JP2005136009A - Ferrite core and common-mode noise filter using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the generation of the deterioration of the breakdown strength due to a short circuit by the contact of a conductor and an electrode and the contact of the conductor and a leg, when the conductor is wound on a ferrite core and the tip of the ferrite core is connected to the electrode formed on the base of the leg. <P>SOLUTION: The ferrite core is composed of a first collar 3 and a second collar 13, consisting of collars 1 formed at both ends of a core section 5 respectively, and a plurality of the leg sections 2 continued to each collar 1 and the electrodes 4 formed at ends on the base sides of each leg 2, and the cross sections of all legs 2 are kept fixed, in a direction toward the base sides from the core-section 5 side. In the ferrite core, a maximum length A, in parallel with the axial X direction of the core 5 in each leg 2 of the first collar section 3 is shortened by stages in a direction toward the legs 2 of the other side face from the leg sections 2 of one side face, while the maximum length A, in parallel with the axial X direction of the core section 5 in each leg 12 of the second collar section 13 is shortened in stages, in a direction toward the leg sections 12 of one side face from the leg sections 12 of the other side face. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a ferrite core suitable for common mode noise countermeasures for various electronic devices that handle high frequency signals, and a common mode noise filter used for a differential transmission circuit and the like.

  Conventionally, a common mode noise filter has been used as a countermeasure against unnecessary radiation of power supply lines and as a countermeasure against common mode noise of high frequency signals.

  As shown in FIG. 9, the common mode noise filter includes a flange portion 1 at both ends of the core portion 5 and a plurality of leg portions 2 continuous to the flange portion 1. The ferrite core 6 is obtained by forming the electrode 4 at the end of the wire, and a plurality of conducting wires 7 are wound around the core portion 5 of the ferrite core 6 by several turns to several tens of turns by bifilar winding or the like. The first tip and the end of winding are electrically connected to the electrode 4 on the bottom side of the leg 2 by soldering, thermocompression bonding, or the like.

  In such a common mode noise filter, when an in-phase current flows through the two conducting wires 7, the magnetic flux is added and the impedance is increased. Conversely, when a reverse phase current flows through the two conducting wires 7, the magnetic flux is canceled and impedance is hardly generated. As described above, the common mode noise filter is an electronic component having a filter function that the common-mode current hardly flows and the reverse-phase current easily flows.

  In the field of information communication equipment in which this common mode noise filter is used, there is a demand for miniaturization and weight reduction of parts. In accordance with the request, the size of the common mode noise filter is approximately 2025, which is an area of approximately square, which is an area at the time of mounting, is 3216 mm, 1.6 mm width, 3216, 2.5 mm length, 2.0 mm width. Similarly, 2012, 1608, and 1210 have been shifted to miniaturization.

  In Patent Document 1, as shown in FIG. 9, it is proposed to form a curved body at all ridge lines of each leg 2 in the ferrite core 6.

  By forming curved bodies having a radius of curvature of about 0.2 mm on all the ridge lines of the leg 2, it is possible to prevent problems such as short-circuiting of the conductor 7 due to the ridge and the deterioration of the withstand voltage. Further, by forming an inclined surface on the core part 5 side of the leg part 2, it is possible to connect the bifilar winding conductor 7 wound around the core part 5 to the electrode 4 at a more gentle angle. This has been shown to be a more reliable common mode noise filter.

  Next, in patent document 2, as shown in FIG. 10, forming an inclined surface in the leg part 2 is proposed.

  The conductor 7 is provided with an angle of less than 90 ° with respect to a vertical plane parallel to the direction of the axis X of the core 5 and an angle of over 90 ° with respect to the direction of the axis X of the core 5. It is said that a necessary interval can be provided between the electrodes 2 and the electrodes 4 of the leg portions 2 to be connected come into contact with the electrodes 4 of the adjacent leg portions 2 to reliably prevent a short circuit or a deterioration in breakdown voltage.

Further, when the conducting wire 7 is attached along the inclined surface, the bending angle of the conducting wire 7 can be performed at a gentle angle, and the breaking of the conducting wire 7 can be prevented, and a more reliable common mode noise filter and Has been shown to do.
JP 2002-329618 A Japanese Patent No. 3168972

  In the information and communication equipment field where common mode noise filters are used, there is a demand for smaller and lighter parts as equipment becomes smaller. Even in the case of wound common mode noise filters, the size of the square is 3 in the vertical direction. .2mm 1.6mm in size, 2.5mm in length 2.0mm in width, 2.0mm in length 1.2mm in width, 1.6mm in width 0.8mm in width, or 1.2mm in width 1.0mm in width It has shifted to miniaturization.

  Here, in the common mode noise filter using a ferrite core as shown in Patent Document 1, since the size of the leg portion 2 is reduced as the component size is reduced, the adhesion area at the time of mounting is reduced and the adhesion strength is reduced. It has a problem that it is difficult to obtain.

  Further, in a common mode noise filter using a ferrite core as shown in Patent Document 2, by providing the leg part 2 with an inclined surface, the area of the bottom surface of the leg part 2 is further reduced, and the adhesion strength during mounting is further weakened. Has the problem.

  The present invention solves the above-mentioned problems, and does not cause a short circuit due to the contact of the lead wire with the adjacent leg electrode, causes deterioration of the withstand voltage, or causes poor insulation, and also improves adhesion during mounting. An object of the present invention is to provide a ferrite core in which the area of the leg portion 2 is increased in order to raise and a common mode noise filter using the same.

  The ferrite core of the present invention includes a first core portion and a second flange portion including a core portion, a flange portion formed at each end of the core portion, and a plurality of leg portions continuous to each flange portion, A ferrite core having an electrode formed at an end portion on the bottom surface side of each leg portion, and a cross section of all the leg portions is constant from the core portion side toward the bottom surface side, The maximum length of the leg portion parallel to the axial direction of the core portion is gradually reduced from the leg portion on one side surface toward the leg portion on the other side surface, and the core in each leg portion of the second collar portion The maximum length parallel to the axial direction of the portion is gradually reduced from the leg portion on the other side surface toward the leg portion on the one side surface.

  Further, in the ferrite core of the present invention, the cross section of all the leg portions is constant from the core portion side to the bottom surface side, and the aspect ratio that is the ratio of the major axis to the minor axis on the bottom surface of the leg portion is larger than 1. And the bottom areas of all the leg portions are substantially equal, and the angle formed by the major axis of each leg portion of the first flange and the axis of the winding core portion is changed from the leg portion on one side surface to the leg portion on the other side surface. The angle formed by the major axis of each leg portion of the second flange portion and the axis of the winding core portion gradually decreases from the other side leg portion toward the one side leg portion. It is characterized by becoming.

  Furthermore, the ferrite core of the present invention includes a long axis formed on one side and a leg formed on the other side of the first and second flanges. The angle formed with the long axis is about 90 °.

  Still further, in the ferrite core of the present invention, the long axis of the leg portion formed on one side surface of the first flange portion and the second flange portion is perpendicular to the axis of the core portion. And the long axis of the leg part formed in the other side surface side is parallel to the axis | shaft of a core part, It is characterized by the above-mentioned.

  Furthermore, in the ferrite core of the present invention, the distance between the leg portions on at least both side surfaces of the leg portions formed on the first flange portion is equal to or larger than the width of the core portion, and The distance between the leg portions on at least both side surfaces of the leg portions formed on the second collar portion is equal to or larger than the width of the core portion.

  The ferrite core of the present invention is characterized in that the inner leg portion of the leg portions is smaller than the leg portions on both side surfaces.

  Furthermore, the common mode noise filter of the present invention is characterized in that a winding is wound around the ferrite core.

  According to the ferrite core of the present invention, the cross section of all the leg portions is constant from the core portion side toward the bottom surface side, and the maximum parallel to the axial direction of the core portion in each leg portion of the first flange portion. The length gradually decreases from the leg portion on one side surface toward the leg portion on the other side surface, and the maximum length parallel to the axial direction of the core portion in each leg portion of the second flange portion is on the other side surface. By shortening stepwise from the leg toward the leg on one side, a predetermined distance is created between the conductor and the electrode of the leg and the leg contact, causing a short circuit, or contact between the conductor and the leg. As a result, it is possible to prevent the occurrence of pressure breakdown deterioration, and the adhesive strength at the time of mounting is stabilized.

  Further, the cross section of all the leg portions is constant from the core portion side to the bottom surface side, the aspect ratio that is the ratio of the major axis to the minor axis on the bottom surface of the leg portion is greater than 1, and The bottom areas are substantially equal, and the angle formed by the major axis of each leg of the first flange and the axis of the winding core gradually decreases from the leg on one side to the leg on the other side. In addition, the angle formed between the long axis of each leg portion of the second flange portion and the axis of the winding core portion gradually decreases from the leg portion on the other side surface toward the leg portion on the one side surface. A predetermined interval is created between the lead wire and the leg electrode, which can cause a short circuit, or can prevent the occurrence of pressure deterioration caused by the contact between the lead wire and the leg portion. Stabilize.

  Furthermore, the angle formed by the long axis of the leg portion formed on one side surface and the long axis of the leg portion formed on the other side surface of each leg portion of the first and second flange portions is as follows. By setting the angle to about 90 °, a space can be provided between the conductor and the leg, and the electrode of the conductor and the leg contacts to cause a short circuit, or the breakdown voltage deterioration occurs due to the contact between the conductor and the leg. Can be prevented, and the adhesive strength during mounting is stabilized.

  Moreover, the long axis of the leg part formed on one side surface side of each leg part of the first collar part and the second collar part is formed perpendicular to the axis of the winding core part and on the other side surface side. The long axis of the leg part is parallel to the axis of the winding core part, so that a space can be provided between the conductor and the leg part. It is possible to prevent the deterioration of pressure resistance caused by the contact of the legs, and the adhesive strength during mounting is stabilized.

  Further, it is possible to eliminate a useless space in the arrangement of the leg portions, and to cope with downsizing.

  Furthermore, the distance between the leg parts on at least both side surfaces of the leg parts formed on the first collar part is equal to or larger than the width of the core part, and is formed on the second collar part. Since the distance between the legs on at least both sides of the leg is equal to or greater than the width of the core, a space can be provided between the conductor and the leg. Generation | occurrence | production of a pressure | voltage resistant deterioration which arises when an electrode contacts and produces a short circuit, or a conducting wire and a leg part contacts can be prevented.

  Furthermore, the inner leg of the leg can be made smaller than the legs on both sides, thereby providing a space between the conductor and the leg so that the electrode of the conductor and the leg are in contact with each other. Generation | occurrence | production of the pressure | voltage resistant deterioration which arises when a short circuit arises or a conducting wire and a leg part contact can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a state in which the bottom side of an embodiment of the ferrite core of the present invention is turned upward, and FIG. 1 (a) is a common mode noise filter formed by winding a conductive wire around the ferrite core of the present invention. FIG. 5B is a perspective view showing the ferrite core of the present invention.

  The ferrite porcelain constituting the ferrite core 6 is made of a magnetic material such as Ni—Zn ferrite, Mn—Zn ferrite, and the like. , A first collar part 3 comprising a plurality of leg parts 2a to 2c continuous to the collar part 1, and a second collar part comprising a collar part 11 and a plurality of leg parts 12a to 12c continuing to the collar part 11. 13 and an electrode 4 is formed at the bottom end of each leg 2a-2c, 12a-12c.

  For example, since the short side dimension B of the ferrite core 6 called 2520 size is 2.0 mm, the distance between the leg portions 2a to 2c and 12a to 12c formed on the first flange portion 3 and the second flange portion 13 is as follows. In consideration of the breaking strength and prevention of short circuit of the high-viscosity paste used for thick film printing, it is very small, about 0.4 mm.

  And as shown to Fig.1 (a), the conducting wire 7 is wound around the core part 5 of the ferrite core 6, and the both ends are connected to the electrode 4 of each leg part 2a-2c, 12a-12c, and common mode noise Configure the filter.

  Here, a first embodiment of the ferrite core of the present invention will be described.

  In the ferrite core 6 of the present invention, as shown in FIG. 1, the cross sections of the leg portions 2a to 2c and 12a to 12c are constant from the core portion 5 side to the bottom surface side, and without reducing the area of the bottom surface. It is important to form it, and from this, it is possible to eliminate the reduction of the adhesion area during mounting and to stabilize the adhesion strength.

  The cross sections of the leg portions 2a to 2c and 12a to 12c are cross sections in a plane parallel to the bottom surfaces of the leg portions 2a to 2c and 12a to 12c.

  In addition, the maximum lengths A1 to A3 parallel to the axis X direction of the core 5 in the respective leg portions 2a to 2c of the first flange portion 3 are stepped from the leg portion 2c on one side surface toward the leg portion 2a on the other side surface. And A1 <A2 <A3, and the maximum lengths A4 to A6 parallel to the axis X direction of the core portion 5 in the respective leg portions 12a to 12c of the second flange 13 are on the other side surface. It is important that the length is shortened stepwise from the leg 12a toward the leg 12c on one side, that is, A4> A5> A6.

  Thereby, when the conducting wire 7 is wound around the winding core portion 5 of the ferrite core 6 to form a common mode noise filter, when wiring from the conducting wire 7 of the winding core portion 5 to each of the legs 2a to 2c and 12a to 12c. A short circuit occurs between the conductor 7 and the legs 2a to 2c and 12a to 12c without any obstacles, and a predetermined distance is created between the conductor 7 and the electrodes 4 formed on the legs 2a to 2c and 12a to 12c. It is possible to prevent the occurrence of breakdown voltage degradation caused by contact between the conductor 7 and the legs 2a to 2c and 12a to 12c.

  Further, as shown in FIG. 2, when the first flange portion 3 and the second flange portion 13 each have two legs, the legs 2a, 2c, 12a and 12c have the same cross section as the core portion. The maximum lengths A1 and A3 parallel to the axis X direction of the core part 5 at the leg parts 2a and 2c of the first flange part 3 are constant from the side 5 to the bottom face side from the leg part 2c on one side surface. While gradually shortening toward the leg portion 2a on the other side surface, the maximum lengths A4 and A6 parallel to the axis X direction of the core portion 5 in the leg portions 12a and 12c of the second flange portion 13 are the other side surface. It is important that the length of the leg 12a gradually decreases from the leg 12a toward the leg 12c on one side.

  Accordingly, when a common mode noise filter is formed by winding the conductive wire 7 around the core portion 5 of the ferrite core 6, when wiring from the conductive wire 7 of the core portion 5 to each leg 2a, 2c, 12a, 12c. Prevents short circuit caused by contact between the conductor 7 and the electrodes 4 of the legs 2a, 2c, 12a, and 12c without any obstacles. In addition, it is possible to prevent the occurrence of breakdown voltage degradation caused by contact between the conductor 7 and the legs 2a, 2c, 12a, 12c.

  Further, by defining the maximum lengths A1 to A6 parallel to the axis X direction of the core part 5, the conducting wire 7 wound in the direction of the axis X of the core part 5 can be connected to the leg parts 2a to 2c, When wiring to 12a-12c, it goes to each leg part 2a-2c, 12a-12c radially from the point where the conducting wire 7 is distributed. That is, the radiation angle can be widened by changing the dimension parallel to the axial direction X of the core part 5 of each leg part 2a to 2c, 12a to 12c.

  Further, the maximum lengths A1 to A6 of the legs 2a to 2c and 12a to 12c are preferably set to 3/4 or less of A2 and A5 when A1 and A4 are 1, respectively. When A5 is 1, it is preferable to set A3 and A6 to 3/4 or less, and the conductor 7 is used when wiring from the conductor 7 of the core 5 to the legs 2a to 2c and 12a to 12c more reliably. A predetermined interval is created between the leg portions 2a to 2c and 12a to 12c, so that a short circuit caused by contact between the conductive wire 7 and the electrode 4 can be prevented, and deterioration of the breakdown voltage can be prevented. The same applies to the case where there are two leg portions 2 and 12 of the respective flange portions 3 and 13 as shown in FIG.

  Next, a second embodiment of the ferrite core of the present invention will be described with reference to FIGS.

  As shown in FIGS. 3A and 3B, the cross sections of all the leg portions 2a to 2c and 12a to 12c are constant from the core portion 5 side toward the bottom surface side, and the leg portions 2a to 2c and 12a are constant. When the aspect ratio, which is the ratio of the major axis C to the minor axis D on the bottom surface of -12c, is greater than 1 and the bottom areas of all the legs 2a-2c, 12a-12c are substantially equal, the first flange 3 The angle θ formed by the major axis C of each of the legs 2a to 2c and the axis X direction of the core 5 decreases gradually from the leg 2c on one side toward the leg 2a on the other side, The angle θ ′ formed by the long axis D of each leg portion 12a to 12c of the second flange portion 13 and the axis X of the winding core portion 5 is stepped from the other side leg portion 12a toward the one side leg portion 12c. It is characterized by becoming smaller.

  Thus, when it has a shape with an aspect ratio larger than 1, for example, elliptical or rectangular legs 2a-2c, 12a-12c as shown in FIGS. 3A and 3B, the legs 2a-2c. , 12a to 12c can be adjusted stepwise to adjust the amount of protrusion of the legs 2a to 2c and 12a to 12c toward the core 5 side, and the conductor 7 and the legs 2a to 2c and 12a to 12c can be adjusted. The distance can be designed freely.

  Moreover, the same effect as 1st Embodiment is acquired, and since the bottom area of each leg part 2a-2c and 12a-12c is a magnitude | size substantially equal, the adhesive strength at the time of mounting can further be stabilized. .

  In particular, since there are no corners in the case of an elliptical shape, there is an advantage that even if the lead wire 7 and the leg portions 2a to 2c and 12a to 12c come into contact with each other, it is difficult for pressure breakdown deterioration to occur.

  The long axis C is the longest axis that passes through the center of gravity of the bottom surfaces of the legs 2a to 2c and 12a to 12c and connects the outer circumferences, and the short axis D is the axis that passes through the center of gravity and is orthogonal to the long axis C. .

  Moreover, the fact that the bottom areas of the leg portions 2a to 2c and 12a to 12c are substantially equal indicates that the variation in the bottom area of each leg portion is within a range of ± 10%.

  Further, it is desirable that the angle θ formed between the legs 2a to 2c and 12a to 12c and the axis X is determined within a range in which a short circuit due to contact between the electrodes 4 does not occur after the electrodes 4 are formed between the adjacent legs. .

  Furthermore, it is desirable to make the design which minimizes the space | interval of the conducting wire 7 and leg part 2a-2c, 12a-12c regarding size reduction.

  Furthermore, in this case, as shown in FIG. 4, the leg portions 2 c and 12 c formed on one side surface side of the leg portions 2 a to 2 c and 12 a to 12 c of the first collar portion 3 and the second collar portion 13. It is preferable that the angle formed by the major axis C and the major axis C of the legs 2a, 12a formed on the other side surface is about 90 °.

  This includes a leg 2a formed on the other side, a leg 12c formed on the one side, and a leg 2c formed on the other side with the axis X, and a leg 12a formed on the one side. By rotating the wire inward, the space between the conductor 7 and the legs 2a to 2c, 12a to 12c can be increased, and the conductor 7 and the electrodes 4 of the legs 2a to 2c and 12a to 12c Further safety can be obtained by preventing occurrence of short circuit due to contact and deterioration of pressure resistance due to contact with the legs 2a to 2c and 12a to 12c.

  Further, as shown in FIG. 5, the long axis C of the leg portions 2 a and 12 c formed on one side surface of the leg portions 2 a and 2 c of the first collar portion 3 and the leg portions 12 a and 12 c of the second collar portion 13. It is more preferable that the long axis C of the leg portions 2c, 12a formed perpendicular to the axis X of the core portion 5 and on the other side face is parallel to the axis of the core portion 5.

  Accordingly, in addition to the same effect as described above, the dimension ratio between the dimension of the major axis C and the dimension of the minor axis D is further increased in the bottom surface shape of the legs 2a, 2c, 12a, and 12c. When the conducting wire 7 is wound as shown in FIG. 5), the gap between the conducting wire 7 and each leg 2a, 2c, 12a, 12c can be increased, and the safety is further improved.

  In FIG. 5, the leg portions 2 and 12 of the first collar portion 3 and the second collar portion 13 are two, respectively. However, in the case of three or more, it is similarly formed on one side surface side of the collar portions 3 and 13. The same effect can be obtained by specifying the angle between the formed leg part, the leg part formed on the other side surface, and the axis X of the core part 5.

  Next, a third embodiment of the ferrite core of the present invention will be described with reference to FIGS.

  As shown in FIGS. 6 (a), 6 (b), 7 (a), and 7 (b), a distance E between the leg portions 2a and 2c on both side surfaces formed on the first flange 3 is wound. The distance E ′ between the leg portions 12 a and 12 c on both side surfaces formed on the second flange 13 is the same as the width F of the core 5, which is the same as or larger than the width F of the core 5. Or larger than that.

  Accordingly, in the common mode noise filter in which the conducting wire 7 is wound as shown in FIGS. 6A and 7A, at least both the leg portions 2 a, 2 c, 12 a, and 12 c on the side surfaces are the core portion 5. A short circuit caused by contact between the conductor 7 and the leg electrode 4 is prevented without causing an obstacle when wiring from the conductor 7 wound around the leg 2a, 2c, 12a, 12c, and the conductor 7 and each leg. It is possible to prevent the deterioration of pressure resistance generated from the contact with the parts 2a to 2c and 12a to 12c.

  Further, as shown in FIG. 6, when the distance E at the boundary with the core part 5 is the same as the width F of the core part 5, the structure of the mold is greatly simplified, so that the mold manufacturing cost can be suppressed. it can.

  Furthermore, as shown in FIG. 7, when the distance E at the boundary with the core 5 is larger than the width F of the core 5, the distance E at the boundary with the core 5 is the width F of the core 5. Compared with the same case, the distance between the conductor 7 and the legs 2a, 2c, 12a, 12c is further widened, and the effect of preventing the deterioration of the breakdown voltage generated by the contact between the conductor 7 and the legs 2a, 2c, 12a, 12c is increased. .

  Furthermore, as a difference dimension setting when the distance E at the boundary with the core part 5 is larger than the width F of the core part 5, it is preferable to take at least the wire diameter of the conducting wire 7.

The distance E between the leg portions 2a and 2c is perpendicular to the axis X of the core portion 5 and indicates the distance at the boundary with the core portion 5, and is formed on the second flange portion 13. The distance E ′ between the side leg portions 12a and 12c is perpendicular to the axis X of the core portion 5, indicates the distance at the boundary with the core portion 5, and the leg portions 2 and 12 are tapered toward the bottom surface. The distance at the position continuous with the core part 5 is also shown in the case of Further, the width F of the core part 5 is the width of the center of the core part 5, but when the distances E and E ′ between the leg parts and the width F of the core part are the same as shown in FIG. Is the same as the position where the distances E and E ′ between the leg portions are taken as the width F of the core portion 5. Thus, each leg portion 2a, 2c, 12a, 12c and the core portion 5 The width E at the boundary between the legs 2a to 2c and 12a to 12c is wound around the core 5 even when the cross-sectional areas of the legs 2a to 2c and 12a to 12c become smaller toward the bottom surface, that is, in the case of a tapered shape. This is because the conductive wire 7 is not hindered.

  Further, in FIG. 6 and FIG. 7, the case has been described in which two each of the first collar part 3 and the second collar part 13 are provided, but the first collar part 3 and the second collar part 13 are each provided with legs. When three or more parts are provided, the distance E is the distance E at the boundary between the leg parts on both side surfaces and the core part 5.

  Moreover, as shown to Fig.8 (a), (b), when the 1st collar part 3 and the 2nd collar part 13 are each provided with three or more leg parts, each leg part 2a-2c, 12a-12c Among them, the inner leg portions 2b and 12b are smaller than the leg portions 2a, 2c, 12a and 12c on both side surfaces.

  As a result, in the common mode noise filter in which the conducting wire 7 is wound as shown in FIG. 8 (a), the leg portions 2a and 2c and the leg portions 12a and 12c on both side surfaces are made larger, so that adhesion at the time of mounting is performed. Since the area can be made large, the adhesion strength can be stabilized, and the inner legs 2b and 12b are smaller than the legs 2a, 2c, 12a and 12c on both side surfaces, so that the conductor 7 and the legs 2a to 2c. , 12a to 12c can be prevented from being deteriorated in pressure resistance.

  In addition, when the length of the legs 2a, 2c, 12a, and 12c in the axis X direction is 1, the length of the legs 2b and 12b in the axis X direction is preferably 3/4 or less. 7 and each leg part 2a-2c, 12a-12c can be prevented more reliably, and a pressure | voltage resistant deterioration can be prevented.

  In the first to third embodiments described above, the legs 2a to 2c and 12a to 12c have a constant cross section from the core part 5 side toward the bottom surface side. However, since the height of the legs 2 and 12 can be freely changed while using the same mold, the height of the legs 2 and 12 by changing the wire diameter of the conducting wire 7 can be changed. Adjustment can be performed easily.

  In addition, even if a request for further reduction in height occurs, it is possible to cope with it without changing the mold or modifying the mold, thereby reducing the mold cost.

  Next, the manufacturing method of the ferrite core 6 of this invention is demonstrated.

  For example, when producing a ferrite core 6 as shown in FIG. 1, first, a predetermined binder is added to a powder of Ni—Zn ferrite, Mn—Zn ferrite, or the like, which is a raw material for ferrite porcelain, and the powder is obtained by spray drying or the like. The raw material powder is obtained by granulating into granules suitable for molding.

  In particular, it is preferably made of Ni—Zn-based ferrite from the problem of operating frequency and surface resistance.

  Next, this raw material powder is filled in a die formed by dividing the core portion 5 and the leg portions 2a to 2c and 12a to 12c set in a powder press molding machine, and pressurized with a predetermined pressure to form a ferrite porcelain. A molded body is obtained.

  Thereafter, the obtained compact is fired and sintered at a predetermined firing temperature in a firing furnace such as an electric furnace or a gas furnace to obtain a sintered body that becomes a ferrite porcelain.

  Next, barrel processing is performed to perform surface treatment of the obtained sintered body and removal of burrs. The barrel processing is performed by, for example, putting a sintered body, water, an abrasive, etc. in a pot-shaped container made of porcelain and rotating it, so that batch processing is possible and processing costs can be reduced. . Also, when processing with a polishing agent as barrel processing, even when processing only with the frictional force between sintered bodies only with water, the polishing process is performed in water, so there is no surface roughness more than necessary, It has the feature that strength can be maintained even after barrel processing.

  The surface roughness of the sintered body of the ferrite porcelain forming the electrodes 4 of the leg portions 2a to 2c and 12a to 12c is preferably Ra 0.2 to 0.6 μm. When the surface roughness is less than Ra 0.2 μm, the thick films printed on the leg portions 2a to 2c and 12a to 12c are easily peeled off, and the adhesion strength when mounted as a product is lowered. On the other hand, when Ra is larger than 0.6 μm, the surface becomes rough and the strength decreases.

  The method for measuring the surface roughness is that the ferrite porcelain is fixed on a flat plate with the leg portions 2a to 2c and 12a to 12c side up, and the bottom portions of the leg portions 2a to 2c and 12a to 12c on which thick films are printed. It is measured by applying the stylus of the surface roughness meter. The Ra is adjusted by the number of rotations of a pot made of porcelain or the like during barrel processing. When the pot rotates quickly, Ra becomes large because the sintered bodies and the sintered body and the abrasive strongly collide with each other. If the number of revolutions of the pot is lowered, Ra becomes small because the collision between the sintered bodies and between the sintered body and the abrasive becomes weak.

  Thereafter, the electrodes 4 are formed on the bottom surfaces of the legs 2a to 2c and 12a to 12c. As this method, a thick film such as Ag or AgPd is printed using a method such as dipping, screen printing, or transfer, and then fired. Next, Ni, Cu, Sn, SnPb, Au, or the like is deposited on the thick film. Several layers are produced by plating according to the application and requirements. In this plating process, a predetermined plating layer is formed on the thick film formed on the ferrite porcelain by flowing a current by immersing it in a plating solution in which the components of the layer on which thick film printing is to be performed are dissolved, At this time, the ferrite core 6 formed by washing the plating solution adhering to the ferrite porcelain can be obtained.

  The ferrite core 6 thus obtained is suitably used as a common mode noise filter.

  A plurality of conducting wires 7 are wound around the core 5 of the ferrite core 6 in each of the above-described embodiments by bifilar winding or the like by several turns to several tens of turns. Each electrode 4 on the bottom side of the leg portion is electrically connected by soldering or thermocompression bonding.

  In this way, by changing the size, orientation, and shape of each leg, the distance between the adjacent leg and the electrode 4 can be maintained, and the insulation resistance between the electrodes 4 of the common mode noise filter can be maintained. Moreover, even if the conductive wire thickly attached to the adjacent electrode 4 passes by the electrode 4 of another leg part, it does not contact the leg part, so that a short circuit, a short circuit, and a pressure deterioration can be prevented.

(Example 1)
First, in order to obtain the ferrite core 6 of the present invention as shown in FIG. 2, a Ni—Zn ferrite material and a binder were kneaded as a magnetic material, and then a raw material powder was prepared with a spray dryer. Next, using this raw material powder, a mold formed by dividing the core 5 and the legs 2a to 2c and 12a to 12c was manufactured, set in a powder press molding machine, filled with the raw material and molded.

  Then, 20 sintered bodies that were fired at 900 to 1300 ° C. and became ferrite porcelain having four legs 2a, 2c, 12a, and 12c were produced.

  At that time, the maximum length of each leg 2a, 2c, 12a, 12c was set as follows.

Maximum length A1 of leg 2c, 12a ... 0.4mm
Maximum length A1 of legs 2a, 12c ... 0.3mm
And this sintered compact was put into the barrel apparatus which has the pot-shaped container which consists of porcelain, and the barrel process was given, and the ferrite ceramic which performed the surface treatment and the burr | flash removal was produced.

  Next, electrodes 4 were formed on all ferrite porcelains to obtain 20 ferrite core samples. The electrode 4 is formed by printing a thick film of Ag on the legs 2a, 2c, 12a, and 12c of the ferrite porcelain by baking, baking the thick film on the ferrite porcelain, and applying Ni and Sn on the thick film. Prepared by plating.

  The thickness of each electrode 4 is 20 μm for Ag, 2 μm for Ni, and 7 μm for Sn, and the dimension from the bottom surface side of the leg portions 2a, 2c, 12a, 12c of the Ag thick film toward the core portion 5 is 0.1 mm. It was.

  Subsequently, each obtained ferrite core sample is evaluated by the following method.

(1) Prepare 20 pieces of each ferrite core sample, and then wind the conducting wire 7 having a diameter of 0.1 mm for 7 turns and join it to each leg portion 2a, 2c, 12a, 12c by soldering. It was confirmed with a binocular microscope whether the parts 2a, 2c, 12a, and 12c were not in contact with each other.

(2) Legs 2a-12c and 2c-12a which are paired with HOZAN high resistance meter DT-110 are the other leg parts, each of the 20 ferrite core samples confirmed in evaluation (1). The continuity was checked for short circuit.

  As a method, it is confirmed whether or not the leg portion 12a is electrically connected to the leg portion 2a.

(3) Each ferrite core sample is soldered onto the mounting board using the electrodes 4 on the bottom surfaces of the legs 2a, 2c, 12a, and 12c, and the mounting board on which the ferrite core sample is mounted is mounted on a test stand made by AIKOH. Of the substantially square size when the ferrite core 6 is mounted using a CPU GAGE manufactured by AIKOH and fixed with a tape, the core portion 5 having a side of 2.0 mm in length is 5 mm / indented in a direction parallel to the mounting substrate. Pressurize at a rate of minutes. When the pressure was applied in this way, the strength when the legs 2a, 2c, 12a and 12c were all destroyed and the ferrite core sample was detached from the mounting substrate was evaluated.

The results are shown in Table 1.

  As can be seen from Table 1, there was no contact between the conductor 7 and each leg 2a, 2c, 12a, 12c.

  In addition, no problem occurs with respect to a short circuit caused by contact between the conductive wire 7 and the electrode 4.

  As for the last adhesion strength, the adhesion strength was almost the same as that of the conventional product.

  From the above, it has been proved that problems such as short circuit and deterioration of breakdown voltage can be solved by changing the maximum length of the legs 2a, 2c, 12a, 12c as shown in FIG.

(Example 2)
Next, in order to obtain the ferrite core 6 of the present invention as shown in FIG. 5 as in Example 1, a Ni—Zn ferrite material and a binder were kneaded as a magnetic material, and then a raw material powder was prepared with a spray dryer. Next, the raw material powder was used to manufacture and use a mold formed by dividing the core portion 5 and the leg portions 2a to 2c and 12a to 12c into a powder press molding machine, and then the raw material was filled and molded.

  Then, 20 sintered bodies that were fired at 900 to 1300 ° C. and became ferrite porcelain having four legs 2a, 2c, 12a, and 12c were produced.

  At that time, all the long axes C of the leg portions 2a, 2c, 12a, and 12c were set to 0.4 mm.

  And this sintered compact was put into the barrel apparatus which has the pot-shaped container which consists of porcelain, and the barrel process was given, and the ferrite ceramic which performed the surface treatment and the burr | flash removal was produced.

  Next, electrodes 4 were formed on all ferrite porcelains to obtain 20 ferrite core samples. The electrode 4 is formed by printing a thick film of Ag on the legs 2a, 2c, 12a, and 12c of the ferrite porcelain by baking, baking the thick film on the ferrite porcelain, and applying Ni and Sn on the thick film. Prepared by plating.

  The thickness of each electrode 4 is 20 μm for Ag, 2 μm for Ni, and 7 μm for Sn, and the dimension from the bottom surface side of the leg portions 2a, 2c, 12a, 12c of the Ag thick film toward the core portion 5 is 0.1 mm. It was.

  Next, the obtained ferrite core samples were comparatively evaluated in the same manner as in Example 1.

The results are shown in Table 2.

  As can be seen from Table 2, it is shown that there is no correspondence between the conductor 7 and the leg portions 2a, 2c, 12a, 12c, withstand pressure degradation.

  In addition, no problem occurs with respect to a short circuit caused by contact between the conductive wire 7 and the electrode 4.

  Regarding the final adhesion strength, the adhesion strength of FIG. 5 was 13.0 N compared to 9.1 N of FIG.

  From the above, it has been proved that changing the angles of the legs 2a, 2c, 12a, and 12c can solve the problems such as short circuit and deterioration of pressure resistance and increase the adhesion strength.

(A) is a perspective view which shows 1st Embodiment of the common mode noise filter of this invention, (b) is a perspective view which shows 1st Embodiment of a ferrite core. (A) is a perspective view which shows 2nd Embodiment of the common mode noise filter of this invention, (b) is a perspective view which shows 2nd Embodiment of a ferrite core. (A), (b) is a top view which shows the other example of 2nd Embodiment of the ferrite core of this invention. It is a top view which shows the other example of 2nd Embodiment of the common mode noise filter of this invention. (A) is a perspective view which shows the other example of 2nd Embodiment of the common mode noise filter of this invention, (b) is a perspective view which shows the other example of 2nd Embodiment of a ferrite core. . (A) is a perspective view which shows 3rd Embodiment of the common mode noise filter of this invention, (b) is a perspective view which shows 3rd Embodiment of a ferrite core. (A) is a perspective view which shows the other example of 3rd Embodiment of the common mode noise filter of this invention, (b) is a perspective view which shows the other example of 3rd Embodiment of a ferrite core. . (A) is a perspective view which shows the other example of 3rd Embodiment of the common mode noise filter of this invention, (b) is a perspective view which shows the other example of 3rd Embodiment of a ferrite core. . It is a figure which shows the conventional ferrite core. It is a figure which shows the conventional ferrite core.

Explanation of symbols

1: collar part 2: leg part 3: first collar part 4: electrode 5: winding core part 6: ferrite core 7: conductor 11: collar part 12: leg part 13: second collar part A1 to A6: maximum length B: Short side dimension C: Leg long axis D: Leg short axis E: Distance between leg portions on both side surfaces of the first buttock E ': Between legs on both side faces of the second buttock Distance F: winding core width X: winding core axis

Claims (7)

A first collar part and a second collar part each comprising a winding core part, a collar part formed at each end of the core part and a plurality of leg parts continuous to each collar part, and a bottom side of each leg part A ferrite core having an electrode formed at an end thereof, wherein the cross section of all the leg portions is constant from the core portion side toward the bottom surface side, and the core portion in each leg portion of the first flange portion The maximum length parallel to the axial direction of the second side portion gradually decreases from the leg portion on one side surface toward the leg portion on the other side surface, and parallel to the axial direction of the core portion in each leg portion of the second flange portion. A ferrite core characterized in that the maximum length is gradually reduced from the leg on the other side to the leg on the one side. A first collar part and a second collar part each comprising a winding core part, a collar part formed at each end of the core part and a plurality of leg parts continuous to each collar part, and a bottom side of each leg part A ferrite core having an electrode formed at an end, the cross section of all legs is constant from the core side toward the bottom side, and the ratio of the major axis to the minor axis on the bottom surface of the leg part A certain aspect ratio is greater than 1, and the bottom areas of all the leg portions are substantially equal, and the angle formed between the major axis of each leg portion of the first flange and the axis of the winding core portion is the leg portion on one side surface. The angle formed by the major axis of each leg of the second collar and the axis of the winding core is gradually reduced from the leg on the other side to the leg on the other side. Ferrite core characterized by decreasing in steps toward. An angle formed by the long axis of the leg formed on one side and the long axis of the leg formed on the other side of each of the first and second hooks is about 90. The ferrite core according to claim 2, wherein the ferrite core is °. Of the legs of the first and second collars, the leg formed on one side is perpendicular to the axis of the core and the other leg is formed on the other side. 4. The ferrite core according to claim 2, wherein the major axis of the portion is parallel to the axis of the core portion. 5. A first collar part and a second collar part each comprising a winding core part, a collar part formed at each end of the core part and a plurality of leg parts continuous to each collar part, and a bottom side of each leg part A ferrite core having an electrode formed at an end, wherein the distance between the leg portions on at least both side surfaces of the leg portions formed on the first flange portion is equal to the width of the core portion, A ferrite core characterized in that the distance between the leg portions on at least both side surfaces of the leg portions formed on the second flange portion is equal to or larger than the width of the winding core portion. The ferrite core according to claim 5, wherein an inner leg portion of the leg portions is smaller than a leg portion on both side surfaces. A common mode noise filter formed by winding a conducting wire around the ferrite core according to claim 1.

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