic filler is within the above range, the viscosity of the resin composition before curing does not become too high and the fluidity is good. Since the space between them is easily filled with the inorganic filler-containing exterior resin 18, the productivity of the surface mount coil component can be improved.

  The inorganic filler is contained in an amount of 70 to 90 parts by mass, preferably 75 to 90 parts by mass, and more preferably 80 to 85 parts by mass with respect to 100 parts by mass of the inorganic filler-containing exterior resin. If the content of the inorganic filler is within the above range, the viscosity of the resin composition before curing does not become too high and the fluidity is good. It is easy to fill the space between them with the inorganic filler-containing exterior resin 18. Furthermore, the linear expansion coefficient of the cured product can be 5 to 20 ppm / ° C. (preferably 5 to 15 ppm / ° C.). Since the linear expansion coefficient of the drum type ferrite core 14 is about 5 to 20 ppm / ° C., the linear expansion coefficient of the inorganic filler-containing exterior resin 18 can be brought close to the linear expansion coefficient of the drum type ferrite core 14, and the heat cycle test Therefore, it is possible to obtain a surface mount coil component having excellent durability and high reliability against changes in the operating temperature environment.

  Thus, since the surface mount coil component of the present invention was formed by filling the resin composition containing the thermosetting resin and the inorganic filler as the inorganic filler-containing exterior resin 18, the product strength was improved, and the external Even if a load is applied to the upper flange 12 portion of the drum type ferrite core 14, the outer filler resin 18 containing the inorganic filler can be prevented from being deformed by external stress, and the upper flange 12 portion is not easily damaged. And as an inorganic filler, when what contains 20 mass% or more of spherical fillers and contains 70 to 90 parts by mass of the inorganic filler with respect to 100 parts by mass of the inorganic filler-containing exterior resin 8, the inorganic filler is contained. Since the linear expansion coefficient of the exterior resin 18 and the linear expansion coefficient of the drum type ferrite core 14 can be brought close to each other, excellent durability can be obtained in the heat cycle test, and the surface mounting coil has high reliability against changes in the operating temperature environment. Can be a part.

  The inorganic filler-containing exterior resin 18 is a cured product of a resin composition containing a thermosetting resin and an inorganic filler, and the cured product has a linear expansion coefficient of 5 to 20 ppm / ° C. (preferably 5 ppm). As long as it has a physical property of / ° C., it can be used without being limited to those described above. In order to adjust the linear expansion coefficient of the inorganic filler-containing exterior resin 18 to 5 to 20 ppm / ° C., there is a method of adjusting the type and blending amount of the thermosetting resin and the inorganic filler as appropriate.

  In this embodiment, the core 11 of the drum-type ferrite core 14 has a cylindrical shape, but is not limited to a cylindrical shape, and may be a substantially quadrangular prism shape. Moreover, the shape of the upper eyelid 12 and the lower eyelid 13 is not specifically limited, either, The shape of a disk or square or a rectangular plate shape of a rectangle may be sufficient. The external electrodes 15a and 15b may be arranged in at least one or two pairs on the lower surface 13a of the lower collar 13, and the position and shape thereof are not particularly limited.

  Next, an example of the manufacturing method of the surface mount coil component of this invention is demonstrated.

  First, a magnetic material powder mainly composed of Ni—Zn-based ferrite, an organic binder, and a solvent are mixed to prepare a slurry. The obtained slurry is granulated using a method such as a spray dryer and molded into a predetermined shape using a dry molding press. And the obtained molded object is baked and the drum type ferrite core 14 is obtained.

  Next, an electrode material paste containing a conductive metal such as Ag is applied to a region including the winding guide groove 19 on the lower surface 13a of the lower flange 13 of the drum type ferrite core 14 by a method such as screen printing, and is baked. External electrodes 15a and 15b directly attached to the core are formed. Then, Ni plating and tin plating, copper plating, or the like is applied to the baked electrode surface as necessary.

  Next, a winding 17 made of a copper wire or the like coated with an insulating resin such as polyurethane resin is wound around the outer periphery of the winding core 11 of the drum-type ferrite core 14, and both ends thereof are on the winding guide groove 19. Bend along the external electrodes 15a and 15b. Then, the solder paste containing flux component is stencil-printed on the surfaces of the external electrodes 15a and 15b so as to cover the ends of the winding 17 and dried, and then the solder paste is melted to peel the insulating resin of the winding 17 from the copper wire. At the same time, the copper wire ends of the windings 17 and the external electrodes 15a and 15b are soldered. Note that the soldering process can be divided before and after the winding of the winding, and the winding of the winding and the soldering can be performed as separate processes.

  Next, in the outer periphery of the winding 17 wound around the winding core 11 of the drum type ferrite core 14, in a space region sandwiched between the upper collar 12 and the lower collar 13 disposed opposite to the upper collar 12, A resin composition containing a thermosetting resin in a glass state at room temperature and an inorganic filler is filled using a dispenser, and the resin composition is cured to form the exterior resin 18. In this way, the intended surface mount coil component can be manufactured.

  The upper iron 12 and the lower iron 13 of the drum type ferrite core 14 (L1 = 1.3 mm, L2 = 2.5 mm, d = 0.34 mm, t = 1.85 mm, H = 0.86 mm) shown in FIG. The resin composition which becomes the precursor of the inorganic filler containing exterior resin 18 which consists of a composition shown in Table 1 in the space between them is filled with a dispenser and cured to produce surface mount coil components of Samples 1-9. did.

  In addition, as a thermosetting resin, the thing with a glass transition temperature of 120 degreeC mixed by the mass ratio of epoxy resin: curing agent = 80: 20 was used. As the spherical silica powder, one having an average particle diameter D50 of 8 μm by a laser diffraction scattering method was used. Further, as the non-spherical silica powder, one having an average particle diameter D50 by laser diffraction scattering method of 8 μm was used. As the non-spherical ferrite powder, one having an average particle diameter D50 by laser diffraction scattering method of 15 μm was used.

  The product strength and heat cycle performance of the obtained surface mount coil components were evaluated. Moreover, the coating workability | operativity and linear expansion coefficient of the resin composition used as the precursor of the inorganic filler containing exterior resin 18 were evaluated collectively. The results are shown in Table 2.

In addition, the product strength applied the load of 30N to the corner | angular part of the upper collar 12, and confirmed the presence or absence of the crack. A sample in which no crack was generated was rated as ◯, and a sample in which crack was observed was rated as x.
In addition, the heat cycle test was carried out by repeating the operations of holding at −40 ° C. for 30 minutes, holding at + 85 ° C. for 30 minutes, and cooling again to −40 ° C. for 100 cycles. confirmed. A sample in which no crack was generated was rated as ◯, and a sample in which crack was observed was rated as x.
Moreover, the coating workability of the resin composition is good when the fluidity is good and the coating workability is good, and the poor fluidity and the poor workability of the coating is x, and the coating workability is difficult. The thing was made into xx.

  From the above results, using a resin composition containing a thermosetting resin in a glass state at room temperature and an inorganic filler containing 20% by mass or more of spherical fillers, and the content of the inorganic filler is 70 to 90% by mass. The obtained surface-mounted coil components of Samples 1 to 3 were able to produce the surface-mounted coil components with high productivity, and further had high reliability with respect to changes in product strength and usage temperature environment.

It is the perspective view seen from the upper part which shows the structure of the surface mount coil components of this invention. It is the perspective view seen from the lower part which shows the structure of the same surface mounting coil component. It is a longitudinal cross-sectional view which shows the structure of the same surface mounting coil component.

Explanation of symbols

11: Winding core 12: Upper collar 13: Lower collar 14: Drum type ferrite cores 15a and 15b: External electrode 17: Winding 18: Exterior resin containing inorganic filler 19: Winding guide groove

Claims (6)

A winding core whose winding axis is arranged perpendicular to the mounting surface, and upper and lower ridges formed integrally with the winding core at the upper and lower ends of the winding core, respectively, and the thickness of the upper ridge is 0.35 mm A drum type ferrite core (A) having a ratio of the outer diameter L2 of the upper collar to the core diameter L1 of 1.9 or more in terms of L2 / L1, and a lower edge of the drum type ferrite core. At least a pair of core-attached external electrodes (B) formed on the lower surface, and windings (C) wound around the core of the drum type ferrite core and having both ends electrically connected to the external electrodes And an inorganic filler-containing exterior resin (D) filled in a space between the upper and lower irons while covering a winding between the upper and lower irons of the drum-type ferrite core. In coil parts,
The inorganic filler-containing exterior resin (D) includes a thermosetting resin and an inorganic filler containing 20% by mass or more of a spherical filler with respect to 100 parts by mass of the inorganic filler-containing exterior resin (D), and contains an inorganic filler. Containing 70 to 90 parts by mass of the inorganic filler with respect to 100 parts by mass of the exterior resin (D);
A surface mount coil component characterized by the above.   The surface mount coil component according to claim 1, wherein at least a part of the spherical filler is a non-magnetic material. A winding core whose winding axis is arranged perpendicular to the mounting surface, and upper and lower ridges formed integrally with the winding core at the upper and lower ends of the winding core, respectively, and the thickness of the upper ridge is 0.35 mm A drum type ferrite core (A) having a ratio of the outer diameter L2 of the upper collar to the core diameter L1 of 1.9 or more in terms of L2 / L1, and a lower edge of the drum type ferrite core. At least a pair of core-attached external electrodes (B) formed on the lower surface, and windings (C) wound around the core of the drum type ferrite core and having both ends electrically connected to the external electrodes And an inorganic filler-containing exterior resin (D) filled in a space between the upper and lower irons while covering a winding between the upper and lower irons of the drum-type ferrite core. In coil parts,
The inorganic filler-containing exterior resin (D) includes a thermosetting resin and an inorganic filler, and has a linear expansion coefficient of 5 to 20 ppm / ° C.
A surface mount coil component characterized by the above.   The surface mount coil component of any one of Claims 1-3 whose glass transition temperature of the said thermosetting resin is 120 degreeC or more.   The surface mount coil component according to any one of claims 1 to 4, wherein the inorganic filler contains ferrite.   The surface mount coil component of any one of Claims 1-5 whose average particle diameter D50 by the laser diffraction scattering method of the said inorganic filler is 3-50 micrometers.

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