JP2005158976A - Case core and inductor using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inductance device with a high inductance value by keeping a space formed by a ferrite case and a ferrite core as small as possible without damaging a winding. <P>SOLUTION: The case core 11 is provided with a housing part 12 to arrange a coil 14 that is formed by winding a winding 15 around a ferrite core 17. The housing part 12 is open, the whole body is cylindrical, and its bottom is blind. In addition, a pair of recessed parts 13 are formed on the facing side surfaces of the housing part 12. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a case core that houses a coil formed by winding a winding around a ferrite core, and also relates to a surface-mount inductor that is used in mobile communication devices such as a mobile phone and a simple mobile phone.

  As shown in FIGS. 7 (a) and 7 (b), the filter circuit of a cellular phone has a flange portion 27 formed at each end of the core portion 26 and a leg portion 28 continuous to each flange portion 27. A coil 14 formed by winding the winding 15 around the core portion 26 of the ferrite core 17 having the electrode 33 on each leg portion 28 is used as the inductor 30. Further, as shown in FIG. 7 (c), winding portions 27 are formed at both ends of the core portion 26, and wound around the core portion 26 of the ferrite core 17 having an electrode 33 on one of the flange portions 27. A coil 14 formed by winding a wire 15 is used as an inductor. And these inductors perform actions, such as impedance matching (refer patent document 1).

  However, an inductance value necessary for performing a noise removing action or the like of a power supply circuit or the like that has recently been increasing in demand has not been obtained with the structure shown in FIG. The main factor that the required inductance value cannot be obtained is that the magnetic flux 18 is in the air in the structure of the coil 14 shown in FIGS. 7A to 7C as shown in FIGS. This is because the magnetic flux 18 is easily attenuated.

  In order to keep the flow of the magnetic flux 18 satisfactorily, as shown in FIG. 9, a proposal has been made that the inductor 14 is formed by arranging the coil 14 in a cylindrical case core 34 having the accommodating portion 12 ( Patent Document 2).

  As shown in FIG. 9, the inductor 30 includes a flange portion 27 formed at each end of the winding core portion 26 and leg portions 28 continuous to the flange portions 27, and a ferrite core having electrodes 33 on each leg portion 28. The winding 15 is wound around the winding core portion 26 of the 17 and the end of the winding 15 is connected to the electrode 33 of the leg portion 28 to form the coil 14, and then the coil 14 and the cylindrical case core 34 are arranged on the side surface. It is formed by applying and fixing an epoxy resin (not shown).

The ferrite core 17 is made of a material mainly composed of ferrite, and the electrode 33 of each leg 28 is coated with a paste made of Ag or the like and baked, and then an Ni layer or the like is formed by electrolytic plating or the like. An Sn layer or SnPb layer is formed on the upper layer by electrolytic plating or the like. The coil 14 is produced by thermocompression bonding the terminal end of the winding 15 to the electrode 33 formed on the bottom surface of the leg portion 28 of the ferrite core 17.
JP 2002-170717 A JP 2000-182839 A

  However, in the inductor 30 using the cylindrical case core 34 as shown in FIG. 9A, the upper magnetic flux 18 still passes through the air as shown in FIG. Has not been completely eliminated, and there are cases where the inductance value necessary for noise removal of the power supply circuit cannot be obtained sufficiently.

  Further, as shown in FIG. 9B, the winding 15 protrudes from the outer periphery of the winding core portion 26 of the ferrite core 17, and the winding 15 may come into contact with the case core 34 to be broken. It was.

  In order to prevent this, it is necessary to provide an appropriate space 16 of about 0.15 mm between the inner dimension of the case core 34 and the ferrite core 17 of the coil 14 as shown in FIG. This is because a copper wire of about φ0.04 mm is normally used as the winding 15 wound around the winding core portion 26, and the interval between the winding 15 and the case core is kept around 0.10 mm. As shown in FIG. 9B, since the magnetic flux 18 must pass through the space 16, further attenuation of the magnetic flux 18 occurs, resulting in a decrease in inductance value.

  In order to solve the above problems, the case core of the present invention is a case core having a storage portion for placing a coil formed by winding a winding around a ferrite core, and the bottomed tube having the storage portion opened And having a pair of recesses facing the side surface of the storage portion.

  Moreover, it has the recessed part which follows the said recessed part in the bottom face of the said accommodating part, It is characterized by the above-mentioned.

  Moreover, the said accommodating part is a shape which has a corner | angular part, and has a notch part which protrudes toward the outer periphery of a case core in each corner | angular part.

  Furthermore, the inductor is formed by arranging a coil in the housing part of the case core described in any one of the above, and the winding part of the coil is arranged so as to correspond to the concave part.

  Furthermore, the coil winds a winding around a core portion of a ferrite core that includes a core portion, a flange portion formed at each end of the core portion, and a leg portion continuous to each flange portion. In addition, both ends of the winding are connected to the respective leg portions, and the end portions of the leg portions are arranged so as to protrude from the case core.

  According to the present invention, a pair of case cores having a storage portion for arranging a coil formed by winding a winding around a ferrite core has a bottomed cylindrical shape in which the storage portion is opened and faces the side surface of the storage portion. Thus, the space between the case core that attenuates the magnetic flux and the ferrite core of the coil can be kept to a minimum without damaging the winding.

  Furthermore, by having a concave portion that is continuous with the concave portion on the bottom surface of the storage portion, the space between the case core and the ferrite core of the coil that causes magnetic flux non-uniformity is minimized without damaging the winding. Is possible.

  Further, the storage portion has a shape having a corner portion, and a case core that attenuates the magnetic flux without causing damage to the ferrite core by having a cutout portion protruding toward the outer periphery of the case at each corner portion, and It is possible to minimize the space with the ferrite core.

  An inductor in which a coil is disposed in the housing part of the case core according to any one of the above, wherein an inductor that obtains a high inductance value by housing the winding part of the coil so as to correspond to the recess is manufactured. It becomes possible.

  In addition, the coil winds a winding around a core portion of a ferrite core including a core portion, a flange portion formed at each end of the core portion, and a leg portion continuous to each flange portion. The both ends of the winding are connected to the respective leg portions, and the end portions of the leg portions are arranged in the storage portion so as to protrude from the case core. As a result, it is possible to effectively prevent the magnetic flux from being attenuated by passing through the electrodes, and to easily check the solder frit after mounting on the circuit board.

  As shown in FIG. 1 (a), the present invention is a case core 11 having a storage portion 12 for arranging a coil, and the storage portion 12 of the case core 11 as shown in FIG. 1 (b). The inductor 30 is configured by housing the coil 14 formed by winding the winding 15 around the ferrite core 17.

  The ferrite core 17 forming the coil 14 includes a winding core portion 26, leg portions formed on both ends thereof, and electrodes 33 formed on the leg portions, and the terminal portion of the winding 15 is heated to the electrode 33. The coil 14 is formed by crimping and connecting, and the coil 14 is disposed in the housing portion 12 of the case core 11 and fixed to the case core 11 using an epoxy adhesive or the like.

Here, the case core 11 of the present invention is made of a ferrite material made of Fe ₂ O ₃ , NiO, ZnO or the like, has a bottomed cylindrical shape in which the storage portion 12 is opened, and is opposed to the side surface of the storage portion 12. It has the recessed part 13 of this.

  When the inductor 30 using the case core 11 is formed as shown in FIG. 1B, the recess 13 is formed so that the winding 15 of the coil 14 accommodated in the accommodating portion 12 of the case core 11 corresponds. As shown in the plan view of FIG. 2A, the space 16a can be kept appropriately narrower than the diameter of the winding 15 without contacting the winding 15 of the coil 14 and the case core 11. Therefore, it is possible to prevent a short circuit between the windings 15 when the coating of the windings 15 is peeled off or damaged. At the same time, the other space 16b between the case core 11 and the ferrite core 17 can be set very narrow, and the space 16b in the atmosphere that attenuates the flow of the magnetic flux 18 formed by the ferrite core 17 and the case core 11 is minimized. Since it can be limited to the limit, as shown in FIG. 2B, the flow of the magnetic flux 18 can be kept good, and a high inductance value can be obtained.

  The storage portion 12 has the same shape as the outer shape of the coil 14, and is set so that the spaces 16 a and 16 b are as small as possible without touching when the coil 14 is placed on the case core 11.

  Moreover, the recessed part 13 formed in the said case core 11 should just be provided so as to oppose the side surface of the accommodating part 12, as shown to Fig.1 (a), In this case, when arrange | positioning the coil 14 By applying an epoxy resin or the like to the bottom surface, it is possible to fix the coil 14 and at the same time protect the winding 15.

  Furthermore, it is preferable to form the said recessed part 13 continuously from a side surface to a bottom face, as shown to Fig.3 (a).

  This is to further minimize the space 16 of the ferrite core 17 of the coil 14 disposed in the bottom portion 19 of the case core 11 and the housing portion 12 of the case core 11 and to keep the flow of the magnetic flux 18 well.

  Also in this case, when the coil 14 is fixed, it is possible to protect the winding coating at the same time as fixing the coil 14 by inserting an epoxy-based adhesive at the bottom.

  Moreover, it is preferable that the inner peripheral surface 21 of the storage part 12 of the case core 11 and the connection part 22 of the recessed part 13 are connected by a smooth surface as shown in FIG. 3A, and the acute angle of the connection part 22 is the case. This is to prevent the core 11 from being a starting point of breakage, and to prevent the coating of the winding 15 from being peeled off and broken to cause a short circuit between the windings. When the radius of curvature R of the connecting portion 22 is less than 0.02 mm, stress concentration occurs in the connecting portion, which becomes a starting point for destruction, and the fracture strength of the case core is significantly reduced. For this reason, it is preferable that the connection part 22 is comprised by the curvature radius R 0.02 mm or more.

  Further, as shown in FIGS. 3B and 3C, the housing portion 12 of the case core 11 has a shape having a corner portion, and a notch portion that protrudes toward the outer periphery of the case core 11 at each corner portion. 24 is preferably formed.

  This is because the case core 11 and the ferrite core are arranged when the coil 14 is arranged when the inner dimension of the housing portion 12 of the case core 11 and the outer dimension of the ferrite core 17 are approximated in order to keep the flow of the magnetic flux 18 good. This is to prevent the contact 17 from being damaged.

  Further, it is preferable that the corner radius of the ferrite core 17 also has a radius of curvature R of 0.1 mm or less, and the width L of the notch 24 corresponding to this is an arc shape having a diameter of 0.5 mm or more or a length of 0.5 mm or more. The polygonal shape is preferred. Further, as shown in FIG. 3C, the cutouts 24 are preferably formed not only at the four corners of the side surface 25 of the storage unit 12 but also at the corners of the bottom surface 19 of the storage unit 12.

  Furthermore, it is desirable that the difference in the magnetic permeability of the material forming the case core 11 and the ferrite core 17 is within 300. This is because when the difference in magnetic permeability of each material exceeds 300, the frequency characteristics of the inductor such as the Q value are deteriorated. When the difference in magnetic permeability is within 300, it is possible to effectively prevent the deterioration of the frequency characteristic of the Q value while having a high inductance value.

  Here, the manufacturing method of the case core 11 and the inductor 20 of the present invention will be described.

The case core 11 and the ferrite core 17 are made of Ni—Zn based ferrite and Mn—Zn based ferrite, and are preferably made of Ni—Zn based ferrite from the viewpoint of frequency and surface resistance, for example, Ni—Zn ferrite. In this case, 47 to 51 mol% of Fe ₂ O ₃ , 10 to 14 mol% of NiO, 31 to 35 mol% of ZnO are essential components, 0 to 4 mol% of CuO, and other trace components are contained. A desired binder is added to and mixed with the raw material powder, and then filled into a mold and pressed to form a desired shape, and the obtained molded body is fired in the range of 900 to 1300 ° C. Here, it is important that the case core 11 has at least a pair of concave portions 13 that face the side surfaces 25 of the storage portion 12.

  After that, for the ferrite core 17, in order to produce the electrode 33 on the obtained sintered body, a thick film such as Ag or AgPd is printed and fired by using a method such as dipping, screen printing, or transfer. Bake. Then, several layers of Ni, Cu, Sn, Sn / Pb, Au, etc. are produced on the thick film according to the application and requirements by plating. In this plating process, a ferrite core 17 on which thick film printing has been performed is immersed in a plating solution in which a plating layer component is dissolved, and a current is applied to form a predetermined plating layer on the thick film of the ferrite core 17. It can be obtained by washing the plating layer adhering to the whole.

  The inductor 30 thus obtained is continuous with the winding core portion 26, the flange portion 27 formed at each end of the winding core portion 26, and each flange portion 27, as shown in FIG. 4A in particular. The winding 15 is wound around the winding core portion 26 of the ferrite core 17 composed of the leg portion 28, and both ends of the winding 15 are connected to the leg portions 28. It arrange | positions so that it may protrude from the case core 11.

  A high inductance value can be obtained by arranging the coil 14 so that the leg portion 28 protrudes from the housing portion 12 of the case core 11 as described above. Furthermore, by arranging the end portion so as to protrude from the case core 11, it is possible to prevent the magnetic flux 18 from passing through the electrode 33 and being attenuated as shown in FIG. The flow of 18 can be kept good, and a high inductance value can be obtained.

  Further, by projecting the leg portion 28 and disposing it on the case core 11 in this manner, it is confirmed whether the solder 32 is reliably wet with the inductor 30 after the inductor 30 is mounted on the circuit board 31 and the electric circuit is created. Can do. In this case, the projection dimension M is preferably 0.3 mm or more in order to facilitate image analysis or visual confirmation.

  Note that the case core 11 and the inductor 30 of the present invention are not limited to the above-described embodiment, and the space between the case core and the ferrite core is minimized even if the case core and the ferrite core have various shapes. What is necessary is just to have the recessed part kept to the limit, and if it is in the range which does not deviate from the summary of this invention, a various change is possible.

(Example 1)
Examples of the present invention will be described below.

First, a ferrite core 17 as shown in FIG. 5 (a) having the dimensions shown in Table 1 and a bottomed cylindrical shape as shown in FIG. The case core 11 having a pair of recesses 13 opposed to the side surfaces of the storage part 12, the case core 11 having the recesses 13 also on the bottom surface as shown in FIG. 5C, and the storage part as shown in FIG. A case core 11 having a notch at 12 was created. The dimensions A to L are values as shown in Table 1.

  An Ag layer was formed on the leg portion 28 of the ferrite core 17 by coating and baking, and an Ni layer and an Sn layer were formed thereon by electrolytic plating. A coil wire 14 was obtained by winding a φ0.05 mm urethane-coated copper wire as the winding 15 around the winding core portion 26 of the obtained ferrite core 17 26 times and crimping both ends of the copper wire to the electrode 33.

  And this coil 14 was fixed to the accommodating part 12 by apply | coating an epoxy resin to the bottom face of the case core 11 of FIG.5 (b). Similarly, the coil 14 was fixed to the storage portion 12 by applying an epoxy resin to the bottom surface of the case core 11 in FIG.

  Similarly, the coil 14 was fixed by applying an epoxy resin to the bottom surface of the case core 11 in FIG.

  As a comparative example, as shown in FIG. 5 (e), an epoxy resin is applied to the side surface of a cylindrical case core 34 having the same dimensions as FIGS. 5 (b) to 5 (d) and having no recess 13. And fixed.

  For the inductors shown in FIGS. 5A to 5D, as shown in FIG. 6A, the distance N of the space 16 between the ferrite core 17 of the coil 14 and the side surface of the case core 11 in each inductor is 0.05 mm. Become. When the case core 34 of FIG. 5 (e) as a comparative example is used, the distance N ′ of the space 16 is 0.25 mm as shown in FIG. 6 (b).

  And the inductance value of each obtained inductor sample was measured using the impedance analyzer.

The result is shown in 2.

  As is clear from the results in Table 2, when the case core 11 sample having a pair of recesses 13 opposed to the side surface of the storage portion 12 in the shape of a bottomed cylinder shown in FIG. .32 μH. Further, as shown in FIG. 5 (c), when the case core 11 sample having the recess 13 on the bottom surface is used, the inductance value is further improved to 10.00 μH, and it is stored as shown in FIG. 5 (d). When the case core 11 sample having the notch portion 24 in the portion 12 was used, the inductance value was 9.78 μH.

  On the other hand, it was found that the inductance value when the cylindrical case core 34 sample as a comparative example was used was as low as 6.90 μH.

  As a result, it was found that the space in the atmosphere that attenuates the flow of magnetic flux formed by the coil and the case core can be kept to a minimum, so that the inductance can be increased.

  The present invention relates to a case core for storing a coil formed by winding a winding around a ferrite core, and also relates to an inductor used in a mobile communication device such as a mobile phone or a simple mobile phone, and the coating of the winding is An inductor that can obtain a high inductance without being short-circuited between windings due to peeling or damage.

(A) is a perspective view which shows one Embodiment of the case core of this invention, (b) is a perspective view which shows the inductor using the case core of the figure (a). (A) is a top view which shows the inductor which used the case core of this invention, (b) is a top view which shows the mode of the magnetic flux of the inductor of the same figure (a). (A) is sectional drawing in the XX line of the inductor shown in FIG.1 (b), (b) is a top view which shows other embodiment of the inductor using the case core of this invention, (c ) Is a cross-sectional view of FIG. (A) is the perspective view which mounted the inductor using the case core of this invention on the circuit board, (b) is sectional drawing which shows the mode of the magnetic flux of the inductor of the figure (a). (A) is a perspective view which shows the coil used for the inductor in the Example of this invention, (b)-(d) is a perspective view which shows the case core in the Example of this invention, (e) is a comparative example. It is a perspective view which shows the case core in. (A) is a top view for demonstrating the space of the inductor shown to FIG.5 (b)-(d), (b) is a top view for demonstrating the space of the inductor shown in FIG.5 (e). is there. (A)-(c) is a perspective view which shows a various coil. (A)-(c) is sectional drawing which shows the flow of the magnetic flux of the coil of Fig.7 (a)-(c). (A) is sectional drawing which shows the flow of the conventional inductor and its magnetic flux, (b) is a top view of the figure (a).

Explanation of symbols

11: Case core 12: Storage part 13: Concave part 14: Coil 15: Winding 16: Space 17: Ferrite core 18: Magnetic flux 19: Bottom part 20: Concave part 21: Inner peripheral surface 22: Connection part 23: Corner part 24: Notch Part 25: Side face 26: Core part 27: Gutter part 28: Leg part 30: Inductor 31: Circuit board 32: Solder frit 33: Electrode 34: Cylindrical case core

Claims (5)

A case core having a storage portion for arranging a coil formed by winding a winding around a ferrite core, wherein the storage portion has a bottomed cylindrical shape with an opening and a pair of recesses facing the side surface of the storage portion A case core characterized by comprising: The case core according to claim 1, further comprising a concave portion that is continuous with the concave portion on a bottom surface of the storage portion. The case core according to claim 1 or 2, wherein the storage portion has a shape having a corner portion, and each corner portion has a cutout portion protruding toward the outer periphery. It is an inductor which arrange | positions a coil in the accommodating part of the case core in any one of Claims 1-3, Comprising: The winding part in the said coil is arrange | positioned so as to correspond to the said recessed part, It is characterized by the above-mentioned. Inductor. The coil is configured to wind a winding around a core portion of a ferrite core including a core portion, a flange portion formed at each end of the core portion, and a leg portion continuous to each flange portion, 5. The inductor according to claim 4, wherein both ends of the winding are connected to each leg portion, and the end portion of the leg portion is disposed so as to protrude from the case core.

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