JP2013084652A - Antenna coil component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna coil member compatible with surface mounting due to vacuum suction, which prevents damage to a magnetic core constituting the antenna coil member by protecting the magnetic core from external force and is less susceptible to disconnection of a coil due to winding thereof.SOLUTION: An antenna coil member includes a housing case, a magnetic core and a coil. The upper surface of the housing case is opened, and the magnetic core is fixed to the bottom thereof that can be seen from the opening. The magnetic core that appears in the opening is lower than a wall part of the housing case, thereby allowing the coil to be wound in a non-contact state with respect to the magnetic core in the housing case. A coating part made of insulating resin that forms a flat surface is disposed on the coil in the opening of the housing case.

Description

  The present invention relates to a coil component for an antenna used in a small wireless communication device such as a transponder, keyless entry, FM, or AM radio.

Various types of antenna coil components used in wireless communication devices have been proposed and put into practical use, such as those having an air-core coil structure and a coil support such as a core and a coil bobbin.
Such antenna coil components are required to improve electromagnetic characteristics while preventing an increase in size. FIG. 14 is a perspective view of a coil component for an antenna described in Patent Document 1, and a part thereof is shown as a fracture surface.

  This antenna coil component includes a coil assembly 101 in which a coil 112 is wound around a coil support 111 that functions as a magnetic core, a storage case 102 having a recess, and an end portion in the length direction of the coil support 111. And provided metal terminals 131 and 132. Both ends of the coil 112 are connected to the metal terminals 131 and 132. A part of the coil assembly 101 is accommodated in the opening side of the accommodation case 102, and the terminal portions 131 and 132 appear.

  With such a configuration, in particular, by using the coil support 111 as a magnetic core, the inductance of the coil component for antenna increases and the Q value also increases, so that the antenna characteristics can be improved. Further, the storage case 102 protects the coil 112 of the coil assembly 101 from being damaged during assembly and the like, and further, the storage case 102 can be vacuum-sucked, so that it is automatically mounted on a circuit board or the like. Is possible.

JP 2009-1111086 A

  The storage case 102 and the coil assembly 101 are fixed to almost the entire area of the inner surface of the storage case 102 with an adhesive. The coil support 111 includes a winding part 213 between the flange parts 211 and 212 located at both ends, and the connection surface with the storage case 102 is not flat, and the coil wound around the winding part 213 is not flat. The surface is also uneven. In the storage case 102 and the coil assembly 101, the connection surface is an uneven surface, and bubbles are likely to remain inside the adhesive. Furthermore, the storage case 102 has a structure in which it is difficult to discharge air trapped at the time of bonding in that it is configured in a cap shape.

  As a countermeasure, an adhesive inflow prevention portion (not shown) is provided, and when the storage case 102 is covered and fixed on the coil assembly 101, the entrained air is exhausted to the outside, and the inside of the adhesive 101 In the drying process of the adhesive, the thermosetting process, and the like, it is possible to avoid the problem that the bubbles are thermally expanded and the storage case 102 is deformed. However, it is not easy to discharge air entrained at a position away from the adhesive inflow prevention portion, and the problem of thermal expansion of bubbles remains. Providing a plurality of adhesive inflow prevention portions is not preferable because it complicates the structure of the storage case 102 and causes a decrease in strength due to a reduction in the bonding area.

  In addition, when the storage case 102 is put on the coil assembly 101 and bonded and fixed, the storage case 102 is lifted even if it is not deformed due to thermal expansion of bubbles, the flatness of the surface to be vacuum-sucked is impaired, and automatic mounting is possible. In some cases, it was not possible.

In the conventional structure, the metal terminals 131 and 132 for mounting on the circuit board are directly provided on the flange portions 211 and 212 at both ends of the coil support 111. The metal terminals 131 and 132 are complicated in shape, and it is difficult to join the coil support 111 while obtaining a predetermined connection strength, which requires a lot of man-hours.
Further, as the antenna coil component is made smaller, the coil support 111 is also made smaller and thinner. When the antenna coil component is directly mounted on the circuit board, the antenna coil part is easily affected by an external force caused by bending or bending generated on the circuit board. When the coil support 111 is made of a brittle material such as a ferrite core, it may be cracked or chipped to affect the magnetic characteristics.
In addition, such a structure in which the metal terminals 131 and 132 are directly provided on the coil support 111 has a problem of insulation in order to use a metal magnetic material for the coil support 111. In addition, when the shape is a magnetic core made of thin ribbons or a magnetic core made by solidifying powder with a binder such as glass or resin, it is stronger than ceramic materials such as ferrite cores. Is inferior, and a member for reinforcement is required separately.

  The coil 112 is directly wound around the coil support 111. The coil 112 is made of an insulation-coated electric wire such as polyurethane, polyamideimide, or enamel, and has a wire diameter of 30 μm to 200 μm. Therefore, the coating may be peeled off or disconnected at the corners of the coil support 111. It was.

  Therefore, in the present invention, the antenna coil member that can cope with surface mounting by vacuum suction, protects the magnetic core constituting the antenna coil member from external force, prevents the damage, and prevents the coil from being broken by winding. The purpose is to provide.

The present invention is a coil component for an antenna including a housing case, a magnetic core, and a coil,
The storage case includes a bottom portion, a wall portion rising from the bottom portion, an opening portion facing the bottom portion, and a flange portion having terminal electrodes at both ends in the length direction, and the bottom portion of the storage case. The magnetic core is fixed, the coil is wound between the flanges at both ends of the storage case, and both ends of the coil are fixed to the terminal electrodes, and appear on the opening side of the storage case. The magnetic core is lower than the wall, and the coil is wound in a non-contact state with the magnetic core,
An antenna coil component comprising a coating portion made of an insulating resin that forms a flat surface on the coil on the opening side of the housing case.

  In the present invention, it is preferable that a recess is provided at the bottom of the housing case, and the magnetic core is disposed and bonded to the recess. The concave portion functions as positioning for arranging the magnetic core.

  Moreover, it is preferable that the both ends of the storage case in the length direction open. The weight can be reduced by not providing walls at both ends in the length direction of the storage case. Further, since the terminal electrode is integrally formed on the collar portion, it is formed with a thickness larger than the wall portion of the trunk portion. For this reason, the resin constituting the housing case has a large volume change amount at the time of curing, and the housing case is likely to be distorted or deformed, but the influence can be reduced by opening both ends.

  In the present invention, it is preferable to use either a core made of a soft ferrite material or a core made of a magnetic metal magnetic material as the magnetic core.

  According to the present invention, since the coating portion provided on the coil has a flat surface, surface mounting by vacuum suction is easy without damaging the coil during suction, and the magnetic core is protected by the housing case. The damage is reduced, and the coil member for the antenna in which the coil is hardly broken can be provided by winding the coil around the housing case in a non-contact state with the magnetic core.

1 is an external perspective view of an antenna coil member according to an embodiment of the present invention. It is a top view of the coil member for antennas concerning one example of the present invention. It is a front view of the coil member for antennas concerning one example of the present invention. It is a bottom view of the coil member for antennas which concerns on one Example of this invention. It is a right view of the coil member for antennas which concerns on one Example of this invention. It is AA sectional drawing of the coil member for antennas which concerns on one Example of this invention. It is an external appearance perspective view of the storage case used for the coil member for antennas which concerns on one Example of this invention. It is a top view of the storage case used for the antenna coil member which concerns on one Example of this invention. It is a right view of the storage case used for the antenna coil member which concerns on one Example of this invention. It is AA sectional drawing of the storage case used for the coil member for antennas which concerns on one Example of this invention. It is an external appearance perspective view of the magnetic core (ferrite core) used for the coil member for antennas which concerns on one Example of this invention. It is an external appearance perspective view before the coating part formation of the coil member for antennas which concerns on one Example of this invention. It is a figure for demonstrating the formation method of a coating part. It is an external appearance perspective view of the conventional coil member for antennas.

Hereinafter, the configuration of the present invention will be described in detail with reference to the drawings.
FIG. 1 is an external perspective view of an antenna coil member according to an embodiment of the present invention. FIG. 2 is a plan view of an antenna coil member according to one embodiment of the present invention. FIG. 3 is a front view of an antenna coil member according to an embodiment of the present invention. FIG. 4 is a bottom view of the antenna coil member according to the embodiment of the present invention. FIG. 5 is a right side view of an antenna coil member according to an embodiment of the present invention. FIG. 6 is a cross-sectional view of the coil member for antenna according to an embodiment of the present invention, taken along line AA.

  The coil member 1 for an antenna of the present invention includes a housing case 3 made of an insulating resin, a magnetic core 5, and a coil 6. Terminal electrodes 4 are provided at both ends of the housing case 3, and the insulating resin is formed on the coil. A coating portion 7 is formed. In this embodiment, a ferrite core is used as the magnetic core 5.

FIG. 7 is an external perspective view of the storage case. FIG. 8 is a plan view of the storage case.
The housing case 3 used for the coil member for an antenna of the present invention includes a bottom portion 50, a wall portion 60 that constitutes two side surfaces that face the bottom portion 50 and face each other, and an opening portion 14 that faces the bottom portion 50. Walls are not formed at both ends in the length direction (hereinafter may be referred to as a direction) to form openings 17, and the openings 14 reach both ends in the length direction. In the present embodiment, the cross-section of the housing case 3 has an alphabetical U shape everywhere in a direction orthogonal to the length direction of the housing case 3 (hereinafter sometimes referred to as the b direction).

The housing case 3 includes a flange portion 13 having terminal electrodes 4 at both ends in the length direction, and the body portion 12 is defined between the flange portions 13. The region of the cross section in the b direction of the body part 12 is smaller than the flange part 13, and the step appearing between them depends on the diameter of the coil wound around the body part 12 and the thickness of the coding part 7. It is formed so as to be the same as or within the cross-sectional area.
The terminal electrode 4 is based on a thin metal material such as Cu or phosphor bronze having a thickness of about 0.05 mm to 0.2 mm and is plated to protect the metal material and improve solder wettability. In this embodiment, the cross-sectional shape extending from the upper surface of one wall portion of the flange 13 to the upper surface of the other wall portion through the side surface, the bottom surface, and the side surface is formed in an alphabetic C shape. It can take any shape and number, for example, it can be divided into two on the other side.
The terminal electrode 4 is integrally formed in the housing case 3 by a known method such as an insert molding method. Formation with an integral mold is easy and the connection strength with the housing case 3 is also high. It is also possible to fix the terminal electrode 4 to the housing case 3 with an adhesive or the like.
FIG. 9 is a side view of the resin case. A taper 32 is provided on the bottom side of the flange 13 so that the interval between the opposing walls 60 is narrowed so that the operation of housing the magnetic core is easy.

FIG. 10 is a cross-sectional view of the storage case taken along the line AA. The bottom portion 50 of the housing case 3 is formed to be lower by one step with a step across the body portion 12 and the flanges 13. An adhesive is applied to the recess 51 formed low, and the magnetic core 5 is inserted and fixed from the opening 14 side. The recess 51 functions as a positioning of the magnetic core 5 and helps to secure a space 30 with the coil 6 on the upper surface side. If used for positioning, a protrusion may be provided on the bottom or wall of the housing case 3 so as to be positioned at both ends of the magnetic core 5 instead of the recess 51.
Further, since the surface of the magnetic core 5 is flat, it is possible to reduce entrainment of bubbles during bonding, and it is possible to wet the surface even with a small amount of adhesive for fixing, so that a desired adhesive strength can be obtained. It can be fixed while being obtained. Furthermore, the stress due to the difference in linear expansion coefficient between the adhesive and the magnetic core 5 can be reduced, and the influence on the magnetic characteristics can be reduced. It is preferable to use an epoxy resin that is flexible and can absorb shocks.

  The resin material constituting the housing case 3 can be selected as appropriate. However, since the antenna coil component 1 is used for soldering such as reflow, the strength of the housing case 3 must be superior to the heat resistance. Since the antenna is used at a frequency in the kHz to GHz band, the dielectric characteristics are also important. For high frequency applications of MHz or higher, it is preferable to use heat resistant ABS resin, epoxy resin, glass epoxy resin, and acrylic resin.

FIG. 11 is an external perspective view of a magnetic core (ferrite core). Since the magnetic core 5 does not come into contact with the coil 6, it is not limited to Ni-based ferrite having a large specific resistance, such as Mn-based ferrite, iron-based or cobalt-based amorphous alloy, nanocrystalline alloy, iron aluminum silicon alloy, iron nickel alloy, etc. A metal magnetic material can be used. The shape is preferably thin and rod-like for easy mounting, but a plurality of small magnetic cores can be arranged in a long shape, and can take any shape and number.
If the magnetic core 5 is divided into a plurality of individual pieces, even if an external force such as bending acts on the housing case 3, the stress on the magnetic core 5 is dispersed, thereby reducing damage such as cracking and chipping. I can do it.

  When the end portion of the magnetic core 5 is located in the coil 6, the Q value may be reduced and the antenna performance may be reduced. The outer shape of the magnetic core 5 is naturally formed in a size that can be accommodated in the housing case 3, but the length of the magnetic core 5 is at least longer than the body 12 so that both ends of the magnetic core 5 appear from the end of the coil 6. preferable. In addition, since it may be displaced at the time of adhesion fixation with the storage case 3, and one end part may be located in the coil 6, the length of the magnetic core 5 is set also considering the dispersion | variation in a process.

FIG. 12 is a perspective view showing an external state in which a coil is wound around a housing case. The coil 6 was wound around the body portion 12 of the housing case 3 in which the magnetic core 5 was housed so as to be densely wound with a single layer. When the coil 6 is wound in a plurality of layers, the line capacitance is increased and the Q value is lowered. Therefore, the coil 6 is preferably wound in a single layer. Further, it is preferable that the coating portion for vacuum adsorption is tightly wound so that the resin does not leak from between the wires.
FIG. 4 is a bottom view of the antenna coil component. Both end portions 6a and 6b of the coil 6 are extended on the surface of the terminal electrode 4 on the bottom surface side of the housing case 3, and are joined by connection means such as welding, thermocompression bonding, or ultrasonic vibration. In thermocompression bonding, the ends 6 a and 6 b of the coil 6 are pressed with a heated head and diffusion bonded to the terminal electrode 4. In ultrasonic vibration, the end portions 6 a and 6 b of the coil 6 are pressure bonded to the terminal electrode 4 by vibration and heating of the head portion for bonding.
The connection position is not limited to the bottom surface, and can be appropriately selected as long as it is a planar shape of the terminal electrode 4 as necessary.

FIGS. 13A to 13E are diagrams for explaining a process of forming a coating portion on the coil.
As shown in FIG. 13A, an antenna coil component (hereinafter referred to as “uncoated component”) in which the coating portion is not formed is placed on the jig 22. The jig 22 is formed with a recess or protrusion for restricting the movement of the antenna coil component, which is omitted in the drawing. An appropriate temperature is provided by the dispenser 40 on the upper surface of the uncoated part (on the opening 13 side of the housing case 3) on the surface of the coil 6 tightly wound in the region of the body portion 12 including the central portion in the a direction of the housing case 3. The liquid coating member 7 ′ adjusted to be dropped. The liquid coating member may be applied by screen printing. The liquid coating member is excellent in solder heat resistance, has a low linear expansion coefficient, has excellent adhesive strength, and has a viscosity that does not easily cause liquid flow.

Next, as shown in FIG. 13 (b), the dropping of the liquid coating member 7 ′ moves the dispenser 40 in a certain direction from one end side to the other end side in the length direction of the uncoated part on the surface of the coil 6. Thus, the appropriate amount of the uniform liquid coating member 7 'is dropped.
As a result, the uncured liquid coating member 7 ′ is applied on the surface of the coil 6 as shown in FIG. At this time, the thickness of the liquid coating member 7 ′ protrudes slightly from the upper surface of the flange portion 13 of the housing case 3, and the distance h from the upper surface of the flange portion 13 to the upper surface of the liquid coating member 7 ′ is 0. 0.1 to 1 mm is preferable. If the distance h is less than 0.1 mm, flatness to the extent that vacuum suction is possible on the upper surface of the coating portion 7 after curing cannot be obtained. If the distance h is greater than 1 mm, the liquid coating member 7 ′ may wrap around the side surface of the coil 6 or spill out to the magnetic core 5 side, resulting in an appearance problem. Moreover, the coating part after hardening may protrude beyond the collar part 13 of the storage case 3, and may not satisfy the standard dimension of the coil component for antennas.
In addition, the flatness said here can be evaluated by the waviness measurement with a surface roughness meter, for example. For example, it is preferable that the surface undulation is 80 μm or less (both in the a direction and the b direction) when the measurement length is 3 mm and is measured at a site that is vacuum-sucked, such as the central part in the a direction of the housing case 3. If the measurable area is small and the measurement length cannot be obtained, the maximum measurable length is evaluated. The measurement length can be appropriately set depending on the nozzle diameter for vacuum suction.

As shown in FIG. 13 (d), a resin film 20 having a thickness of 80 μm to 300 μm is placed on the liquid coating member 7 ′ applied to the uncoated part, and further pressed with a flat plate 21 from above. The resin film 20 is easily separated from the liquid coating member 7 'after curing, and at least the surface in contact with the liquid coating member 7' is released by silicon coating so that good wettability can be obtained. It is preferred to use a treated PET film. Further, the flat plate 21 is preferably a resin member having a high flexibility, and more preferably a silicon rubber plate having a thickness of several millimeters.
In this state, the liquid coating member 7 ′ is cured under the standard curing conditions. The liquid coating member 7 ′ flows on the coil due to its fluidity and pressure. Even if air is entrained when the liquid coating member 7 ′ is dropped, the air discharge is not hindered except for the upper surface side on which the resin film 20 is disposed, so that the remaining bubbles in the coating portion 7 can be reduced. Further, even if bubbles remain, the antenna coil components are not damaged by thermal expansion.

  As shown in FIG. 13E, after the liquid coating member 7 'was cured, the flat plate 21 and the resin film 20 were removed. As a result, an antenna coil component was obtained in which a flat surface with a uniform (flat) upper surface of the coating portion 7 was formed.

  The antenna coil component according to the present invention will be specifically described below, but the configuration thereof is the same as that of the antenna coil component shown in FIGS. The present invention corresponds to a frequency of 88 MHz to 108 MHz.

The antenna coil component 1 includes a housing case 3, a magnetic core 5, a coil 6, and a coating portion 7 that forms a flat surface on the coil.
The housing case 3 formed by insert-molding the terminal electrode 4 made of phosphor bronze using glass epoxy resin has a total length of 10 mm, a length of the trunk portion 12 of 7 mm, and the terminal electrodes 4 of the flange portions 13 at both ends. The included width is 2 mm and the height is 1.3 mm. The upper surface is opened with a width of 1 mm and a depth of 0.7 mm. A concave portion 51 having a length of 8.5 m and a depth of 0.1 mm is further formed in the bottom portion 50 as viewed from the opening 14 side of the housing case 3. The terminal electrode 4 has Ni plating and Sn plating applied to the surface of phosphor bronze.

A sintered ferrite core as a magnetic core 5 is fixed to the recess 51 of the housing case 3. For fixing, an epoxy resin adhesive having excellent solder heat resistance was applied to the recess 51, and a sintered ferrite core was disposed thereon, and fixed by curing at 120 ° C. for 30 minutes.
The sintered ferrite core is mainly composed of ferric oxide (Fe ₂ O ₃ ), zinc oxide (ZnO), nickel oxide (NiO) and copper oxide (CuO), and bismuth oxide (Bi ₂ O ₃ ) as subcomponents. Silicon oxide (SiO ₂ ) is obtained by powder-molding and sintering calcined powder, and has an initial permeability μi of 10 (frequency 100 kHz).

  A coil 6 is obtained by winding 60 turns of an enameled wire having a wire diameter of 80 μm around the body 12 of the housing case 3 to which the sintered ferrite core is fixed, and both ends thereof are connected to the terminal electrode 4 on the lower surface side of the housing case 3. Thermocompression bonding was performed.

Further, a liquid coating member is dropped on the coil surface on the opening 14 side of the housing case 3, and the coating portion 7 is formed on almost the entire upper surface of the coil 6 by the procedure shown in FIGS. 13 (a) to 13 (e). Thus, the antenna coil component of the present invention was obtained. The thickness of the coating portion 7 is about 0.2 mm, and is substantially the same height as the flange portion 13 and the upper surface.
As the liquid coating member, a one-component thermosetting epoxy resin was used. Its characteristics are a linear expansion coefficient of 3.5 × 10 ⁻⁵ / ° C., a viscosity of 65 Pa · s, and a curing temperature of 100 ° C. The effect condition was 120 ° C. × 20 minutes.

  About the wave | undulation of the coating part 7 of the obtained coil component 1 for antennas, the evaluation number was evaluated as 100 pieces. The measurement length is 3 mm in the a direction and 1.5 mm in the b direction. Any sample waviness was 10 μm or less in two directions.

  Next, 1000 samples including 100 samples evaluated for swell were supplied to a chip mounter (automatic mounting machine) with embossed tape, and the suction nozzle of the automatic mounting machine was adsorbed by the coating part 7 formed on the flat surface, and the cream The solder was transferred and arranged on the circuit board coated with the mounting part. In mounting, there was no failure due to automatic adsorption by the chip mounter, and mounting on the circuit board was performed in an appropriate position range, and there was no problem such as mounting displacement.

  The circuit board on which the antenna coil component 1 was mounted was subjected to reflow soldering under a maximum temperature condition of 255 ° C. × 10 minutes. The appearance of the coil component for antenna after soldering was confirmed using a magnifying glass. However, no bubbles were generated in the coating portion 7, deformation of the housing case 3, cracking or chipping of the sintered ferrite core 5, and the coil 6. There was no occurrence of disconnection.

  Using 100 antenna coil components 1 mounted on a test board, the reception sensitivity was evaluated. Any antenna coil component 1 showed high reception sensitivity and good performance at a frequency of 88 MHz to 108 MHz.

DESCRIPTION OF SYMBOLS 1 Antenna coil component 3 Housing | casing case 4 Terminal electrode 5 Magnetic core 6 Coil 7 Coating part 12 trunk | drum 13 collar

Claims (4)

A coil component for an antenna including a housing case, a magnetic core, and a coil,
The storage case includes a bottom, a wall that rises from the bottom, an opening that faces the bottom, and a flange that includes terminal electrodes at both ends in the length direction.
The magnetic core is fixed to the bottom of the housing case;
The coil is wound between the flanges at both ends of the storage case, and both ends of the coil are fixed to the terminal electrodes.
The magnetic core that appears on the opening side of the housing case is lower than the wall, and the coil is wound in a non-contact state with the magnetic core,
An antenna coil component comprising: a coating portion made of an insulating resin that forms a flat surface on the coil on the opening side of the housing case.   The antenna coil component according to claim 1, wherein a concave portion is provided at a bottom portion of the housing case, and the magnetic core is disposed and bonded to the concave portion.   The antenna coil component according to claim 1 or 2, wherein both ends of the housing case in the length direction are opened.   4. The antenna coil component according to claim 1, wherein the magnetic core is one of a core made of a soft ferrite material and a core made of a magnetic metal magnetic material.

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